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AA61600-03C

Sepfember, 1973

Revision A
May, 1974

Revision B
March, 1975

Revision C
November, 1975

COMMUNICATIONS AND
INFORMATION (-IANDUNG

HARRIS CORPORATION Computer Systems Division

1200 Gateway Drive, Fort Lauderdale, Florida 33309 305/974-17OO

Revision C
November 1975

LIST OF EFFECTIVE PAGES

TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS: 377
CONSISTING OF THE FOLLOWING:

Page Page Page

No. Change No. Change No. Change

Title C 5-35 B 9-12 C

A thru B C 5-36, 5-36A C 9-13 Original

ithruxiii C 5-37 B 9-4 B

1-1,1-2 Original 5-38,5-39 A 9-5 C

1_3 C 5-40 thru 5-42 B 9-16 A

1-4 thru 1-^ Original 6-1 thru 6-2A C 9-17thru9-l9 Original

2-1 thru 2-5 Original 6-3,6-4 ^.. , ™ A

3_1 c 6-5 thru 6-8 Original 9-21 thru 9-24 B

3_2 B 6-9 thru 6-18 C 10-1 Original

3-3 thru 3-6 Original 6-18A. 1 thru Jn"?' L°in >; ^'' \

3-7 thru 3-9 C 6-18A.7 C 0-4 thru 10^ Or.g.na

4.1 thru 4-2A C 6-19 thru 6-22 Original 1- 9l'^'^t

4-3 Original 6-23,6-24 B M' I^-a Original

4_4 4.4A A 6-25 A 12-3 thru 12-4A C

4.5' C 6-26,6-26A C 12-5,12^ Original

4-6,4-7 Original 6-27 thru 6-32 Original 12-7 ^.. ,

4^8 B 6-33 B 12-8, 12-9 Original

4_9 Original 6-34 thru 6-40 Original 12-10 thru 12-13 A

4-10 C 6-41 A 12-14 B

4-nthru4-13 Original 6-42,6-43 B 12-15 A

4_14 B 6-44 A 12-16 Original

4-15 thru 4-18 C 6-45 Original 12-17 OrJnJno!

4 18A 4-19 C 6-46 B 13-1 thru 13-3 Original

4-20,4-21 Original 6-47 thru 6-49 Original 14-1,14-2 Original

4-22,4-23 C 6-50,6-51 A 4-3 B

4-24 B 6-52 C 15-1 ^. . ,

4 25 4-26 C 7-1 thru 7-i> Original 15-2 thru 15-9 Original

1.27 B 7-7 A 15-10,15-11 B

5-1 Original 7-8 thru 7-12 Original 15-llA. 1,A.2 C

5-2 thru 5-5 B ' 8-1 C 15-12 thru 5-27 Original

5_z Q 8-2 A 15-28 thru 15-29 A

5-6A 1 A 2 C 8-3,8-4 Original 15-30 thru 15-40 B

5-7 thru 5-8A C 8-5,8^ A A-1 C

5-9 Original 8-7 Original A-2 !, . . ,

5_10 A 8-8 C A-3 Original

5-lOA, 1 thru 9-1 Original A-4 B

5-10A.4 C 9-2, 9-2A B A -5, A -6 C

5_11 C 9-3 thru 9-6 Original A-7 B

5-12 thru 5-16 Original 9-7 A ^-8 Original

5-17 thru 5-22 A 9-8 C A-9A-10 C_

5-23 thru 5-26 Original 9-9 Original A-1 1 Original

5-27 thru 5-33 A 9-10, 9-lOA C A-12 C

5-34, 5-34A B 9-11 A A-13 Original
Insert Latest Revision Pages. Destroy Superseded Pages.

HARRIS CORPORATION Computer Systems Division

Revision C
November 1975

LIST OF EFFECTIVE PAGES

]

Page

Change

Page

Change

No.

A-14

A-15

Original

B-1, B-2

Original

B~3

C-1

Original

C-2

C-3

C-4, C-5

C-6 thru C-8

C-9, C-10

D-1

Original

D-2 D-3

D-4

Original

E-1

Original

IE -2 thru E-27

F-l

Original

F-2 thru F-7

G-1

Original

G-2 thru G-9

H-1

Original

H-2

Page Change

No. No.

Insert Latest Revision Pages. ^ Destroy Superceded Pages,

HARRIS CORPORATION Computer Systems Division

Revision C
November 1975

CONTENTS
SecHon Page

I GENERAL DESCRIPTION

1-1 Scope . 1-1

1-2 System Features 1-1

1-3 Foreground Operation .1-2

1-3. 1 Program Initiation 1-2

1-3.2 Execution Priorities f 1-2

1-3.3 Program Cataloging 1-2

1-3.4 Background Checkpointing 1-3

1-3.5 Program Communications 1-3

1-3.6 Program Restrict 1-3

14 Input/Output Facilities 1-4

]-5 File System Concepts 1-4

1-6 Batch Processing Capabilities 1-5

]"7 Accounting System 1-6

1-8 DMS Configurations 1-6

II DMS OPERATION

2-1 Scope 2-1

2-2 Programs 2-1

2-2. 1 Foreground Programs 2-1

2-2.2 Background Programs 2-3

2-3 Memory Allocation 2-4

2-4 Priority Structure and Program Interaction 2-5

2-4. 1 Context Switching 2-5

2-4.2 Timeslicing 2-7

III DISC AND FILE STRUCTURE

3-1 General 3-1

3-2 DMS Master Pack 3-1

3-3 Multiple Disc Units 3-2

3-4 Master Disc Directory 3-3

3-5 Disc Files 3-4

3-5. 1 Fi le Security 3-4

3-5.2 Passwords on Load Modules 3-5

3-5.3 File Types 3-5

3-5.4 File Accessing Methods , 3-8

IV SYSTEM SERVICES

4-1 General 4-1

4-2 Abort Service 4-2

4-2A Continguency Return 4-2

4-3 Input/Output Requests 4-2A

Revision C
November 1975

CONTENTS (CONT'D)

Page

Section

IV SYSTEM SERVICES (CONTINUED)

4-4 Exit Service ^"^

4-5 Termin Service ^"^

4-6 Hold Service ^"^

4-6A O/M Service JJ

4-7 Chain Service • • • -JZ

4-8 Info Service J~i

4-9 Sfunc Service • ^-^

4-10 Wait Service - J-°

4-1 1 Conv Service • ^"^

4-12 Special Foreground Services • Y

4-12. 1 Program Initiation 4- U

4-12.2 Foreground Interrupt Handling 4-0

4-12.3 Timer Scheduling ]" 2

4-12.4 System Common Accessing ^"4

4-12.5 Change Limits Service 4-4

4-13 Assign Service "J"^

4-14 Dynamic Core Manager (DCM) • 4- o

4-15 Find Pack Service 4- /

4-16 Untrcip Service • air

4-17 System Restricted Services 4- B

4-17. 1 File Creation 4- b

4-17.2 File Deletion • 4-9

4-17.3 Absolute Sector Read » 4-iy

4-17.4 Rename File 4-20

4-17. 5 Special Assign 4-/

4-17.6 Background Load Request 4-^

4-17.7 Write Absolute Sector 4-21

4-17.8 Search Master Disc Directory 4-22

4-17.9 Trigger lOEXEC 4-22

4-17. 10 Place File on Spool-In Queue •^-^^

4-17. 1 1 Place File on Spool-Out Queue 4-23

4-17. 12 Overlay Load 4-23

4-17, 13 Execute User Routine on Interval Timeout 4-/J

4_17, 14 Remove Execute Routine Entry 4-24

4-17. 15 Special Delete 4-25

4-17. 16 Special Absolute Sector Read 4-^0

4-17. 17 Special Absolute Sector Write 4-25

4-18 Executive Traps , /oa

4-18. 1 Power Fail/Power Restore 4-^6

4-18.2 Memory Protect/Instruction Trap 4-26

4-18.3 Stall Alarm 4-26

4-18.4 SAU Overflow/Underflow Trap 4-^6

4-18. 5 Address Trap 4-26

4-18.6 Interval Timer 4-^6

Revision C
November 1975

CONTENTS (CONT'D)

Section Pag^

V LOGICAL FILES AND PHYSICAL DEVICES

5-1 General 5-1

5-2 Input/Output FuncHons 5-1

5-2. 1 Common Device Function Codes 5-2

5-2. 2 Disc 5-4

5-2. 3 Magnetic Tape ^-7

5-2.4 Teletype Terminals 5-8

5-2. 4A TI Silent-700 Terminals with Cassettes 5-lOA. 1

5-2. 5 Paper Tape Reader 5-1 1

5-2.6 Paper Tape Punch 5-12

5-2.7 Card Reader 5-13

5-2. 8 Card Punch 5-14

5-2.9 Line Printer 5-15

5-2. 10 Real-Time Peripheral Equipment 5-17

5-2. 1 1 Alphanumeric CRTs 5-34

5-2. 12 Reader/Punch 5-37

5-2. 12. 1 Card Reader 5-37

5-2. 12.2 Card Punch 5-39

5-2. 13 Printer/Plotter . 5-40

5-2. 14 Incremental Plotter 5-41

VI BACKGROUND BATCH PROCESSING

6-1 Job Stream 6-1

6-1. 1 Special Assignment (Spooled Systems Only) 6-1

6-1.2 Reader "$" Cards 6-1

6-1.3 File Insertion Feature ....•" 6-1

6-2 Job Control Program 6-2

6-2. 1 SJob Statement 6-2

6-2.2 SEOJ Statement 6-3

6-2. 3 SAssign Statement 6-3

6-2.4 SDATE Statement 6-4

6-2. 5 SLINES Statement 6-5

6-2.6 SOPTIONS Statement 6-5

6-2.7 SFLAGS Statement 6-5

6-2.8 SINCLUDE Statement 6-5

6-2.9 SCATALOG Statement 6-6

6-2. 10 SCATGO Statement , . 6-6

6-2. 1 1 SLOADGO Statement .6-6

6-2. 12 SHOLD Statement 6-6

6-2. 13 STAPEOP Statement 6-6

6-2. 14 SADUMP Statement , . 6-7

6-2. 15 $OPEN Statement 6-7

6-2. 16 $CLOSE Statement .6-7

III

Revision C
November 1975

CONTENTS (CONT'D)

c *• Page
Section

VI BACKGROUND BATCH PROCESSING (CONT'D)

6-2c 17 SREW Statement ^"^

6-2. 18 $BSF Statement °~°

6-2 J9 $ ADF Statement °"°

6-2.20 SRPF Statement °"°

6-2„21 SSWEF Statement °-°

6-2.22 $XXYY Statement °"°

6-2.23 SEDITLF Statement °-°

6-2.24 $FILEMA Statement °-^

6-2„25 S NAME Statement . . . „ c . o . . o-^

6-2.26 $ Comments Statement. . . . „ „. o„. o ...... • O"'

6-3 File Manager o. ...o. co. o.. o ..= ...• o .. o .». o o "

6-3. 1 CREATE Statement „ . . . • » . o c . o . . o . . » . » J" ^

6-3,2 ESTABLISH Statement ^- '

6-3.3 DELETE Statement °-^

6-3.4 RENAME Statement • °-^

6-3„5 DMAP Statement °"^

6-3e6 DMAPS Statement J-^?

6-3.7 DUMP and DUMPBF Statement o- j

6-3. 8 SAVE Statement °"^

6-3.9 SAVEP Statement °"^

6-3. 10 SAVPAK Statement • °-^

6-3. 1 1 SAVUSR Statement °-^

6-3.12 LIST Statement • °-^

6-3.13 RESTORE Statement • °~\^

6-3. 14 RESPAK Statement » °'\°

6-3.15 RESUSR Statement °" °

6-3. 16 SAVMDD Statement °-\°

6-3. 1 7 REPSYS Statement . °-^

6-3J8 CLEAR Statement °- °

6-3. 19 ZEROPK Statement ^~ 5 a

6-3.20 READPK Statement ^" o a

6-3.21 FLAGPK Statement ^" qa o

6-3.22 ADVANCE Statement 5" o a o

6-3.23 REW Statement - z" qa o

6-3.24 WEF Statement z" qa o

6-3.25 ADF Statement « °- °A. 2

6-3.26 BSF Statement ^" qa'o

6-3.27 HOLD Statement a d a' ^

6-3.28 EXIT Statement I'Sat

6-3„29 SAV^RESTORE Formats ^'Ioa a

6-3.30 ERROR MESSAGES 6-18A.4

Revision C
November 1975

CONTENTS (CONT'D)

Section Page

VI BACKGROUND BATCH PROCESSING (CONT'D)

6-4 Link Caf-aloger 6-]i8A.

6-4. 1 Overlay Type Programs ,6-18A.

6-4.2 Link Cat-ologer Control Statements 6-22

6-4.3 Link Cataloging Process . .6-33

6-4.4 Link Cataloging Overlay Type Programs 6-34

6-4.5 Execution of Overlay Type Programs 6-34

6-4.6 Link Cataloger Output Format 6-36

6-4.7 Link Cataloging Background Programs Across the 32K

Boundary 6-36

6-4.8 Link Cataloger Table and Buffer Allocation 6-38

6-4.9 Common Memory Allocation .6-40

6-4. 10 Link Cataloging Program CHAIN Segments '.ik .6-40

6-4, 1 1 Link Catalog Map 6-41

6-4, 12 Code Processing 6-42

6-4. 13 Input and Code Placement 6-46

6-4. 14 Link Cataloger Error Message Codes 6-49

VII ACCOUNTING SUBSYSTEM

7-1 Scope 7-1

7-2 User Numbers 7-T

7-2, 1 Establishing User Numbers 7-1

7-2.2 Changing and Removing Users 7-1

7-2.3 Listing Users 7-1

7-2.4 Specifying User Numbers on Program Initiation 7-2

7-2.4.1 Programs Initiated via Operator

Communications 7-2:

7-2.4.2 Terminal Foreground Programs *7-2

7-2.4.3 Foreground Programs Initiated by other

Programs 7-2

7-2.4,4 Background Batch Programs 7-2

7-3 Terminal Operation 7.-3

7-4 Disc Files 7-3

7-5 Accounting Records 7-4

7-6 Accounting Files 7-4

7-6. 1 User Number File 7-5

7-6.2 User Name File 7-5

7-6.3 Accounting Record Files 7-7

Revision C
November 1975

CONTENTS (CONT'D)

Se ction

VII ACCOUNTING SUBSYSTEM (CON' D)

Page

7-7

7-7 Accounting Utility Program

7-7, 1 RUN Command iT'

7-7.2 Accounting Period Designation Statements /-o

7-7. 3 BLOCK Statement 7-8

7-7.4 SAVE Statement ir^

7-7. 5 DELETE Statement /"^

7-7.6 UTILIZATIONS Statement /-^

7-7. 7 Usage Summary Statements '-\

7-7.7. I USER Statement /-

7-7.7.2 USER/ACCOUNT Statement ........... 7-10

7-7.7.3 ACCOUNT Statement 7-10

7-7.8 ALPHA Statement 7-0

7-7.9 LIST Statement • • • {-\\

7-7. 10 TIMES Statement /-

7-7. 1 1 RATES Statement /- "

VIII TERMINAL OPERATION

8-1 Input Terminals - °",

8-1. 1 Theory of Operation • »-

8-2 Spooled Background Jobs °'"'

8-2. 1 $JOB Statement . • • o"'

8-2.2 Priority °-^

8-2.3 List Output Device o-^

8-2.4 Input File Size °-^

8-2. 5 Error Messages °"^

8-3 Acronim z~'i

8-4 Foreground Programs ^""^

8-5 Temiinal Priorities I'-i

8-5. 1 Default Priority o-;J

8-5.2 Priority Limit °-4

8-5.3 Fixed Priority °|2

8-6 Batch Input Terminal Operation °-^

8-6. 1 Non-Spooled Mode o-^

8-6. 2 Off-Line Mode 8-4

8-7 Teletype Tenninal Operation °~T

8-7. 1 Initiating Communications • °~^

8-7. 2 Line Cancel • °-^

8-7. 3 Program Abort ^"^

8-7.4 Terminating Communications o-^

8-8 Alphanumeric CRT Terminal Operations 8-5

Revision C
November 1975

CONTENTS (CONT'D)
Section Page

VIII TERMINAL OPERATION (CONT'D)

8-8. 1 InitlaHng CommunlcaHons 8-^5

8-8.2 Line Cancel and Line Editing 8-6

8-8. 3 Program Abort [ ^[ 8-6

8-8.4 Terminating Communications 8-6

IX OPERATOR COMMUNICATIONS

9-1 Operator Communications Facilities 9-1

9-1, 1 Program Control Commands 9-1

9-1.2 Foreground Interrupt Control 9-4

9-1.3 Program Assignment Commands 9-4

9-1.4 Spooling Control Commands 9-5

9-1.5 Accounting System Commands 9-6

9-1.6 System Status Commands 9-7

9-1.7 Time and Date Control Commands 9-8

9-1.8 Miscellaneous Commands , 9-8

9-2 Operator Messages 9-16

9-2, 1 Physical Device Errors 9-16

9-2.2 Manual ]/0 Requests !..'!! 9-17

9-2.3 Foreground Operational Error 9-18

9-2.4 User Program Operator Requests 9-18

9-3 Program Messages 9-39

9-4 DMS System Start--Up Procedure 9-21

X 1108 REMOTE JOB ENTRY SYSTEM

10-1 General Description 10-1

10-2 System Components 10-1

10-2. 1 Resident Device Handler *...*.'!!!.'!.'! 10-1

10-2.2 Foreground Communication Handler 10-1

10-2.3 Background Processor , IQ-I

10-3 Communications Control 10*2

10-3. 1 Establishing Communications 10-2

10-3.2 Terminating Communications 10-2

10-3. 3 Status ',.'.', 10-2

10-3.4 Special Functions 10-3

10-3. 5 Special Message from 1 108 !.*!!'*! JO-3

10-3.6 1 108 Down ] . 10-3

10-4 Transmitting a Job 10-3

10-4. 1 Initializing RJE '.'.'.'.'.'.'.'/.'.. 10-3

10-4.2 Background Job Stream 10-4

10-4.3 SREMOTE Card '..'..'.'.'. 10-4

10-4.3. 1 Class of Service 10-4

10-4.3.2 Listing Option , , [ 10-5

VI I

Revision C
November 1975

CONTENTS (CONT'D)

Section

Page

X 1 108 REMOTE JOB ENTRY SYSTEM ( CONT' D)

10-4.3.3 Size OpHon 10-5

10-4.4 Source Input '0-5

10-4. 5 Error Messages ^^"5

10-5 Remote Output 10-5

10-5. 1 Print Files JO-6

10-5.2 Punch Files 10-6

XI SYSTEM GENERATION

1 1 -1 Scope of Documentation 1 1 -1

11-2 General H-l

XII PHASE-I - SYSTEM CONFIGURATION

12-1 General 12-j

12-2 Parameterization 12-1

12-2. 1 Required Definitions 12-1

12-3 Peripheral Devices 12-1

12-3. 1 Terminals 12-2

12-3.2 Defining Peripheral Devices 12-3

12-3.3 Terminal Control Blocks 12-4

12-3.4 Maximum Number of Programs 12-6

12-3.5 Disc Storage Characteristics 12-6

12-3.6 Disc Storage Area Definition 12-6

12-3.7 Disc ]/0 Queue Size 12-10

12-3.8 Magnetic Tape Options 12-10

12-3.9 System Service Linkage 12-10

12-3. 10 Dynamic Cell Pool 12-10

12-3. 11 External Interrupt Definition Blocks 12-11

12-3. 12 Spooling Parameters 12-11

12-3. 13 Blocked ]/0 Parameters 12-1 1

12-3. 14 Background Default Options 12-1 1

12-3. 15 In-Core Directory Table 12-12

12-3. 16 Accounting Parameters 12-12

12-3. 17 Real-Time Peripherals 12-12

12-3. 18 Dispatcher Interrupt Definition 12-13

12-3. 19 VERSATEC Printer/Plotter , 12-14

12-4 Background Default File/Device Assignments. 12-15

12-5 Assembly Option Configuration 12-15

12-5. 1 SAU Option • 12-15

12-5.2 Bit Processor Option 12-15

12-5. 3 Machine Type 12-15

12-5.4 Spooleci/Interactive Option 12-15

12-5,5 Remote Job Entry Option 12-16

VMI

Revision C
November 1975

CONTENTS (CONT'D)

Section Page

XII PHASE-I - SYSTEM CONFIGURATION

12-5.6 Accounting OpHon 12-16

12-5.7 50 Cycle Power Option 12-17

12-6 Final Module Preparation 12-17

12-6. 1 System Linkage Module - SYSGEM 12-17

12-6.2 SYSDAT and BGDATA 12-17

12-6.3 DSR 12-17

XIII PHASE II - SYSTEM DEVELOPMENT

13-1 General 13-1

13-2 Phase II Procedures 13-1

13-2. 1 Bootstrap Module of Device Loader 13-1

13-2.2 SGS Absolute Load Module 13-1

13-2.3 SGS Disc Initialization Load Module 13^2

13-2.4 SGS Load Module of Resident DMS 13-2

13-2.5 Load Modules of Operator Communications Segments 13-3

13-2.6 Saving Master Disc Director Entries for Multiple Discs. . . . 13-3

13-2.7 Creation of Dynamic Disc Modules 13-3

13-2.8 Deletion of Temporary Files 13-3

XIV PHASE III - DISC INITIALIZATION

14-1 General 14-1

14-2 Procedures 14-1

14-2. 1 Loading SGS 14-1

14-2.2 Initial Job Control Statements 14-1

14-2.3 Disc Initialization 14-3

14-2.4 Preliminary DMS Steps 14-3

XV BACKGROUND PROCESSOR OPERATING PROCEDURES

15-1 Macro Assembler 15-1

15-1.1 Linkage with DMS 15-1

15-1.2 Assembly Examples . 15-2

15-1.3 Assembler Messages and Error Codes 15-3

15-2 FORTRAN IV Compiler 15-4

15-2. 1 Linkage with DMS 15-5

15-2.2 Compiler Examples 15-6

15-2.3 FORTRAN Diagnostic Messages 15-7

15-2.4 Run-Time Diagnostics 15-10

15-3 Library File Editor 15-12

15-3.1 Use 15-12

15-3.2 Library File Editor Error Message Codes 15-14

Revision C
November 1975

CONTENTS (CONT'D)

Section Page

XV BACKGROUND PROCESSOR OPERATING PROCEDURES ( CONT' D)

15-4 Utility Package 15-14

15-4. 1 Linkage with DMS 15-16

15-4.2 Error Message Definition 15-17

15-5 Debug 15-18

15-5. 1 Background Debug 15-18

15-5.2 Foreground Debug 15-20

"15-6 Cross Reference 15-20

15-6. 1 Input/Output Assignments 15-20

15-6.2 Unes , 15-21

15-6.3 Date 15-21

15-6.4 Cross Reference Examples 15-21

15-6. 5 Error Messages . 15-22

15-7 FORGO , 15-22

15-7. 1 Unkage with DMS 15-22

15-7.2 Execution Job Stream , 15-23

15-7.3 FORGO Error Comments 15-24

15-8 SNOBOL . „ 15-24

15-8. 1 Linkage with DMS 15-24

15-8.2 Execution Job Stream J5-24

15-8.3 SNOBOL Error Comments 15-25

15-9 RPG II 15-25

15-9. 1 Linkage with DMS 15-25

15-9.2 Compilation Job Stream 15-25

15-9.3 Execution Job Stream 15-26

15-9.4 RPG II Error Comments 15-26

15-10 Indexed Sequential Utility 15-26

?5-10. 1 Linkage with DMS 15-27

15-10.2 Execution Job Stream ''5-27

15-10.3 UTILITY Error Comments 15-27

15-1 1 Sort/Merge Utility 15-27

15-11, 1 Linkage with DMS 15-27

15-11.2 Execution Job Stream 15-28

15-11.3 Utility Error Comments 15-28

15-12 Print File 15-28

15-12. 1 Commands 15-28

15-12.2 Adding PRINTF to the Processor File 15-29

15-12.3 Examples. 15-29

15-13 VERSATEC Plotter Package 15-30

15-13. 1 VERSAPLOT - I Support Library 15-30

15-13.2 VERSAPLOT - II Support Library 15-31

15-13.3 VPLOT - Versaplot Second Pass Processor 15-31

15-14 COMPLOT Plotter Package 15-33

15-14, 1 COMPLOT BASIC SOFTWARE Library 15-33,

15-14.2 Harris Library Routines 15-35

Revision C
November 1:975

CONTENTS (CONT'D)

Section Page

XV BACKGROUND PROCESSOR OPERATING PROCEDURES (CONT' D)

15-14.2. 1 SubrouHne PLTOUT 15-35

15-14.2.2 SubrouHne STPLOT 15-37

15-14.3 Foreground Programs INTPLT and S. PLOT 15-38

APPENDIX A DMS Tables A-1

APPENDIX B Accounting Record Structure B-1

APPENDIX C System Error Messages C-1

APPENDIX D System Flags and Options D-1

APPEND:{X E System Data Module E-1

APPENDIX F Background Data Module F-1

APPENDIX G System Generation Job Stream G-1

APPENDIX H Device Bootstraps H-1

Figure

Revision C
November 1975

ILLUSTRATIONS

Page

2-5

2-1 Typical Memory Layout 2_6

2-2 Sample Active Program List ^~r

2-3 Sample Active Program List After Timeslice Switch • ^-^

3 2

3-1 Sample Master Pack Layout • • * • 'i,

3-2 File Name Uniqueness in Accounting Systems • ^"°

4-1 Changing Protection with Rename Service • ^"^^

6-19

6-1 Overlay Program • • • , 20

6-2 Multi-Phase Overlay Program - u

6-3 Multi-Level Overlay Program. - I

6-4 Multi-Phase, Multi-Level Overlay Program °-^J

6-5 Overlay Program - Control Statements • f7 Z\

6-6 Multi -Phase Overlay Program - Control Statements «... o-fU

6-7 Multi-Level Overlay Program - Control Statements. o-JI

6-8 Multi-Phase, Mu I H-Levef Overlay Program - Control Statements t-6l

6-9 Link Cataloger Output Format

6-10

6-11

6-37

Link Cataloger Table and Buffer Allocation 6-39

Code Placement Format • • ° ~^°

7-6

7-1 User Fi le Layout • •

7-2 Sample AC$NAM and AC$USR Files

12-1 Typical Disc Layout ]^-9

12-2 RTP Devices (Equipment Chassis) vT Xa

12-3 VERSA TEC Configuration Parameters '^"'^

14-1 Disc Initialization File Format ^^'"^

15-1 Versaplot Function Test J5-34

15-2 PLOT Command Format |^-^°

15-3 Sample Plot • '^"^^

X I I

Revision C
November 1975

TABLES

Table Page

3-1 File Types S-Z

4-1 General System Services 4-1

4-2 Program Status Word 4-7

4-3 Device Type Codes 4-8

4-4 Summary of FROGS Galls • 4-14

4-5 Executive Traps 4-t26

4-6 SAU Trap Control 4-27

5-1 Standard Logical File Numbers & Default Background Assignments 5-2

5-2 Standard Physical Device Numbers 5-2

5-3 VO Function Codes 5-3

5-4 Standard Disc Files 5-4

5-5 Line Printer Carriage Control 5-16

6-1 Error Message Definition 6'r18A.4

6-2 Link Loader Input Codes 6-46

6-3 Link Loader Special Action Codes 6-47

6-4 Error Messages 6-49

7-1 RATES Parameters 7-12

8-1 Acronim Error Codes • 8-6

9-1 Operator Communications Commands 9-10A

9-2 Operator Communications Error Messages 9-14

9-3 Operator Communications Modules 9-14

9_4 Physical Device Error Messages 9-17

9-5 Manual ^/O Request Messages 9-18

9-6 Foreground Error Messages 9-18

9-7 Program Abort Messages 9-19

9-8 System Boot Sense Switch Options 9-23

9-9 System Boot Control Switch Options 9-24

10-1 SREMOTE Error Messages 10-5

12-1 Terminal Control Block 12-4

15-1 Compile-Time Diagnostic Messages 15-7

15-2 Run-Time Diagnostics 15-1 1

15-3 Library File Editor Error Messages 15-15

15-4 Debug Commands 15-18

B-1 Standard Accounting Record B-2

B-2 Accounting Record Contents B-3

D-1 $OPTIONS Bits D-2

D-2 $FIAGS Bits D-3

XIII

SECTION 1
GENERAL DESCRIPTION

1-1 SCOPE

This documenf contains the basic operational and programming considerations
pertinent to the Series 6000 Disc Monitor System (DMS).

1-2 SYSTEM FEATURES

DMS is a real-time operating system that provides foreground multiprograrnming
concurrent with sequential batch processing in the background. The foreground is designed for
qpplication-reloted programs which could control a mill, process real-time data from an air-
borne missle, or interact with multiple terminal users; these programs receive highest priority
and their requirements are met first. Batch processing is never time-critical, so the background
is serviced when processing time and memory are available.

Salient features of the DMS are:

• Dynamic loading of foreground programs

• Dynamic memory allocation services

• Optional spooled I/O for any output devices

• Optional spooled job stream input from any input device

• Complete accounting system

• Full file security including read, write and delete protection

• Re-entrant foreground program capabilities

• Program priority structure that governs the allocation of memory, disc, and
processing time

• Time slicing between programs of equal priority

• Program communications via System Common or parameter passing

• Timer scheduling of periodic foreground programs

• Automatic checkpoint and restore of the background memory area

• Re-entrant editor package for terminal users

• Complete memory protection of all inactive programs from currently active
programs

• Concise job control language for batch processing

• Complete operator control over the system environment via the console
typewriter or CRT

1-1

• FORTRAN IV interface roufines for foreground services

• Sequential and direct access methods for data files on disc

• Automatic disc file compression and blocking

• Queued I/O methods for disc storage devices

• Link cataloger that prepares and outputs programs to disc in a format designed
for rapid loading and relocation

• System file manager that maintains program and data files in source and
object formats

• System generation procedure that adapts DMS to each configuration

The manner in which DMS operates and the services that it provides are described
in the following paragraphs.

1-3 FOREGROUND OPERATION

A foreground program is a program executed under control of the DMS Dispatcher
at a priority above the background. A foreground program can utilize the DMS I/O handlers
and all other system services.

1 -3. 1 Program Initiation

Foreground program can be initiated by external interrupt, by timer schedule, by
console keyboard, by remote terminals, and by other foreground programs. Selected foreground
programs can be designated as core-resident;such programs remain in core even when they are
inactive so they can be initiated quickly. Other foreground programs are designated as non-
resident; they are allocated memory and loaded from disc as they are needed. Optionally, these
non-resident foreground programs can make themselves temporarily resident. Foreground programs
which do not modify any memory within themselves can be designated as re-entrant. If multiple
requests are made for initiation of a re-entrant foreground program, then they will all share the
same body of the program and execute concurrently within the priority structure.

1 -3. 2 Executio n Priorities

When any foreground program is initiated, its execution priority is specified to DMS.
This priority determines the order in which programs are serviced, governs the allocation of
memory and processing time and determines the order in which entries are placed in the disc
queue. The priority of the external interrupt that is used to initiate a foreground program has no
influence on the execution priority of that program. In many cases, several foreground^ programs
have equal importance and require similar system response. These programs can be initiated with
equal priority values ond memory processing time will be shared between them on a time slicing
basis. Foreground program execution priorities range from 1 through 254 with 254 being the lowest
and therefore serviced last, but immediately before background batch processing, whose priority is
fixed at 255.

1 -3. 3 Program Cataloging

Any program that is to be executed under DMS must first be output onto a disc file.
This means that it must be presented In object format (as output from the Assembler or Compiler)
to the Link Cataloger which produces a load module of the program and saves it on disc. The

1-2

I Revision C

November 1975

load module consists of fhe program linked with all necessary subroutines in a basic relocarable
, format that can be loaded very rapidly.

The Cataloger also saves several program attributes and characteristics with the load
module on disc. The memory size needed to execute the program, the program type, the
execution mode, and the starting address are preserved for all programs. For foreground programs,
initial device and file assignments may be specified to the Cataloger and saved on disc.

The Cataloger technique thus provides DMS with all the information concerning each
program such that, when a foreground program is initiated, the program can be allocated memory,
loaded, relocated and executed quickly,

1 -3. 4 Background Checkpointing

Whenever the available memory space is not sufficient for a foreground program that
is being initiated, the checkpoint procedures is automatically invoked All /O initiated by
background is allowed to complete, background execution is suspended, and the entire content of
the background memory area is saved on disc. That memory is then available for foreground
programs and dynamic core requests by foreground programs. When foreground activity subsides,
and the background memory area becomes available again, the background is reloaded and its
processing resumed,

1 -3. 5 Pr ogram Communications

DMS provides several techniques through which data and status information can be
transferred from one foreground program to another. Initially, all foreground programs are
passed an initiation parameter which is loaded in the A-register when the program is started
This parameter is specified by the program making the initiation request or by the operator it
the initiation was by console keyboard.

For small quantities of data", such as program status, the Program Switch Word is a
convenient communication medium. Every active program has a switch word that it can set to
any specified value usinq a s/stem service. A corresponding servce is available that allows a
program to obtain the content of the Program Switch Word of another program.

For larger quantities of data, a reserved area of System COMMON storage is
available. The block has the dedicated label SYSCOM «"d ;hat label cannot be used by any
program for its local COMMON blocks. All programs declaring the COMMON block SYSCOM
are linked to this system communication area. For still larger quantities of data, or wherp
immediate access is not required, programs may itilize disc files for communications.

1 -3. 6 Program Restrict

A system integrity safeguard is provided by DMS in conjunction with the Program
Restrict/Instruction Trap Option. Any program operating in the Restricted Mode will be trapped
and aborted by DMS in the event that it attempts to transfer to, or alter a memory location
outside its allocated space, or that it attempts to execute a privileged instruction, such as Halt.
This feature protects DMS and all other programs from inadvertent destruction due to a program
error The restricted mode is the normal execution mode for all background and regular tore -
ground programs. Re-entrant foreground programs running in the Restricted Mode are a lowed
to access any location except the resident system. Programs which must execute special
instructions, such as input/output, or alter memory outside their allocated space, can be
cataloged to execute in the Privileged Mode.

1-3

1-4 INPUT/OUTPUT FACILITIES

All input/output operations under DMS are originated by a system service call
in which the calling program specifies a logical decive number, a function code, and any
parameters necessary to define the operation. The Input/Output Controller resolves the
logical device assignments, preforms some validity checks on each I/O request, and then
transmits the descriptive information to the appropriate device handler. The handler determines
v/hether the device is available and, if so, initiates the requested operation. Control is
then returned to the user as the I/O operation v^ill be completed using the device interrupts.
While waiting for I/O operation to be completed, a program can either continue processing
data which is not dependent on the I/O operation, or it can relinquish the use of the central
processor to lower priority programs during the wait.

The Input/Output Controller maintains the allocation and status Information for
all. devices. The card reader, line printer, paper tape devices, remote teletypes, and
magnetic tape transports are considered as allocatable devices; i.e., they cannot be used In
an orderly fashion by two programs simultaneously. Such devices are allocated to the first
program requesting to "open" the device. That program then has exclusive use of the device
until it "close:;" the device, or until the program Is terminated. The console teletypewriter
Is not allocated to any single program since it must always be available for operation
communications functions. All disc drives are considered to be shared devices and receive
special treatment. All disc Input/output requests are placed in a queue, and the queue is
serviced on a priority basis.

Symbolic output may be spooled out to any allocatable device providing that
the DMS system and the device are configured as spooled. This means that I/O from the
program is sent to a disc file, and when the "device" Is closed by the program, the file Is
copied to the specified device by a re-entrant spooling program. The disc file used In this
operation is dynamically created when the "device" Is opened, and deleted when the file has
been completely copied to t!ie device.

1-5 FILE SYSTEM CONCEPTS

The File System allows the disc storage space in a Series 6000 configuration to
be distributed among a large number of multi-sector files which can be referenced by
symbolic name. A password facility allows the user to secure a file such that it cannot
be read, wrlttcin, or deleted by any program which does not supply the proper password. In
addition. In accounting configurations, the individual user can maintain total control of his
file through use of the user-number which is attached to the file. The file creator may allow
at his discretion, other users to read, write or delete file, and each of these abilities can be
specified separately. The proper password, if any, must of course, be supplied.

A single file can be established in any specified length on any specified disc
pack in the system; and each file is always allocated contiguous sectors. The Master Disc
Directory (MDD) contains complete information on file names, file extents, file types,
passwords, and in accounting configurations, the file creator's user-number and file access
bits. The Space Allocation Map (SAM) maintains storage allocation data for each disc pack.
The directory resides on disc on the master system pack, and the individual maps reside on
their respective packs, from which they are read into memory when needed.

Any program that needs to access a disc file must first "open" the file. When a
file is opened, the entry for that file is located in the directory via a hash-coding technique
and read into memory. The password, if any. Is checked, and in accounting configurations,
the user number and file access bits are checked to determine whether the file can be read

-4

or written or neither or both by this user. The file extents are saved In memory and the
disc pock on which the file resides is located. If the pock is not currently mounted on
any drive, then the operator will be asked to mount the pack on any available disc unit.
The file type is checked to determine the blocked/unblocked status of the file. The
calling program can then access the data within the file or write new information into it.
If the file is typed as blocked, multiple records are automatically blocked into a sector.
In addition, symbolic data is compressed by removing strings of blank characters. In this
mode, the calling program has no control over physical disc sectors and can only read/write
single records. For unblocked files DMS starts the transfer of the beginning of a sector and
transfers data until the user's word count is satisfied. In the direct access mode, the calling
program must specify the record number within the file before making the data transfer
request. For blocked files, this record number Is located in the blocked data via an optimized
search technique. For unblocked files, the record number is used as a relative sector
number within the file.

Files can be created by the Link Cataloger, Library File Editor, File Manager,
ACRONIM, and any user program. The Link Cataloger creates files when it cataloges load
modules of system and user programs. The Library File Editor permits link module edititiig
of the Link Library file by performing such functions as add, delete, replace, and list. The
File Manager performs batch background file managing; provides a means of saving and
restoring files using magnetic or paper tape; and prints a disc storage map Indicating the
current files and various parameters about each. ACRONIM provides the remote terminal
user with many file utility operations such as creation, deletion, copying, etc.

Sector III of this manual describes the disc and file system in further detail.

1-6 BATCH PROCESSING CAPABILITIES

The batch processing capability of DMS allows the user to perform data reduction,
scientific computation, and program preparation in the system background without interfering
with the operation of interactive or real-time foreground programs. Batch input streams
may be spooled in from any input terminal configured in the system. This allows the
remote terminal user as well as the batch card reader to submit background job streams for
execution. Background jobs are queued based on terminal priority and control card
information.

Batch processing Is performed as directed by job control statements expressed
in a concise Job Control language. They are used to specify the program options and
device assignments and to request the execution of system and user programs. Standard
processors available for background execution are as follows.

• DMS Link Cataloger
DMS File Manager
DMS Library File Editor

• DMS Debug

• Utility Package

• Basic Assembler

• Cross Reference Program

1-5

•

• FORTRAN IV Compiler and Support Library

• RPG II

• SNOBOL

1-7 ACCOUNTING SYSTEM

The Accounting System is a functional subset of DMS which provides for device
and system utilization accounting. This is a optional part of DMS and can be configured in
or out whenever a system is generated.

In an Accounting System, DMS requires the usis of a user-number to identify all
activities. The use of this user-number within the file system has been discussed previously.
Additionally, the user-number is associated with all records of usage of the system facilities.
That is, whenever a program is run, the user-number Is used to identify the resultant
Accounting Records. Accounting Records are maintained for all devices within the system,
including all peripheral devices, system disc drives, and CPU core and time usage, The
format of these records is discussed in Appendix B.

Also provided with each DMS Accounting Configuration is the DMS Accounting
Utility Program "ACCUP" which provides a convenient means of summarizing the accounting
information and maintaining the accounting file. Section VII should be consulted for
further information on Accounting.

1-S DMS CONFIGURATIONS

Due to the extreme flexibility of DMS, and the extensive scope and power It
possesses, the Disc Monitor System can be configured into a number of different systems.
Of course, all DMS systems are tailored to the individual customer's Series 6000 hardware
configuration, which provides the variety of peripheral devices, external interrupts, hardware
options, and operation characteristics. However the DMS system itself can be supplied In
various options. These options and their effects on this document are discussed below.

The major DMS option is whether the system is spooled or unspooled. In order
to do any spooling operations, or to run interactive remote terminals, including using the
operator communications device as an interactive terminal, the DMS system must be
configured in the spooled mode. The basic unspooled DMS does not support the interactive
terminals or spooling, but does constitute a powerful monitor system useful for multiple
foreground and single batch background multiprogramming. The spooled option, which adds
approximately 1200 locations to the size of the resident DMS system, makes DMS
additionally a powerful time-sharing and high volume batch operating system.

Another option, available on ly with the spooled option. Is the accounting
system. The accounting system provides device utilization information, identifiable to
individual users for all system devices including disc and CPU. User Identity Is
established through use of a required user-number, which must be used for all operations
on the DMS system. Additionally, the accounting system provides for an extremely
flexible file security system, based on user-numbers, ^hich allows the creator of a file to
allow any combination of read, write, or delete access to be given to other users.

This manual covers the full spooled accounting configuration of DMS. However,
where applicable, items which are part of only a particular configuration are noted in the
text.

]-6

SECTION II

DMS OPERATION

2-1 SCOPE

This section is intended to give the user of DMS some general background
knowledge about the operation of the monitor system. This Includes the concept of
foreground programs, batch background, and how DMS itself operates.

2-2 PROGRAMS

DMS can run any number of programs concurrently. That is not to say that
they all can execute CPU instructions simultaneously, which would be impossible with only
one CPU, but actually that DMS selects a program to run at a given instant based on
needed resources, priority, etc. This interaction will be discussed in paragraph 2-4.
Since the outcome appears to be multiple programs executing concurrently, DMS can be
called a "multi -programming" system. What are actually running are any number of
foreground programs, and one background or "batch" program.

A "program", whether the background or a foreground, always consists of an
entry in an "Active Program List " (APL) and a block of storage called a "Program
Service Area" (PSA). Associated with the Program Service Area is a block of instructions
and data, which is a user program. Thus, as far as DMS itself is concerned, it is
executing a Program Service Area, which in turn defines the instructions to be executed
by pointing to the block of program code. The Program Service Area and Active Program
List will be discussed later in this section.

2-2. 1 Foreground Programs

A foreground program is a user program that has been catalogued (i.e., "linked")
to produce a load module on disc. All foreground programs reside on disc, and may also
become core resident when DMS is loaded. Foreground programs are those which perform
a specific task or tasks when requested. For instance foreground programs might control
processes within a factory; control various functions of a nuclear reactor; respond to external
stimuli coming from an airborne missile; control interactive terminals; or be used to compiute
some repetitive calculations based on laboratory experiments.

Under DMS, foreground programs can be activated in a number of different ways.
These include:

• Computer operator request

• Request from any other program

• External interrupt

• Time of day activation

• Periodic activation of a specified frequency

• Remote terminal user request (spooled version of DMS only)

2-1

Once a foreground program has been acMvated, it shares fime with other
programs as discussed below until it has completed its task. This could be an/where
from a few milliseconds to a several hours. A foreground program remains resident
in memory from the time it is activated, until it has completed its execution and
"EXITed" back to the system.

There are three distinct types of foreground programs under DMS. These
are Resident, Non-resident, and Non-resident Re-entrant. Resident foreground programs
are allocated memory and loaded into core when DMS is loaded from disc. They
remain resident at all times, even when they are not being used. Resident foreground
programs are used where rapid response time is necessary. That is, it saves the disc
lookup and load time when the program is activated. However, they do use up
resident memory.

Non-resident foreground programs are user tasks that reside on disc and are
allocated memory and loaded from disc whenever their activation is requested. When
the Non-resident foreground program "EXITs" to the system, its core is released and
made available for other programs. This is the most common type of foreground program.

Multiple copies of Non-resident foreground programs are allowed when the
second or subsequent request is made from another program, the operator console, or a
remote terminal. Multiple copies cannot stackup in memory via the scheduler or
external interrupt requests.

Non-resident foreground programs may, at their request, become temporarily
resident. That is they remain in core after "EXITing" to the system similar to resident
foreground programs. This is accomplished through use of the TERMIN System Service
described in paragraph 4-5.

The third type of foreground program is the Non-resident Re-entrant fore-
ground program. Re -Entrant foreground programs are those whose code is written such
that it can be concurrently executed by more than one user. That is, the code does
not modify itself, or use any fixed data storage cells within the program body. All
variable storage must be done in some external block which is associated with the
individual program. Under DMS, each user of a Re-entrant program has his own
Program Service Area. If there is more than one such user of a Re-entrant foreground
program at any given instant, then all of the respective PSA's are connected with the
same program body.

Re-entrant foreground programs running under DMS must use either the
Program Service Area or a Dynamic Core Block for all data storage to insure re~
entrancy. Such foreground programs need not be concerned with the number of
concurrent users; in fact they do not know such Information. Re-Entrant foreground
programs are written as any other foreground programs might be; with the restrictions
that they must not use data storage within the program or modify the program text in
any way. As an example, this excludes use of the BSL (Branch and Save Long)
instruction, since it modifies the program body. If a foreground program meets these
requirements, then it may be typed as a Re-entrant foreground program when cataloged
(see paragraph 6-4) and the DMS system will handle the multiple users.

What actually happens with Re-entrant foreground programs under DMS is
that the first request for such a program results in loading the program and a distinct
Program Service Area. Another request for the same program results in only the
creation of another PSA, which points to the same block of code as the other service

2-2

area. When a particular user of the program (PSA) exits, only the PSA memory is
released. DMS maintains with the Re-entrant program body a count of the current
number of users of the program. This count is incremented every time a new PSA
comes in for the program and decremented when a user (PSA) exits. When this value
drops to zero, the program body itself is removed from core. A subsequent request for
the program will cause a reloading of the program from disc.

One additional feature provided for foreground programs is that whenever a
foreground program exits (i.e., calls the EXIT or TERMIN System Service), DMS will
Close/Deallocate all of the files that may have been opened by the program, and return
all Dynamic Core Blocks that the program allocated back to the system. This feature
insures system integrity and proper resource management, and relieves the programmer
of the necessity of performing these tasks at the end of his program. This performance Is
slightly different than that for background programs, as will be shown in the following
paragraph.

2-2. 2 Background Programs

Background Programs are those user system programs which are designed
to run in a "BATCH" environment, where execution is never time -critical. All of
Datacraft's standard software processors are designed to run in background (excluding
ACRONIM and BASIC which are Re-entrant foreground programs). Thus, all compilations,
assemblies and link catalogings are run in the background.

The background memory area is a fixed size block of memory beginning
at the high end of the resident DMS and continuing to some arbitrary location in
available memory. This fixed value can be changed via the operator communications
keyin "MB" (Modify Background) as discussed in Section IX. Whenever foreground
programs are allocated memory that overlaps background, then the entire background
memory area is written to disc (checkpointed). This will only happen, of course,
after all current background I/O operations have been completed.

All background processors reside in this same area of core and start
at the initial background location. Thus there is never more than one background
program in core at any time.

A Background "Job" merely consists of a series of background program
executions. For Instance, consider the following background Job, which is a
Fortran compilation and execution.

$JOB

$FORTRAN

(Fortran program)

SCATGO

SEOJ

Initially, the background processor Job Control ("JOBCTL") is executed
to process the $JOB and "^FORTRAN statements. Next the Fortran Compiler Is
executed to process the Fortran source program. When it EXITs, Job Control is again

2-3

executed to process the SCATGO statement. Next, the Link Cataloger .s executed to
produce a load module of the user program on disc. The Cataloger calls in the user _
program for execution. When the user program EXITs to DMS, Job Control is once again
executed to process the $EOJ statement. This completes the execution of the job.

The reader will note from the above discussion, that whenever a background
program EXITs to the system, the Job Control processor is activated in its place. This is
an important difference from foreground operation. Note also that this ts the orily^
operation performed when a background processor exits. No files are closed and no
Dynamic Gore Blocks are deallocated. This allows Information from one processor to be
passed on to another processor during the execution of a background job A useful
application of this operation is in a job with multiple compilations and/or assemblies,
the Binary Output Disc file will be left open and correctly positioned from one
assembly to the next.

There is one instance, however, when background files are closed arid
Dynamic Core Blocks returned. This is when the Job Control program EXITs, which
happens after processing a SEOJ statement. Thus the end of a background job produces
the same cleaning up of system resources that is done when any foreground program
EXITs.

2-3 MEMORY ALLOCATION

As stated In the preceding paragraph, the background memory area is
fixed In size and location. However, memory for foreground programs and Dynamic
Core Blocks Is allocated as discussed in the following paragraphs. An example
of the division of memory is shown in Figure 2-1.

Whenever a request for memory comes to the memory allocator, whether
it is for a foreground program, a Program Service Area, or a Dynamic Core
Block, the allocator searches from the highest memory location (in the foreground
area) down until it finds the first available block of memory that will contain
the request. If the core block reaches down far enough, into the background area,
then background must be checkpointed as discussed in paragraph 2-2. 2 However,
if the request that would cause background to be checkpointed is actually a request
from background for a Dynamic Core Block, then the request is not processed and
notification returned to the calling program that core is not now available.

Using Figure 2-1, if a request for a core block of less than or equal to
3000 words was received by the allocator, it would be allocated from the block at
location 18000-21000 - in fact, if the request were less than 3000 words, the allocated
block would be up against the location 21000 barrier and the remaining free space
would begin at location 18000.

If a request for more than 3000 words were received. It would be
satisfied by allocating a block of the required size Immediately below location 17000.
This also would necessitate checkpointing background, since the requested block would
continue below location 15000.

2-4

Location
(Decimal)

24K

23000

21000

18000

17000
15000

8000

Figure 2-1
Typical Memory Layout

System Common
(Approximate 1000 words)

Foreground Program

(2000 words)

Available Space
(3000 words)

Foreground Program
(1000 words)

Available Space

Background Area
(7000 words)

Resident System
(DMS)

2-4

PRIORITY STRUCTURE AND PROGRAM INTERACTION

As was memtioned previously, DMS maintains an entry in the Active Program
List (APL) for each program in the system, including an entry for background, which
handles whatever background processor is active. These APL entries are illustrated in
Appendix A, but for purposes of discussion, here we need only be concerned that an entry
contains the program's priority and status word. The Program Status Word is illustrated
in Table 4-2.

Active Program List entries are ordered by priority, with background always
occupying the lowest slot, since it has the lowest priority (255). A sample Active Program
List is shown in Figure 2-2. If two entries have equal priority, then their ordering is
for the moment insignificant. This situation will be discussed in paragraph 2-4. 2.

2-4.

Context Switching

Before a discussion of how DMS selects programs can be made, we must first
define a "significant event". A Significant Event is any operation whose result could
cause a program whose execution was suspended for some reason to once again continue
execution. For instance. If a program were waiting for a certain I/O operation to be completed,
then the completion of that operation would be considered a Significant Event.

2-5

Figure 2-2
Sample Active Program Li si-

Foreground Program
"CAT"

PRI = 100

Foreground Program
"DOG"
PRI = 200

Foreground Program
"MOUSE"

PRI - 210

Foreground Program
"RAT"

PRI = 210

Background
PRI = 255

When a Significant Event occurs under DMS, the routine performing
the event executes special instructions which cause a Dispatcher Interrupt. ^ This^
Dispatcher Interrupt is the lowest priority external interrupt in a DMS configuration.
This is to insure that all interrupt processing is complete before the currently active
program is interrupted by the Dispatcher, The Dispatcher Interrupt must interrupt
program execution and must not interrupt an interrupt routine.

When a Dispatcher Interrupt occurs, as caused by a Significant Event,
DMS is said to go through a Context Switch. During a Context Switch the following
occur. Firstly, all register and program execution Information (program counter and
condition register) are stored in the currently active program's Program Service Area.
Next, the Dispatcher scans the Active Program List from the top down, examining each
program's status word until It finds a program that can be executed. This top down
scanning maintains the priority structure of DMS. If no program can be run, then the
dispatcher enters an idle loop awaiting another Significant Event which will produce a
Dispatcher Interrupt. A Context Switch is also performed, of course, wheriever the
currently active program can no longer continue, such as when it must wait for the
completion of an I/O operation.

2-6

Consider the following examples of Context Switching. Referring to
Figure 2-2, program "CAT" is active and executing. Programs 'DOG" and "MOUSE'
are both in a WAIT state, waiting for the completion of an I/O operation. If at some
time, an external interrupt occurs which signifies the completion of program "MOUSE s
I/O operation, then the program 'MOUSE" will become executable, although it will
not actually be active yet. The particular interrupt routine will consider this a
Significant Event and trigger the Dispatcher to perform a Context Switch. The Dispatcher
will scan the Active Program List and first check program "CAT" and, finding it
executable, will restart it. At a later time, program "CAT" starts an I/O operation
and desires to wait for its completion. A Context Switch will occur and the Dispatcher
will scan the Active Program List from the top. It will find both programs "CAT and
"DOG' waiting for I/O operations to complete and thus it will put program 'MOUSE"
into execution.

2-4.2 Timeslicing

Timeslicing is a feature of DMS wherein Foreground Programs of equal priority
will share execution times so that they all have available about the same percentage of
total execution time available to that priority level on the Active Program List. This is
accomplished through use of the 120 Hz Clock. A timeslice period is defined as a set
number of 120 Hz clock "ticks". This number can be modified via an operator comm-
unications keyin. (timeslicing can also be turned off by this keyln. ) The default Is two
"ticks" or l/oO of a second. Whenever this timeslice period Is completed, DMS checks
to see if there is another program which is at the same priority as the currently active
one. If so, DMS effectively moves the currently active program to a position on the
Active Program List below all other programs of that priority, declares a Significant Event,
and triggers the Dispatcher to perform a Context Switch,

2-7

Consider a conHnuation of the previous example. If the timeslice period is
over while program "MOUSE" is active, then DMS will interchange the entries for
programs "MOUSE" and "RAT", and produce a list similar to that shown in Figure 2-3.
At this point a Significant Event, and therefore a Context Switch, would occur, and
providing program "RAT" had executable status, it would be made active.

Foreground Program

"CAT"

PRl = TOO

Foreground Program
"DOG"
PR I =200

Foreground Program

"RAT"

PRI = 210

Foreground Program
"MOUSE"
PRI = 210

Background
PRI = 255

Figure 2-3. Sample Active Program List After Timeslice Switch

2-8

Revision C
November, 1975

SECTION III
DISC AND FILE STRUCTURE

3-1 GENERAL

DMS will support up to 32 disc drives per system on which can be mounted a
total number of 255 unique disc packs, of which one must remain mounted and is called
the Master Pack. On single disc systems, only the Master Pack is used. However, if at
least two disc drive units are present, then DMS supports up to 254 removable disc packs
which can be mounted on the drive (s). If is important to note that Dotacraft Series
5200 Cartridge Disc Units containing both a fixed and removable platter (Model 5204 and
5208) ore considered as two disc units for DMS operation. The fixed platter is one unit
and the cartridge is a second unit.

The space on each disc pack can be divided into variable length segments,
called disc files. Disc files may then be referenced symbolically by name during program
execution under DMS .

3-2 DMS MASTER PACK

Ail DMS configurations have a master disc pack. The master pock is pack
number one. It contains all of the system information directories, etc., to maintain
operation of the DMS system. The remaining space is allocated to user file storage.

The master pack must remain mounted on the master disc drive at all times to
Insure proper DMS operation.

The master pack contains the following items (Refer to Figure 3-1 for sample
layout giving relative sizes):

• Absolute disc loader, which resides on sector 0, used to load the resident
DMS from disc to core.

•

Background Default Assignment Storage, which is a one sector table which
contains all of the default assignments for background jobs.

Space Allocation Map (SAM) for the master pack, which maintains a
record of which sectors are used and which sectors are available for user
file storage. The SAM is always two sectors long.

• Master Disc Directory (MDD) which contains an entry for every user file
on any pack within the system. The MDD entry gives file location,
password, security, and type information.

• Background Checkpoint Area, which is the area on disc used to hold the
copy of the background memory area when background is checkpointed.

Optionally, this area can be on any other permanently mounted disc pack
in the system.

• Resident DMS - This is the disc copy of the core resident DMS system, which
is loaded by the absolute disc loader whenever DMS is loaded from disc.

3-1

Revision B
March, 1975

Figure 3-1. Sample Master Pack Layout

Sector N

User

File

Storage

825

824

Resident
DMS

665

System

664

Background
Checkpoint

Area

Space Allocation Map

62
61

Master
Disc

Directory

Background Default Assignments

Absolute Disc Loader

3-3

MULTIPLE DISC UNITS

On configurations employing multiple disc units, disc packs containing user
files may be interchanged on the "satellite" drives (all except master pock) Removable
disc packs must- all be identified by a Pack ID Number, which is between 2 and 235,
inclusive. Pack ID Numbers are established on removable packs through use ot the CLhAK
statement of the File Manager (Refer to Paragraph 6-3.14).

The first four sectors of "satellite" packs are reserved for system information,
and the remaining are available for user file storage. These first four sectors contain a
two sector Space Allocation Map, a Pack ID Number, and a special bootstrap simulator.

3-2

The bootstrap simulator causes the Series 6000 Control Console lights to be flashed in a
unique pattern if an attempt is made to bootstrap (or load) a program or operating system
(such as DMS) from the pack.

All files created on "satellite" packs are identified by entries in the Master
Disc Directory on the master pack. Whenever a file is referenced by a DMS program
that is located on a removable pack, DMS determines whether or not that pack is
currently mounted on a disc unit. If not, the computer operator is asked to mount the
pack on any available drive. When this has been done, the operator notifies the system
via a keyin that the pack has been mounted, and that program's execution can then
continue.

3-4 MASTER DISC DIRECTORY

The Master Disc Directory (MDD) contains an entry for each user disc file, in
a DMS system. Each such entry contains the following information. (A complete MDD
entry layout is given in Appendix A.)

• File Name

• Pack Number

• File Extents (First and last sector numbers of file)

• File Type

• File Access Bits (Accounting System only)

• File Password

• User-Number of user who created the file (Zero for non-accountrng systems)

• Load Module Core Requirements

• Load Module Absolute Starting Address

The latter two items are described in the discussion of the Link Cataloger,
paragraph 6-4. File Type, File Access Bits, File Password and User Number are discussed
below in Paragraph 3-5.

The particular sector in the Master Disc Directory In which the entry for a
given file is located Is determined by a hash-coding algorithm. That Is, by applying
some arithmetic operations to the file name, a relative sector number within the directory
is computed. This hash-coding allows rapid file access because It eliminates searching
more than one sector of the directory to find the entry for a specified file.

The size of the Master Disc Directory Is variable and is set at SYSGEN time.
However, a single restriction is that one parameter, the maximum number of entries In the
directory, must be a prime number. This topic is discussed further In Section XII. If
the user finds particular sectors of his directory are filling up, then it Is recommended
that the size of the directory be Increased, to allow the hashing algorithm to spread the
entries further apart. This must be done via System Generation. Refer to paragraph
12-3.6.

3-3

3-5 DISC FILES

A disc file is a contiguous segment of disc storage, given a symbolic name,
optionally a password, and in accounting systems, a user-number, all of which ore used
to identify the file. Disc files can be any size from one sector up to the maximum
capacity of the disc pack. Once a file has been created, its size cannot be changed.
The file can only be deleted and re-created.

When a disc file is to be created, the user must specify the name, password
(if any), file type, size, disc pack number on which the file is to be located, and, in
accounting configurations, the file access bits, if any. Initially, the file name, password,
and user -number are checked against existing files, and if the name Is not already in use,
the DMS system finds a block of contiguous disc space of the required size by searching
the Space Allocation Map of the specified pack. A first-fit technique is used. That is,
the Space Allocation Map is scanned from the beginning until the first available slot is
found. An entry in the Master Disc Directory for the file is then mode, and file creation
is complete. The allocated disc space is not cleared when the file is created. An error
condition or message is returned to the user if, for any reason, the file cannot be created
as specified.

As described above, DMS disc files are allocated in units of the Space
Allocation Map. The SAM is always two sectors long and each bit is used to represent
one or more sectors. Thus the SAM size is 2 x 112 x 24 or 5376 bits. When a disc
pack has more than 5376 sectors, as most do, then each SAM bit is used to represent
more than one sector. For example, on normal density (204 cylinder) Datacraft Series
5200 Cartridge Disc units, there are 8160 sectors. Thus for these discs, each SAM bit is
used to represent two sectors. This limits disc storage allocation to units of two sectors.
Thus if the user asks for a file of three sectors, actually four sectors of disc space are
allocated; the user getting three with one wasted. On larger, moving head multl -layer
disc units, each space allocation bit may represent more sectors.

3-5. 1 File Security

DMS file security is maintained through use of a four character password, and
additionally in accounting systems, a user -number and read, write and delete access bits.
All of this information is stored in the Master Disc Directory entry for the file.

In non-accounting systems, file system integrity is maintained through use of
the password. A password can be any string of one through four alphanumeric characters,
provided the first is alphabetic. When a password is supplied with file creation, or is
later added through a file Rename operation, then all references to the file must supply
the correct password. That is, when the file is OPENed for I/O operations, or attempts
are made to Delete or Rename the file, the correct password is required.

An additional feature of the DMS file system allows multiple files to have
the same name, so long as they have unique passwords. That is, within one DMj system,
there can exist file CAT with password X and another different file CAT with password
ABCD. However, If there exists a version of the file without a password, which is
considered a "public" file since anyone can access the file regardless of the specified
password, then there can exist no other files with that name. For example, if the files
CAT existed at stated above, then another file CAT with no password, (i.e., o "public"
version) could not be created. Correspondingly, if there existed a file DOG without a
password, then no other files named DOG could be created, even when a password was
given.

3-4

In accounting versions of DMS, there exists a much more extensive file
security system, in addition to that discussed for passwords in the previous paragraph.
This involves the use of user-numbers and file access bits. When a file is created in
an accounting system, the user-number of the program creating the file (refer to bection
VII) is included in the directory entry along with any file access bits that may have been
supplied by the creator. If no access bits are set when creating the file, then the tile is
totally private; that is, it can be Read, Written, or Deleted/Renamed only by programs
executing with the creator's user-number. The creator may specify, however, thay anyone.
else be allowed to perform a particular operation of the file. For instance. Read, by
setting the appropriate access bit(s). There is a distinct access bit for Reading, tor
Writing, and for Deleting/Renaming the file. Exact specifications of ''j^ese bits is
discussed in the appropriate paragraphs of Sections IV, VI and the ACRONIM General
Specification (AA61681 -00).

An extension of the use of multiple file names in addition to that discussed^
above in conjunction with passwords, is provided in an accounting system. F'"!, ^Je
difference between "public" and "private" files for accounting systems must be defined.,
A "public" file in this context is any file which has one or more of the read, write, o^
delete access bits set. A "private" file is one which has none of these set and can b^
referenced only by the original creator. Within the restrictions discussed above tor
passwords, if there exists a valid name and password combination, there can then exrst
any number of private files employing this file name and password, so long as fhe user
numbers are different. If, however, there is a valid name/password combination that is,
"public" (has any access bit set) then there can be no other occurrences of this name
and password together. For example, consider a file ABC with password X which is
totally private (i.e. has no access bits set) with user -number Nl. Then users NA NJ,
etc can all create files ABC with password X provided they are all totally private.
However, no one would be allowed to create a file ABC having password X with any ^
access bits set, which would be a public version. Correspondingly, if there existed til?
DEF with password Y having public read access set, then no one else could create a
file DEF having password Y. Figure 3-2 gives a generalized description of what can ai^d
cannot exist.

3-5. 2 Passwords on Load Modules

Whenever a load module (program) is created on disc by the Series 6000
Link Cataloger, it is given the special password "GORP". The purposes of this are two-
fold One is that it allows users to create other data and word files of the same name,
i e.', it creates a non-accounting type private file instead of a public one. Second, i!t
prevents accidental destruction of program files by requiring use of the password when _
doing writing or deleting operations. The System Loader uses the password GOKP when
reading any load module from disc. Hence, the user need not be concerned with its
presence except when a purposeful attempt at deletion or renaming of the program is
desired.

3-5. 3 File Types

When a file is created, the user specifies a File Type. As far as DMS
operation is concerned, file types 1, 4, 5 and 6 are all equivalent. This file type
distinction Is provided soley for purposes of the individual installation. DMS does,
however, differentiate file types 2, 3, 7, 8 and 9. These distinctions are required to
allow the system to determine the types of load modules and correctly load program files.
The meaning of various File Types is given in Table 3-1.

3-5

Figure 3-2
File Name Uniqueness In Accounting Systems

Given the same
file name If

there exists ^

Then the
following is: ^

File w/o
Password
No Access
Bits Set

File w/o
Password,
Some Access
Blt(s) Set

File with
Password
No Access
Bits Set

File with
Password,
Some Access
Bit(s) Set

No password w/o
access bits and
different user

Valid

Invalid

Valid

Invalid

No password with
access bits and
different user

Invalid

Same password
w/o access bits
and different
user

Valid

Invalid

Same password
with access
bits and
different user

Invalid

Different
password w/o
access bits &
different user

Valid

Invalid

Valid

Different
password with
access bits &
different user

Invalid

Valid

Different
password w/o
access bits &
same user

Invalid

Valid

Different
password with
access bits &
same user

Invalid

Valid

3-6

Revision C
November 1975

Table 3-1
File Types

3
4
5
6
7
8
9

User Data or Work File

Background Relocatable Load Module

fockground Absolute Load Module

Object Library File

Source Library File

System Work File
Resident Foreground Load Module
Non-Resident Foreground Load Module
Re-entrant Foreground Load Module

An additional file type specification is provided through use of the blocked^
or unblocked types. Any of the file types I, 4, 5 or 6 can additional y be speofied as
blocked. Once a file has been created as blocked, then all accesses to the file are
through the resident DMS Blocked File Handler. Blocking of files provides increase
disc Lrage density by packing multiple records per disc sector Additionally symbolic
records have contiguous blanks replaced by a b ank suppression character on the disc file
providing increased file capacity. For example, normal symbolic assembler source card
images ?an be packed about 8-10 images per sector by blocking techniques while ,f the
data were written in an unblocked file, one image per sector would be written. Further
advantages of blocked files are given in Paragraph 3-5.4

A further distinction within blocked files is provided by a type designation
of spool files. Spool files are those dynamically created by the system to hold input and
output spool files. Input spool files providing background jobs are named S:nnnn where
nnnn is an ascending decimal number. Output spool files generated by any program are
named S#nnnn where nnnn is again a decimal sequence number. If a file is typed as
spooled, then the Foreground Output Spooler will delete it when ,t has comp eted the
dumping of the file. Correspondingly, input spool files are automatically deleted by
background when the job has been completed.

Yet another file type designation available under DMS is the Core
Resident Directory option. When a system is generated, a table of variable length
is created in memory to hold those Master Disc Directory entries the user feels are
accessed frequently enough that the extra disc access to the Master Disc Directory
should be eliminated. For instance, if a particular configuration has a d'sctile
(possibly a load module file) that was opened, say once a second, then '^ might be
advantageous to have its directory entry reside in ^^;e 'n-core directory table o f'^ n°|j
?he disc access involved in the directory look-up. When a data or program file is created.

3-7

Revision C
November 1975

it can be specified thai its directory entry is to be core resident. Refer to Section VI
on data and program file creation. Note that this in-core directory table must be able
to hold all directory entries that are created as "Core -Resident". The user should be
careful not to overflow this table, which would cause a rejection of a file creation of
this type.

Any of the above file types may also be classified as being Permanent files.
A file which is typed Pennanent is not moved during pack compression. A typical use of
a Permanent type file would be to cover and flag a bad sector on a disc peck.

3-5.4 File Accessing Methods

Whenever a disc file is "OPENed", which is required before a program
can access the file, the file password is checked. Additionally, in Accounting Systems,
the user -number and file access bits are checked and saved to insure that the user is
allowed only appropriate access to the file.

Records written to unblocked files are always written beginning at
sector boundaries. Thus, if all records written are less than or equal to 112 words in
length, one record will be written per sector. When unblocked files are read, the
record length transferred is determined by the word count of the read request, not what
was written to the file. Thus, for example, if two 30-word records were written to
unblocked file, and the first was read with a word count of 224, the data transferred
would be the first 30 -word record, followed by 82 zeros, followed by the second 30-word
record, followed finally, by another 82 zeros. End-of-file marks on unblocked files are
written as hardware end-of -files, and occupy a full disc sector.

On blocked files, records are written continuously on sectors, with a
software end-of -record mark between each record. Records may spill across sectors as
necessary, but all 112 words of a sector are used. Additionally, if a record is written
with a Symbolic Write request, then strings of multiple blanks will be replaced bv a
single blank suppression character and trailing blanks ignored. In contrast to unblocked
files, which always reads the specified word count, when a record is read frorn a
blocked file, at most one previously written record is transferred. On Symbolic Read
requests, if more words are requested than were in the record written, the remaining
positions are filled with blanks. End-of-file marks on blocked files are handled by
software, and occupy one word of a sector.

File manipulative commands can be performed on both blocked and
unblocked files. These include advance record, backspace record, advance file,
backspace file, and rewind. One difference, however, is that for unblocked files, if the
word count of the record(s) being bypassed is greater than 112 then this word count must
be specified on advance and backspace record commands.

Random read/write capability is provided through use of the Set Current
Record Address Function, which sets the file pointer to a specific record within the
file. For unblocked files, this Record Number is actually just a relative sector number.
For blocked files, an actual record number is used. Based on record numbers stored in
each block of a blocked file, an optimized Iterative search technique is employc;d to
locate the specified record and set the file pointer to it.

3-8

Revision C
November 1975

Random access writing of blocked files is not normally valid. That is,
blocked files function is similar to magnetic tape. Hov/ever, an Edit Write function code
is available for blocked binary records, allowing a specified record to be over-written
provided the original word count and new word count are identical.

3-9

Revision C
November 1975

SECTION IV
SYSTEM SERVICES

4-1

GENERAL

System services perform fhose system functions that are required to serve all
programs executed under DMS. These services are performed by resident system sub-
routines that can be accessed using the Branch and Link Unrestricted (BLU) instruction.
A Service Linkage table for all services is contained in memory locations through '37.

The first six services are provided in a manner compatible with the Series
6000 Disc Operating System (DOS) such that background processors can be executed
interchangeably with either system.

Table 4-1 lists the system services and their functions.

Table 4-1
General System Services

Linkage Address (Octal)

1
2
3

14
15
16
17
20
21

Description**

BLU SABORT
BLU $]/0
BLU $EXIT
BLU $HOLD

BLU SCHAIN
BLU SINFO
BLU $WAIT
BLU $SFUNC
BLU SCONV
BLU SFROGS
BLU SSYSTER
BLU STERMIN

BLU SASSIGN
BLU $DCM
BLU $UNTRAP
BLU SFPACK
BLU SO/M
BLU $C/RTN

System Services Function

Abort calling program

Request ]/0 function

Terminate calling program

Output operator message and
suspend calling program

Load program segment

Return system information

Wait until flag is reset

Perform special system function

Execute number conversion

Special foreground services

Restricted system services

Tenminate without leaving
memory

Dynamic ]/0 device assignment

Dynamic Core Manager

Background & card control

Find specified disc pack

Output Operator Message

Contingency Return

^The Cataloger utilizes only the first three characters of the "BLU name", i.e.,
"BLU $ABO". I

4-1

Revision C
November 1975

The contents of the registers are indeterminate upon return from any system
service except where used to return the results of the service as indicated m h.s
document. It is the responsibility of the calling program to save any essential data m
the registers before calling a system service.

4-2 ABORT SERVICE

The ABORT service provides a means whereby the calling P''°g''<=';" ^°" ^^^^
abruptly terminated and an appropriate notification output to the l^^'''^^' ' /^^^^^ue^,
function is invoked by DMS when a program error Is detected (such as an I/O request
with an invalid functfon code or logl'cal file number), when an OP«-^- .Commun-catjons
command to abort a program Is received, or when this service ,s ^^^l^^^- J^^ ^^^^^"^
message that is output to the program's output device or file is of the format.

XXXXXX: ABT cc ;a) aaaaaa

where: XXXXXX is a program name; aaaaaa is a relative program

address; and cc is a unique error code.

After the message has been output, DMS then closes all logical files that
were opened by the aborted program and otherwise proceeds with the termination process.

When any background program is aborted, the Job Abort flog is set such
that remaininci control statements associated with that job are ignored and J°b Con "■ol
searches for the corresponding $EOJ statement in spooled configurations or he next SJOB
or $EOJ in unspooled systems. (If the Job Stream is assigned to the console tele-
typewriter, a $JOB is not required. ) When a foreground program is aborted only the
cu'Jrent execuHon of the program is aborted, and nothing is done to prevent reinitiation
of the same program. No interrupts are enabled as a result of an ABUKI.

Assembly Language Call

BLU $ABORT

4 -2 A Contingency Return

The C/RTN service provides a means whereby a foreground or background program
may regain control upon an SAU trap or system abort. The only requirement is that the programs
must supply the service password in the D register when the service is called. The password
consists of 6 ANSCII characters, and Is denoted below by "KEY". The user program is allowed to
be qiven control of up to 32 aborts, the 33rd abort is unconditionally fatal. Following an operator
(eight OPCOM or terminal user) abort, any abort (including a second operator abort) is also un-
conditionally fatal. After the user program is given control of an abort, the next abort is total
unless the user again makes a call to C/RTN.

The user program is allowed to be given control of an unlimited number of nonaborting
SAU traps. C/RTN requests are made via the following calling sequence:

4-2

Revision C
November 1975

TMD

="KEY"

TLO

USRRTN

BLU

$C/RTN

DATA

PARAMETER

D = service key

K - address of user routine to v/hich

control is to be given

USRRTN

DATAO
DATA

The user may specify whether the system is to return control to the user only in
the case of an abort, or in both cases of aborts and non-aborting SAU traps. The user may
additionally specify v/hether system abort messages are to be printed by the system. Valid par-
ameter values and their meaning are given below.

l!,i case of an abort, the system will branch to USRRTN4-2 with USRRTN containing
the system abort code and USRRTN+1 containing the abort location in bits 15-0.

In case of a non-aborting SAU trap, the system will branch to USRRTN+2 with

USRRTN containing the SAU error code with bit 23 set. USRRTN+1 will contain the trap

location in bits 15-0 and the C register in bits 19-16. The user may return to the npn-KJbort-ng

SAU trap location by restarting all registers to the values contained upon entry to U5RR1N and

executing a BRL*USRRTN instruction.

Definition
Parameter

n Remove previous C/RTN call entry. ,, , ^ . c u ^

? Do not inhibit abort messages, branch to USRRTN+2 in case of an abort.

2 Do not inhibit abort messages, branch to USRRTN+2 for both aborts

and non -aborting SAU traps. ^ „ , . r „

3 Inhibit system abort messages, branch to USRRTN+2 only m case of an

4 InhTbft system abort messages, branch to USRRTN+2 for both aborts and

non-aborting SAU traps.

4-3

INPUT/OUTPUT REQUESTS

ALPHA

The I/O Control System performs all I/O functions on a priority interrupt
basis, providing the ability to overlap I/O operations are internal processing. I/O
requests are made with logical file numbers; physical devices and disc files may be
assigned to logical file numbers through Job Control and the Cataloger for backgrpund
and foreground programs respectively. I/O requests are made via the following sequence
of instructions:

TLO PARLIST (K) = address of parameter list

BLU Sl/O Call I/O control

Transfer has been initiated and will
be performed on an interrupt basis
concurrent with processing.

XX ^logical file YY -function code

Word count

Buffer Address

Reserve n words or storage

PARLIST

DATA

'XXYY

DATA

DAC

BUFFER

BLOK

4-2A

If a device is busy when a request is received, the calling program is
placed in the "waiting" state until the device becomes available. When the device is
available, the request is initiated such that it can be completed using the device
interrupts. Control is then returned to the calling program (at ALPHA+2) with the
condition register set to "not negative". A BON at ALPHA+2 is not necessary for
DMS; it should be used, however for DOS.

When any program must determine if an outstanding I/O function has been
completed, it should request a status test. The status test function will place the
calling program in a waiting state until the I/O function being tested has been
completed. When the I/O function has been completed, it next checks for device
errors and, if necessary, performs complete error processing and recovery. Finally, when
the i/O function has been completed, the status test function returns control to the
calling program with pertinent data regarding the referenced function in the accumulator
(End-of-File, word count not complete, etc. ).

Functions not requiring a parameter list (word count and buffer address) may
be executed via the following sequence:

ALPHA TNK 'XXYY (K) =logical file/function code

BLU $l/0 Call I/O control

This sequence may be employed to test status, open a file, etc. The
acceptable function codes for each device and their precise definitions are provided in
Section V of this document.

4-4 EXIT SERVICE

The EXIT service provides the normal means to terminate execution of a
program. The EXIT function closes all logical files which have been opened by the
calling program and awaits completion of all I/O Initiated by the terminating program.
When a background program is terminated, Job Control Is reloaded and executed. When
a non-resident foreground program Is terminated, its allocated memory Is released for use
by other programs, and its entry Is removed from the list of active programs. When a
resident foreground program Is terminated. Its entry is merely removed from the active
program list.

Assembly Language Call FORTRAN Call

BLU '.EXIT CALL EXIT

4-5 TERMIN SERVICE

The TERMIN service Is identical to the EXIT service described above
except that it results in the foreground program remaining In core In its allocated
memory area. This call is redundant for background or resiJent foreground programs.
Foreground programs using this service can later be reinitiated by normal means with the
exception that they will not be loaded from disc. A program which has used this
service can later do a normal EXIT when it is again active.

Assembly Language Call

BLU $TERMIN

4-3

Revision A
May, 1974

4-6 HOLD SERVICE

The HOLD service allows a program to output a message to the console typewriter and
suspend execution pending on operator response (refer to Operator Communications, Section IX).
The typewriter message has the following format:

program: message text

where- program consists of one to six ANSCII characters representing the program name
for foreground programs or the characters "BAKGND" for any message originated by a background
program, and message text is 1-15 ANSCII characters.

The following calling sequence is required to utilize the HOLD service:

Assembly Language Call FORTRAN Coll

TMK MESSAGE PAUSE XXXXXX

BLU SHOLD OR

STOP XXXXXX
MESSAGE 'XX" ^"message text" This causes HOLD with STOP or PAUSE,

plus the six-character message.

where: XX is the octal word count of the text message (Maximum^S).

If XX is zero, there will be no message, but the execution of the program is suspended.

EXAMPLE:

TMK MOUNTl

BLU SHOLD

MOUNTl '05 ="MOUNTA3TAPE"

Assuming the call is made by a background program, the background will be suspended
and the following message output:

BAKGND: MOUNT A3 TAPE

4-6A O/M SERVICE

The O/M Service allows a program to output a message to the program's appropriate
List Output File; or Device. For background programs this is the List Output Logical File (06),
and for foreground programs this is the terminal at which the program was initiated. The type-
writer message has the following format:

Program: message text

Where message text is 1-15 ANSCII characters. The following calling sequence is
required to utilize the O/M service:

As sembly Language Call

TMK MESSAGE

BLU $0/M

MESSAGE 'xx = "Message text"

4-4

Revisfon A
May, 1974

Where: xx is the octal word count of the text message (Maximum = 5).

4-7 CHAIN SERVICE

CHAIN allows a large program to be segmented into multiple load modules and "chain
loaded" under program control for execution. Different Chain modules may reference a
COMMON data pool and may call each other in any order. The last executable module should
call EXIT. The CHAIN calling sequence is:

Assembly Language Call FORTRAN Call

BLU $CHAIN CALL CHAIN (6HXXXXXX)

DAC ="XXXXXX"

where: XXXXXX is the identification of the module being called. For additional
information, refer to the Link Cataloger, Section VI.

4-4A

Revision C
November 1975

4-8

INFO SERVICE

INFO provides any processor with system information such as date, lines per page,
options, flags etc. An assembly language information request is as follows:

TOK
BLU

Value of n

2
3

5
6

9
10
11

n
SINFO

Result

The 24-blt Option word is returned in the A register. If the BLU
$INFO request is from a background program, the word returned
in the A register is the logical "OR" of the current background
option word (see section 6-2.6) and any options cataloged with
the program (see section 6-4. 2), If the BLU $INFO request Is
from a foreground program the word returned In the A register
consists of only those options cataloged with the program (see
section 6-4. 2) and the remaining bits are zeroed.

The nine-character date is returned in the E, A, and I register,
respectively, three characters per register. See F'aragraph 6-2.4.

The lines-per-page integer is returned in the A register. See
Paragraph 6-2. 5.

The 24-bit Flag word is returned in the A register. See
Paragraph 6-2, 7.

The current six-character job name is returned in the D register.

The current run time is returned in the D register as a double
precision Integer in Accounting Systems only. Time is expressed
in milliseconds since start of job. In non-accounting systems,
this call returns zero.

The background -low address is returned In the E register and
background-high address is returned in the A register. The
Memory-high address is returned in the J register.

The negative of program high for the current background pro-
cessor is returned in register I.

Invalid. A program abort will result.

The contents of register D are saved as "Start -of -Job" time.

The previously saved "Start-of-Job" time is returned in
register D.

The current time of day is returned in register A. It is expressed
as an integer representing tenths of seconds since midnight.

4-5

¥-9

SFUNC SERVICE

The SFUNC service performs several special sysfem functions that can be
equested by both foreground and background programs. A specific function is selected
jsing the following general calling sequence.

Assembly Language Cal

TME

TMA

BLU

$SFUNC

DATA

where: pi, p2 contain the parameters that are defined uniquely for each
Function and n specifies the required function as shown in the following table.

Value of n

1
2

Result

Sets the Program Switch Word of the calling pro-
gram to the value of p2.

Fetches the Program Switch Word of the program
identified by the six-character name contained in
pi and p2. If the program is active, the Program
Switch Word of the specified program is returned
in register A and the Program Status Word is
returned in (E). The format of the Program Status
Word and the corresponding system status conditions
are defined in Table 4-2.

Disables the SAU overflow interrupt trap_ during the
execution of the calling program overriding the
option specified when the program was Link Cata-
loged. (TYPE=SAUT). The parameters pi and p2
are meaningless for this function.

Re-enables the SAU overflow interrupt trap during
the execution of the calling program. This function
terminates the effect of the preceding function.

Determines the peripheral device number of the ^
device assigned to the logical file core contained in
bits 11-6 of p2. Upon return, (I) contains the
address of the File/Device Control Block, which^
corresponds to the specified file code. The initial
word of the F/DCB contains the peripheral device
number in bits 5-0. If this device number is zero,
then the file code is assigned to a disc file; the
ANSCII name of the file can be obtained from words
two and three (addressed as 2,1 and 3,1).
Register A contains the device type of the assigned
device according to Table 4-3. If the logical file
is not assigned to any device, then the service
returns with (I) = 0. __^_

4-6

Example:

TMD

BLU

DATA

="TEST lA'

$SFUNC

When control is returned after executing this call, the E register will
contain a -1 if the program TESTIA is inactive. If TESTIA is active, then E will
contain a value other then -1 and A will contain Its Program Switch Word.

Table 4-2
• Program Status Word

Bit

823 =1
B22 =1

B21 =1

B20 =1
B19 =1
B18 =1

B17 =1

B16 =1

B23-19=0
B 17-0=0

Indication

Checkpointed
Waiting

Suspended

Awaiting Initiation
Awaiting Allocation
Abort Inhibited

Abort Pending

Terminated

Executable

Comments

Program has been checkpointed on disc (BAKGND
only).

The program is discontinued until a specified flag
becomes non-negative. The flag assress is contained
in bits 15-0.

The program has been discontinued indefinitely. An
Operator Communications command is required to
resume its execution.

An initiation request has been mode for the program,
but it has not yet been processed.

The program is a candidate for foreground memory
allocation.

The program is undergoing an initiation or term-
ination sequence during which an abort cannot be
processed.

An abort request has been made for the program,
but it has not been processed.

Program has exited via TERMIN service.

The program is contending for computer processor
time which it will be allocated according to
priority.

4-7

Revision B
March, 1975

Table 4-3. Device Type Codes

Code
(Decimal)

Type of Device

Disc

Console TTY

Remote TTY

Remote CRT

Paper Tape Reader

Paper Tape Punch

Line Printer

Card Reader

Card Punch

Mag Tape

Synchronous Interface

Real Time Peripheral Equipment

Incremental Plotter

Printer/Plotter

4-10

WAIT SERVICE

The WAIT service allows a program to relinquish all processing time until a
flog word is set to a positive or zero value by some other program or interrupt routine.
When this service is called by a foreground program, control is transferred to another fore-
ground program or to the background as dictated by program priorities. When called by a
background program, the system inters the null state until an interrupt occurs, enabling some
program to resume execution.

The WAIT function that is associated with this service is used extensively by the
I/O Control System and other DMS routines to provide multiprogramming. For example, when
an ]/0 request cannot be initiated for a program because the required device is busy, then
IOCS invokes the WAIT function and the program is discontinued until the busy flag associated
with the required device is reset. The WAlT service allows this function to be adapted to more
general applications. It can be used when a data processing program must wait until a data
acquisition foreground program has input some quantam of data (and then resets the flag).

Assembly Language Call

TLO FLAG

BLU $WAIT

4-8

where: FLAG is the flag word and can reside in the calling program or
in SYSCOM.

4-n CONV SERVICE

The CONV service performs the number conversion functions. The service
is utilized with the following calling sequence:

Assembly Language Call

TMA VALUE

BLU SCONV

DATA n

VALUE DATA X

where: n determines the type of conversion.
X is the value to be converted.

Value of n

Function

The value in (A) is converted to its decimal
ANSCII equivalent and returned in register I, E
and A. A negative is Indicated by (-); a positive
sign Is indicated by a blank space (K).

(I) = Sign, K 1st digit
(E) = 2nd, 3rd, 4th digits
(A) = 5th, 6th, 7th digits

The value in (A) is considered to be a 24-bit
unsigned integer, and is converted to its octal
ANSCII equivalent. The result is returned in
registers I, E and A.

(I) = K 1st, 2nd digits
(E) = 3rd, 4th, 5th digits
(A) = 6th, 7th, 8th digits

4-12

SPECIAL FOREGROUND SERVICES

The foreground system services perform those functions required to coordinate
foreground activity. These services can also be called by background programs. The
general calling sequence for foreground services is as follows.

Assembly Language Call

TMR parameters

BLU $FROGS

DATA n

FORTRAN Call

Call FROGS (n, parameterl,parameter2,. . . )

4-9

Revision C
November 1975

v/here: n Identifies the specific foreground system service parameters that
ore dependent on the specific service. These services and the corresponding value of n
are described in the follov/ing paragraph, and summarized in Table 4-4.

4-12. 1 Program Initiation

Any foreground program executing under DMS has the ability to initiate
another foreground program which can be specified to operate at a higher, lower, or
identical priority to the calling program. The calling sequence for this function is as
follows:

Assembly Language Call FORTRAN Call

TMD ="program" Call FROGS (l,6HPROGRA,priority, parameter)

TOT priority

TMK parameter

BLU SFROGS

DATA 1

„here: "program" or PROGRA identifies the program name in six ANSCII
characters, priority specifies the execution priority and must range between 1 and 254^
and "parameter" specifies a 24-bit value which is passed to the specified program and
loaded in the A-register when it begins execution. Upon return, the A-register will contain
the address of the APL entry for the program being initiated or -1 if the APL list was tull.

Control is returned to the calling program once the initiation procedure has
been started, but not necessarily completed. In accounting systems, the user number of
the calling program is automatically used as the user-number for the program being initiated.

Example:

TOI 1 Call FROGS (l,6HDTALOG, 1,5)

TMD ="DTALOG"

TOK 5

BLU SFROGS

DATA 1

• • • • • •

This example will initiate program DTALOG to execute at priority 1 with
parameter of 5.

4-12.2 Foreground Interrupt Handling

Foreground system services are provided to allow program control of selected

priority interrupts those reserved for foreground program initiation during system

generation. To utilize this type of interrupt, a program must be first "connected" ^o ''ne
interrupt level i.e., a software linkage must be established such that the program will be
initiated when the interrupt becomes active. The CONNECT service used to make this
linkage has the following sequence.

4-10

Assembly Language Go 1 1

TMD

= '■ program

name"

TOI

■xyy

TOK

BLU

SFROGS

DATA

parameter

where:

"program name

the program.

FORTRAN Call

Call FROGS (2,6HPROGRA, 'xyy,,n,parameter)

"program name" - consists of six ANSCII characters that identify

X - represents an octal digit specifying group
number.

yy - represents two octal digit specifying level
(within appropriate group).

n - represents the system priority at which the

specified program will be executed; must range
between 1 and 254.

parameter - represents a 24-bit value to be passed to

specified program as parameter at initiation.

The CONNECT service disables and arms the specified level before
returning to the calling program. When the connected program is initiated, the user-
number for Accounting Systems will be the same as that of the program making the
CONNECT call.

The ENABLE service can be used to enable the priority interrupt so that it
can be activated by an external signal. The ENABLE function first verifies that the
specified interrupt is valid and that o program has been connected to it. If these
conditions are met, the ENABLE function enables the interrupt and returns to the calling
program. The calling sequence to enable an external interrupt is as follows.

Assembly Language Call

TOI
BLU
DATA

interrupt
SFROGS
3

FORTRAN Call

CALL FROGS (3, interrupt)

CONNECT.

where: interrupt identifies the interrupt group and level as described for

The DISABLE service disables the specified priority interrupt and thereby
prevents its activation. The DISABLE funcj-ion first verifies that the designated interrupt
is valid and then disables the interrupt. The calling sequence is as follows:

Assembly Language Call
TOI interrupt

FOR TR AN Call

CALL FROGS (4,;nterrupt)

4-n

BLU
DATA

$FROGS
4

The RELEASE service removes the software linkage extablished by CONNECT
and disables as well as disarms the specified interrupt. A RELEASE must be issued
before another CONNECT can ne made to the same interrupt level. The calling
sequence for RELEASE is as follows:

Assembly Language Call

TOI interrupt

BLU $FROGS

DATA 5

FORTRAN Call

CALL FROGS (5,interrupt)

Example:

TMD

="ALARM1 "

TOI

'121

TOK

BLU

SFROGS

DATA

TOI

'121

BLU

$FROGS

DATA

CALL FROGS (2,6HALARM1, '117,1)

This example connects program ALARMl to the interrupt of group 1, level
17, and then enables that interrupt. When the interrupt becomes active, the program
ALARMl will be executed at DMS priority 1.

The user should consult Section XII, System Configuration, for information
on specifying certain external interrupts as usable by these services.

4-12.3

Timer Scheduling

The timer scheduler provides the capability of repetitively executing
foreground programs at fixed time intervals. The SCHEDULE service con be called by
any program to add any foreground program to the timer schedule. The calling program
must specify the program name, the activation intercal in 120 Hz Clock counts, and its
execution priority as shown in the following calling sequence. The user number in
Accounting Systems will be the same as that of the calling program.

Assembly Language Call

FORTRAN Cal

CALL FROGS (6,6HPROGRA,priority,
timer counts, parameter)

TMD =" program

name"

TOI priority

TOK timer counts

BLU $FROGS

DATA 6

DATA user parameter to be passed to "program name"

4-12

If this program has already been entered, the condition code is set to a
negative (-) condition. If the timer schedule is full, the condition code register Is set
to a zero (0) condition before returning to the calling program and the request is ignored.
Otherwise, the program is added to the schedule and the condition code register is set
to a positive (+) condition.

TMD ="SCANX" CALL FROGS (6,5HSCANX,5,50,100)

TOI 5

TOK 40

BLU $FROGS

DATA 6

DATA 100

In this example, the program SCANX will be executed at priority 5 once
every 40 timer counts. There are 120 timer counts per second. The parameter passed
to SCANX is 100.

A DELETE service is also provided that removes the specified program from
the timer schedule. This service is called with the following instruction sequence.

Assembly Language Call FORTRAN Call

TMD ="program CALL FROGS (7, 6HPROGRA)

name"
BLU SFROGS

DATA 7

* • • • • «

An additional service is provided to cause a foreground program to be
initiated after a specified delay. To use this service, the calling program must give the
number of timer counts in the future at which time the program is to be Initiated. By
using this service in conjunction with the INFO time of day service, a program can cause
another program to be initiated at a specific time of day.

Assembl y Language Call FORTRAN Call

CALL FROGS (1 0,6 HPROGRA, priority,
timer, parameter)

TMD

=" program

name"

TOI

priority

TOK

timer counts

BLU

SFROGS

DATA

parameter

If this program has already been entered, the condition code Is set to a
negative (-) condition. If the timer schedule is full, the condition code register is set
to a zero (0) condition before returning to the calling program; and the request is
ignored. Otherwise, the program is added to the schedule and the condition code
register is set to a positive (+) condition.

A WAIT service is also provided to enable the calling program to place
itself in a suspended state for a specified Interval. This interval Is specified as a number
of timer counts. This service is called with the following sequence:

4-13

Revision B

March, 1975

Assembly

Language Call

FORTRAN Call

TOK

timer-counts

CALL FROGS (1

BLU

SFROGS

DATA

4-12.4 System Common

Accessing

The label SYSCOM is reserved for a special common storage area in upper memory by
the DMS. This area provides a communications region for programs executing under DMS. The
size of the SYSCOM area is established during system generation.

Any program that needs to reference this area must contain a common statement specifying
the block name SYSCOM. The proper address for SYSCOM references will ^^en be constructed
by DMS when the program is loaded. Any program can then extract data from SYSCOM and pro-
cess it A program operating in the Restricted Mode cannot alter memory outside its allocated
area and thus cannot normally modify the contents of SYSCOM. However, a pair of foreground
system services are available that provide a restricted foreground program with temporary write-
access to SYSCOM. The PROVIDE service modifies the contents of the upper limit register tor
the calling program such that is can alter SYSCOM. The RESTRICT service restores the upper
limit register to its previous value.

Assembly Language Call

PROVIDE:

RESTRICT:

BLU
DATA

$FROGS
8

$fr6gs

FORTRAN Call
CALL FROGS (8)

CALL FROGS (9)

4-12.5 Change Limits Service

A program may alter its restricted status by the following call:

TME
TMA
BLU
DATA

NEWLO
NEWHI
$FROGS
12

Upon return from the service, the program limit registers are set to NEWLO and NEWHI
respectively, and E and A contain the old values of the limits. If the new limits include part of
the operating system, the program will be executed as a privileged program until the limits are
again changed such that they no longer include any part of the system.

Table 4-4. Summary of FROGS Call

Value of n

Function

Initiate program.

Connect to External Interrupt

Enable External Interrupt

Disable External Interrupt

Release program connected to External Interrupt

4-14

Revision C
November 1975

Table 4-4. Summary of FROGS Call (Cont'd. )

Value of n

7
8
9
10

FuncHon

Place program on timer schedule for periodic
initial-ion.

Remove program from timer schedule.

Provide write -access to SYSCOM.

Restrict write -access to SYSCOM.

Initiate program at specified time.

Suspend program execution for specified period.

Change limits of restricted program.

4-13

ASSIGN SERVICE

The ASSIGN service provides dynamic I/O unit assignments for both foreground and
background programs. It modifies the calling program's own File/Device Control Block area
(Assign Table). The service is utilized with the following calling sequence for regular disc tiles:

TOI LFN

TMD FILENAM

BLU $ASSIGN

The following sequence is used for physical devices:

LFN

TOI
TZE
TOA

BLU
BON

PDN

$ASSIGN

ERROR (PDN is not in system)

The following sequence Is used for dynamic file creation of spooling files in spooled
systems only:

TOI
TMA

TME

BLU
BON

LFN
SDN

(spooled device PDN in bits 23-18, file size In sectors
or zero in bits 17-0) ( See text below)
=' 60000000 ( for spooled fi le create/return to user on error) or
=' 70000000 (for spooled file create/abort on error) or
='40000000 (for regular file create/return to user on error) or
= ' 50000000 (for regular file create/abort on error)
$ASSIGN
ERROR (PDN Is not spooled PDN in system)

4-15

Revision C
November 1975

where LFN is a valid Logical File Number {'77> LFN > 0); FILENAM is a 6 character
ASCII file name; PDN is a valid Physical Device Number (76 > PDN > 0); and SON is a valid
DN that is also a spooled device. (Physical device configured as terminal in spooled systems.)

10'

a) the LFN is invalid

b) the PDN is invalid

c) the SDN is invalid (spooled file create.)

If the specified logical file is open, the ASSIGN service will close/deallocate it
before making the assignment. An ABORT will result if the Assign Table is full or the Assign-
ment = is made.

The spool mode of the Assign service is used for making assignments to spool output
files. It is available only in spooled configurations of DMS and an abort will result if its use
is attempted in unspooled systems.

The file will be dynamically created by the system using ascending ASCII numbers
for file names. The file and its name are not actually generated until the file is initially
opened. If the spool mode is selected, the file will automatically be spooled out to the
device and deleted when output is complete. A second write operation to a spool file im-
mediately following a write which returned EOT status to the user will be considered to be
spool file overflow. From this point on, write requests to this spool file will be treated as
null requests. An operator message will be output at the time the overflow occurs. When the
file Is closed and automatically spooled out, an overflow message will be output following
the file. If the regular dynamic file create is used, the file Is dynamically named and created,
but is not spooled or deleted. The assigned file name may be referenced by the $SFUNC service
(mode 5). The file size field may be zero if the default size is desired. Otherwise, a size
as specified in sectors is placed here. If the size specified is not an exact multiple of the
blocked file blocking factor, it will automatically be rounded up to the next exact multiple.

The following sequence is used to squeeze out unused entries from the File/Device
Control Block Area.

TNI 1

BLU $ASSIGN

The squeeze call is used to remove all assignments for Logical Files which are
closed. In order to reuse these logical files after a squeeze, they must be re-assigned.

4-14 DYNAMIC CORE MANAGER ( DCM)

The Dynamic Core Manager provides dynamic core allocati or/deal location services.
These are accessible from both foreground and background with one exception: a background
program will not be allocated a memory block so large that the background program must be
checkpolnted to permit allocation of the block, but instead will be returned a memory space
not available" condition. This problem may be remedied by modifying the size of background
with an "MB" operator communications command.

The Dynamic Core Manager may be called via the following calling sequence:

TME

TMK

BLU

$DCM

DATA

where pi, p2 contain parameter(s) that are defined uniquely for each function; n
specifies the particular function as follows.

4-16

November 1975

Value of n

Function

3
4

Allocate a core block. The size in words Is
specified by pi. p2 contains a 24-bit identification
value so that the calling program can locate the
core block at a later time. (See following function).
Upon return, register K contains the memory location,
of the allocated core block. Error conditions are indi-
cated by

K=:_l insufficient memory available
=-2 ID already exists (core is not allocated)
=-3 insufficient memory exists to ever honor
the request.

Find core block. p2 contains the identification
parameter used when the core block was allocated.
Upon return, register K contains the memory location
of the specified core block.

Release Core Block. p2 contains the indentification
parameter of the core block to be released.

Release all core blocks. All core blocks allocated to
the given program are automatically released. This
function is always called by the Executive EXIT logic
when a program terminates.

Allocated 4-word cell. Returns in register K the loca-
tion of a special 4-word cell from the available cell
pool. These are used primarily by special system pro'
grams to pass spooled file information.

Release 4-word cell. p2 contains the location of a
4-word cell to be returned to the available pool.

Note that in order to access dynamic core blocks allocated by DCM, the calling program
must be operating in the privileged mode and care must be taken so as not to destroy
other programs in memory.

4-15

FIND PACK SERVICE

A service is provided to allow the calling program to locate the disc number
on which a specific pack is mounted. This is called via the following call:

TOI address of 120 word scratch buffer or zero

TOA pack number being located

BLU SFPACK

The disc drive numner on which the pack is mounted is returned in register
A. If the I register is zero when called, then the 120 word buffer will be allocated from
the Dynamic Core Manager.

If the specified pack is not currently mounted, then the operator will be
asked to mount it. When mounted, the disc number will be returned as above.

4-17

tevision C
sicvember 1975

^-16 UNTRAP SERVICE

UNTRAP provides the ability to have background processors read cards containing
f^S in column one from the assigned job stream device without having control taken av/ay by
lob Control.

Whenever a record is requested by a processor from job stream that has a dollar
ign in column 1, IOCS will set the system TRAP flag end return END-OF-FILE status to the
:alling program. In addition, the record containing the dollar sign will be oaded into the
jser' s buffer. If the calling program wishes to continue reading from this fi e Without havmg
:ontrol removed by Job Control, it must clear the TRAP flag by making a call to UNTRAP. Ad-
ditional records may then be read.

UNTRAP will not clear the TRAP flag if the record just read was either $JOB or

5EOJ.

Assembly Language Call FORTRAN CALL

BLU $UNTRAP CALL UNTRAP

4-17 SYSTEM RESTRICTED SERVICES

These services provide any background or foreground program the ability to perfrom
restricted system functions. The only requirement is that the programs must supp'y'''ie service
password in the D register when the service is called. The password consists of 6 ANSCII
characters, and is denoted in the following paragraphs by "KEY".

4-17. 1 File Creation

this service provides the ability to create a disc file of any size. The create service is
called via the following sequence:

TO I address of 336 word scratch buffer or zero

TLO PAR LIST

TMD "KEY"

BLU SSYSTER

DATA 1

PARLIST DATA pack ^ (on return contains disc number of pack)

DATA file size (words)

DATA 2 word ASCII file name

DATA 2 word ASCII file password or zeros

DATA file type (bits 23-16), memory requirement (bit 15-0)

DATA file protect bits (bits 18-16), absolute starting address (bits 15-0)

DATA absolute address for start of space allocation

Bit 18 set for read protection.
Bit 17 set for write protection.
Bit 16 set for delete protection.

If any of these bits are absent in accounting systems, then the corresponding accesses
are provided for other users on this file.

4-18

November 1975

The file type specification is defined as follows:

set for blocked file

set for spool file

set for core directory entry

set for permanent file

is the file type ('01 thru '11), see Table 3-1, FILE TYPES

If the content of the I register is zero when the call is made, a 336 word buffer is
dynamically allocated by the system for use by the create service, and the condition register .s
set to indicate whether the request was honored, and if not, why it was not. The condition
register is set as follows:

C = Positive -File name already used.

Q = Zero -Request honored. File was created.

C = Negative -Insufficient space on pack for file.

C = Overflow -Insufficient core available for 336 word buffer.

Bit 23

Bit 22

Bit 21

Bit 20

Bits 19-

-16

4-18A

Revision C
November 1975

The calling program can check the C register to determine what change or correctitjns
^are required to create the file.

If the content of I is non-zero when the call is made, any error condition (Positive,
Negative, or Overflow) will cause the calling program to be aborted.

If the requested pack is not mounted, an operator message is output and the pack must
be mounted prior to program continuation.

If it is desired to allocate the file at a particular sector number on disc, this value should
be put into the absolute start for space allocation parameter and the pack number must be negated.

If, in the case of a blocked file creation request, the file size specified is not an exact
multiple of the blocked file blocking factor, it will automatically be rounded up to the next
exact multiple.

4-17.2 File Deletion

This service provides the ability to delete any disc file providing the password is known.
The delete service is called with the following sequence.

TO I address of 336 word scratch buffer or zero

TMD "KEY"

TLO PARLIST

BLU $SYS

DATA 2

PARLIST BLOK 2

,r DATA 2 word ASCII file name

DATA 2 word ASCII file password

The returns from this service function In the same manner as those of the create service,
i. e. , if the content of I is non-zero when the call is made and an error occurs, the calling pro-
gram is aborted; if the content of I Is zero the C register is set as follows:

C = Positive -File was not present.

C = Overflow -Insufficient core for scratch buffer.

C = Zero -Request honored. File deleted.

4-17.3 Absolute Sector Read

This service provides the ability to read data from any disc location. Input to the service
is based on an absolute disc sector number (0-n, where n is number of sectors on disc) and word
count. Absolute Read is called via the following sequence.

PARLIST

TO I

address of buffer to rea

TLO

PARLIST

TMD

"KEY"

BLU

$SYS

DATA

disc number

DATA

absolute sector number

DATA

word count

4-19

4-17.4

Rename Fiie

This service permits to changing the name or type of any disc file. The
service is called as follows..

TO I address of 336 word scratch buffer or zero

TMD "KEY"

TLO PARLIST

BLU *SYS

DATA 4

PARLIST DATA 2 word old file name

DATA 2 word file password k ornN

DATA new type/memory requirement or zero (TYPE/MtM RE:U)

DATA new protectiorv^absolute start value or zero (PROTtLI/ABb blAKi;

DATA 2 word new file name or zero (NEW NAME)

DATA 2 word new file password or zero (NEW PASSWORD)

If the TYPE/MEM REG word is non-zero, its contents replace the corresponding
data in the Master Disc Directory (MDD) entry. If it is zero, the data is left unchanged.

If the PROTECT/ABS START word is non-zero, the protection bits in bits
18-16 replace those in the MDD entry and the contents of bits 15-0 replace the current
value of ABS START in the directory. In order to change the file to complete access
(bits 18-16 are zero) bit 19 of this word may be set to produce a non-zero value and
hense set the corresponding information. The contents of bits 19-16 are ignored in non-
accounting versions. See Figure 4-1.

Figure 4-1
Changing Protection with Rename Service

PROTECT/ABS START

If Non-zero, this becomes new
Absolute Program Start Value and
bits 18-16 replace bits 22-20 in word
3 of MDD entry (See Appendix A)

If set, causes delete access to be
prohibited

If set, causes write access to be
prohibited

If set, causes read access to be
prohibited

Should be set to cause contents of
bits 18-16 to replace those in MDD
entry, word 3 bits 22-20, Normally
used when public access is desired
(Bits 18-16 = 0).

4-20

If the NEW NAME words are non-zero, then they will become the new file
name. Otherwise the name will remain unchanged.

If the contents^ of both words of NEW PASSWD are zero, the old password
will be left unchanged. If however, they are non-zero, then the first 4 AN5CII
characters of these two words will become the new password. The password may thus be
changed to zero by making both words zero except for some non-zero value in bits 15-0
of the second word of NEW PASSWD.

The return from this service function in the same manner as the create service.
The condition codes are;

C = Overflow - Insufficient core available for scratch buffer.

C = Zero -Request honored - File renamed.

4-17.5 Special Assign

This service is used by certain system programs instead of Dynamic Assign to
change assignment for LFN 77 (program file). This is not a user service and is listed for
reference only. The calling sequence is as follows.

TLO

PARLIST

TMD

"KEY"

BLU

^SYS

DATA

PARLIST DATA 2 word ASCII file name to be assigned

The specified file name is assigned to the special program file LFN '77. This
allows reference to the file via LFN 77.

4-17.6 Background Load Request

This service provides the linkage to the system loader to load background
processors. It is called as follows.

TLO PARLIST

TMD "KEY"

BLU $SYS

DATA 6

PARLIST DATA 2 word ASCII program name

The specified program name is loaded into background and executed. The
service may be called only by background programs.

4-17.7 Write Absolute Sector

This service is the companion of Absolute Read by allowing data to be
written at any specified disc sector. The service is called as follows.

TOI buffer address of data to be written

TMD "KEY"

4-21

Revision C
November 1975

TLO PARLIST

BLU $SYS

DATA 7

PARLIST DATA disc number

DATA absolute secl-or number

DATA word-count

If the specified word-count is zero, a write end-of-file operation is performed.
Caution should be observed with this service, since it allows a program to write over an^
sector of_any disc, provided the service "KEY" is supplied.

4 - 1 7. 8 Se arch Master Disc Directory

This service is a orogram to test if a given file name/password is present in
the system. It is called as follows.

TLO PARLIST

TMD "KEY"

BLU $SYS

DATA 8

PARLIST RDAT 2 (0) (changed by system to non-zero)

DATA 2 word ASCII file name

DATA 2 word ASCII file password

BLOK 2 (words for temporary usage by service)

The specified file name and password are located ( if present) in the Master
Disc Director/. If the entry is present, the J register returns the address of the directory
entry which vili have been placed in the calling program' s PSA. The condition register
reflects the results of the operation:

C = Positive
C = Negative

-File name found and password is OK.
-File name/password not found in directory.

Due to the arrangement of the PSA, subsequent system service calls may overwrite
the contents of the MDD entry causing erroneous infomnation to be utilized.

4-17.9

Trigger lOEXEC

This service permits programs to trigger the I/O EXEC wait flag, causing the
I/O Executive to scan all terminals in order to perform required actions. This is needed
only by special foreground interactive processors and it should not be necessary to use this
in any user program. The service is called as follows:

TMD "KEY"
BLU SSYS

DATA 9

4-17. 10

In an unspooled system, this call has no effect.
Place File on Spool -In Queue

This service permits any program to place a file on the background spool
input queue. It is available only in spooled versions of DMS. The file to be placed on
the queue must not have a password, and must consist of symbolic images representing a
background job. The first image should be a valid $JOB (see Section VI) or the job will
be ignored. The service is called as follows:

4-22

Revision C
November 1975

TMD
TLO
BLU
DATA

"KEY"
PARLIST
$SYS
10

PARLIST

2 word ASCII file name
Priority in queue (1 -254)

An abort will result" if fhe priority is not valid. In an unspooled system, this call has no effect.

DATA
DATA

4-17. n Place File on Spool -Out Queue

spooled
The file
suitable
when th

This service permits proqrams to place a disc file name on the spool -out queue for any
or terminal device in spooled versions of DMS. It is non-existant in unspooled systems,
to be placed on the queue must have no password and must consist of symbolic images
for the destination device. If the file is typed as a spool file, then it will be deleted
e output operation has been completed. The service is called as follows:

TMD "KEY'^

TLO PARLiST

BLU $SYS

DATA 1 1

PARLIST DATA 2 word ASCII file name

DATA priority in queue (1 -254)

DATA device number to be spooled to

If the specified device is not a spooled or terminal device capable of output, the request
is ignored. In an unspooled system, this call has no effect.

4-17. 12 Overlay Load

This service provides the Overlay Cataloner an entry in the system to force a load of
overlay segments. Its use Is not intended for regular user programs.

4-17. 13 Execute User Routine on Interval Timeout

This service permits a sophisticated usage of the 120 Hz clock in virtually any situation
where some action after an elapsed timer interval Is desired. Execution of the user routine is
based on the following conditionals; (1) The timer Interval specified ^]5'if V?f'^l°? u/Ad no=n
PROGRAM STATUS WORD . AND. CONDITIONAL WORD 1 .XOR, CONDITION WORD2=0.
The calling sequence is:

TMD "KEY"

TLO PARLIST

BLU SSYS

DATA 1 3

PARLIST DAC ADDRESS OF USER ROUTINE

DATA CONTROL WORD (SEE BELOW)

DATA TIMER INTERVAL IN 120 Hz COUNTS

DATA CONDITIONAL WORD 1

DATA CONDITIONAL WORD 2

4-23

Revision B
March, 1975

If f-he control word is any positive value, conditions ore tested for execution periodical E
(as in the case of a scheduled program); if negative the special entry in the schedule tables for
this service is removed upon interval timeout whether execution conditions are satisfied or not.
The branch to the user routine is at dock interrupt level, and is a BSL. The user routine need
not save registers and must not exit via a BRL*. If the program is restricted, use must be made of
the service described in 4-12. 5 as necessary to prevent a branch at interrupt level to an address
within the limit register bounds.

4-17. 14 Remove Execute Routine Entry
be done:

To remove an entry in the scheduler table made by the above call, the following must

TMD

"KEY"

TLO

PARLIST

BLU

$SYS

DATA

PARLIST . . .

The parameters in PARLIST must have exactly the same values as when the entry described
in 4-17, 13was made. This permits as many entries per program as desired provided no two are
identical.

All entries associated with a given program are removed from system tables on an exit o|

abort.
EXAMPLES:

Suppose program A initiates some activity on an external piece of hardware, which in
turn triggers an interrupt to initiate program B to signal completion of the activity. Program A
might set a flag, do a BLU $WAIT and program B might reset the flag and just exit, at which
point program A would continue execution. To prevent a hangup if the hardware fails to respond.
Program A might use the following call to $SYS:

PARLIST

TMD

"KEY"

TLO

PARLIST

BLU

$SYS

DATA

DAC

ERADR

DATA

-1

DATA

120

'20

WFLAG

'20

WFLAG

If after one second, program A is still waiting on a flag, release address is WFLAG
(only bits 22 and 15-0 in the program status word are queried in this example). A BSL would
be made to ERADR, and the entry would be removed from the table. If the hardware responds
normally, and program B is initiated before one second elapses, program A could remove the
entry it made as it resumes execution.

4-24

Revision C
November 1975

CPARi ^°"J^°"^P^^' a program could make a permanent enfry in the scheduler table,
jmKLlbl + I) - +, and in effect have its own clock interrupt service routine; i. e. , a branch
to the user --oufine periodically. Conditional words 1 and 2 would both be set to zero to give
an unconditional branch condition.

4-] 7. 15 Special Delete

programs/'''' ^^'^'^^ '' ""'^"^ ^^ ''^''^°'" '^'^^'^ Programs. Its use is not intended for regular user

4-17, 16 Special Absolute Sector Read

This service is identical to the Absolute Sector Read (4-17. 3) except that a disc I/O
error will not cause the ca Img program to be aborted. If a disc I/O error occurs bit 20 of the
A register will be set and the actual word count transferred is returned in bits 0-15 of the A
register. The Special Absolute Sector Read is called via the following sequence

PAR LIST

4-17. 17 Special Absolute Sector Write

TOI

address of buffer to read

TLO

PAR LIST

TMD

"KEY"

BLU

$SYS

DATA

disc number

DATA

absolute sector number

DATA

word count

into

This service is identical to the Write Absolute Sector (4-17. 7) except that a disc I/O
error will not cause the calling program to be aborted. If a disc I/O error occurs, bit 20 of
register A will be set and the actual word count transferred is returned in bits 0-15 of the A
register. The Special Absolute Sector Write is called via the following sequence:

PARLIST

4-18 EXECUTIVE TRAPS

TOI

address of buffer to be written

TLO

PARLIST

TMD

"KEY"

BLU

^SYS

DATA

disc number

DATA

absolute sector number

DATA

word count

The executive trap routines are system modules of the resident portion of DMS. The
standard interrupt assignments for executive traps are defined in Table 4-5.

4-25

Revision C
November

1975

Table 4-5

. ExecuHve Traps

nkage Address (Octal )

Group, Level

Function

0,0

Power iail

0,1

Power Restore

0,2

Memory Protect

0,3

Instruction Trap

0,4

Stall Alarm

0,5

Interval Timer

0,6

SAU Trap

0,7

Address Trap

4-18. 1 Power Foil/Power Restore

When power fails, the power fail/restore routines saves registers and halt the machine.
When power is restored the message "Power Fail " is output to the operator communications device
and the machine again halted. Upon restart, the DMS system is rebooted from the disc.

4-18.2 Memory Protect /Instruction T rap

When the memory protect key switch is enabled, the DMS system has two modes of
operation. The non-resident services (e.g., ACRONIM, Job Control and File Manager) operate
in an unrestricted mode, that is, these services have access to any location in memory. Other
non-resident services or background programs operate in the Restrict/Unprivileged mode, i.e.,
the programs may not reference any locations below the first location of the program nor above
the highest location. Programs operating in the Restrict/Unprivileged mode are prevented from
executing certain instructions as defined in the Computer Systems Reference Manual.

en a

of 04.

memory protect violation occurs, the abort service is called with an abort codt.

When a instruction trap occurs, the abort service is called with an abort code of 03.

4-18.3 Stall Alarm

When a stall alarm violation occurs, the abort service is called with an abort code of 5.

4-18.4 SA U Overflow/Underflow Trap

The SAU Trap routine processes overflow/underflow conditions as described in Table 4-^,
4-18.5 Address Trap

The address trcp interrupt is triggered whenever the preset address is referenced in any
manner (including ABC channel transfers). If a program is active when the interrupt occurs, the
program is suspended and message giving the trapped address, program name, and the contents of
the registers is output on the operator communications device. If there Is no currently active
program when the interrupt occurs the program name in the output message is "NONE", and no
action other than the message Is taken by the system.

4-18.6 Interval Timer

The Interval Timer option (T-register) is required by accounting versions of DMS to
compute program execution CPU time. In non -accounting systems, the timer is not used and
thus is available to user programs.

4-26

Revision B
March, 1975

Table 4-6. SAU Trap Control

Error

Meaning

Result

Flag*

SAU 01

Square Root of a negative number

X=0.

SAU 02

Overflow during fix

A-F. S. P.

or F.S.N.**

SAU 03

Division by zero

X-F. S. P.

SAU 04

Arithmetic Underflow

X-0.0

SAU 05

Arithmetic Overflow

X-F.S. P.

or F.S.N.

SAU 00

Unrecognized SAU Trap

X-0.0

Notes:

1. F. S. P. denotes full scale positive value {X--'27777777 , '27777577 or
A= '27777777),

2. F. S. N. denotes full scale negative value (X= '40000000, '00000577 or
A= '40000001).

3. When the specifies result Is "F. S. P" or "F. S. N", the value selected
will hove the same sign as the result would have had, had there been no
overflow.

4. SAU 00 is returned for any SAU traps that do not fall Into the above
catagories.

*Flag indicates the cataloger "TYPE" flag that is used to determine action following
the error.

TYPE SPECIFICATION

Flog

Abort on error

No abort on error

Message on error

No message on error

OA
UA

NOA
NUA

OM
UM

NOM

NUM

^'Because of the asynchronous nature of the SAU, this SAU trap normally occurs one
instruction after the error causing Instruction (FXA). Thus, if an error Is possible during
the execution of an FXA, care should be taken so that the A register is not accessed
before the trap routine is able to adjust the result value. The standard FORTRAN Support
libraries already do this.

4-27

SECTION V
LOGICAL FILES AND PHYSICAL DEVICES

5-1 GENERAL

A logical file is a series of data records transmined to or from a specified
physical device. A logical file number is a number (0-n) used by a program to reference
a particular input or output file. A physical device number is a number (0-n) dedicated
to a particular device or a named disc file.

In DMS, physical device numbers are established by the position a device
handler's name in the peripheral device coordination table. By use of the Job Control
statement $ASSIGN, a logical file number may be assigned to a particular device. A
given logical file number may be assigned to only one physical device at a time. However,
multiple logical file numbers may be assigned to a given physical device at the same ^
time. By assigning a logical file number to physical device 0, the operator may nullify
all operations to that logical file, v/hich might be used to suppress all output to that file,
for example.

The peripheral device coordination table is a resident table. Logical file
assignments associated with a given program are contained within the program service
area's file/device control table and resident only when that program is resident. There
is only one program service area associated with background, common to Job Control and
all background programs, since only one background program can be active at a given
time. The background service area remains resident at all times.

Disc files are equivalent to physical devices. Disc files however, are
referenced by name instead of numbers, e.g., ^ASSIGN 10=SNOOPY. A physical device
control block contains only two words of information. A disc file control block contains
eight words including the file name, the first and last sector address, the current record
address, the current End-of-File address, and the disc file protection status. An EOF
within a disc file is functionally equivalent to an EOF mark on magnetic tape.

If a disc file is defined as "BLOCKED" when created, the disc file handler
will automatically perform record blocking and symbolic data compression.

For consistency between background processors and related system service
programs, certain logical file numbers are reserved. These logical file numbers (LFN)
are defined in Table 5-1.

For convenience and consistency between various systems, a suggested
standard table of physical device numbers (PDN) is given In Table 5-2.

5-2 INPUT/OUTPUT FUNCTIONS

Input/Output as discussed in Section IV, employes a logical file number and
function code in requesting I/O operations. The following paragraphs define valid j/O
function codes for each standard peripheral device. Table 5-3 provides a condensed list
of I/O function codes and their relation to standard devices.

5-1

Revision B
March, 1975

5-2. 1

Table 5-1
Standard Logical File Numbers & Default Background Assignments

LFN (Octal)

Definition

Default Assignment

Job Stream

device 07

Operator Communications

device 01*

Binary Input

device 04

Binary Output

file LR

List Output

device 06

Symbolic Input

device 77 (Job stream)

Symbolic Output

file Wl

Link Library File

file LL

Link Ready File

file LR

Link Go File

file GO

* Not Reas

signable

Table 5-2
Standard Physical Device Numbers

PDN (Octal)

Device

01
04
05
06
07
10
11
12
20
21
22

Console Teletypewriter
High Speed Tape Reader
High Speed Tape Punch
Line Printer
Card Reader
Card Punch
Magnetic Tape '^l
Magnetic Tape "2
TTY #0 (Console)
Remote TTY or CRT *\
Remote TTY or CRT #2

Common Device Function Codes

The two status checking function codes (00 and ^77) provide flexibility in the
processing of I/O calls.

If Function code 00 is specified in the call and the device is busy, the
calling program is placed in a waiting state until the current I/O operation is completed
and the ready status is set. Control is then returned to the calling program with the C
register set not negative. This is the regular status check and is normally done after all
I/O operations to guarentee completion.

If function code ^77 is specified in the call and the device is busy, control
is returned immediately to the calling program with the C register set to "negative", which
is designed as a special purpose "busy check".

5-2

Table 5-3. I/O Function Codes

Revision B
March, 1975

ACTION CAUSED BY FUNCTION CODE

OPENS ASSIGNED FILE

CLOSES ASSIGNED FILE

Sefs CRA CFA

Record

Advances to EOf
and SBti CFA ond
CRA

Soh CRA CfiA
- WC/WPS

Repoi<lioni la
Record of Cur
Fil«

AdvoncAs to EOF
ond Seh CFA, CRA
and EOF*

BQckspocei t

"RPF TR"
Hold Meitoge

"6SF TR"
Mold h^«iSoge

"BSR TR"
Hold Menage

Set Current

ftacord

Addreis

Seek C^(
Htcatd

Sat Curreni
File Address

Sets CRA CRA
' WC/WPS

Advances to End
of Record

Sen CRA S
CFA J9

Rewinds Tronsport
ond Sett CRA,
Cf A ond EOF*

Sen CRA -
Specified Secro
Nu.Tibet

Poiiiions Tope ro
Sepcitied Record'
wirhin File

Sots CFA CRA

DEALLOCATES FILES OR DEVICE

Open File ond Open File a

-I Stotus Set Options

CRA - Current Record Address
CFA - Current File Addreis
FSN - First Sector Number

LSN - Loit Sector Nvmber
WC - Word Count
WPS - Wordi Per Sector

MRS - Htxf Relal

ve Sector Number

I I -

85R - Bockspoce Record
BSF - Bocl(>poee File
RPF - R eposition File

IXn Aborr

5-3

Revision A
May, 1974

In either case, the A register contains the following information.
A /jq,= - Device not busy.

A «o= 1 -Word count not complete.

A «,= 1 - End-of-File detected.

A, 9"! - File Open.

A,c~A^ = Number of words read on input.

Table 5-4. Standard Disc Files

File Name

Definition

LR
Wl
W2
GO

Link Library File (Blocked)
Link Ready File (Blocked)
Work One File (Blocked)
Work Two File (Not Blocked)
Link Go File (Not Blocked)

5-2.2

Disc

The DMS disc handler processes three types of disc access requests:
absolute read/write, standard I/O non-blocked-file requests, and standard I/O blocked-
file requests.

Absolute read/write requests are initiated by system routines and honored
without restraint, bypassing normal IOCS file control logic.

Blocked and non-blocked IOCS requests are distinguished by the handler
from information obtained from the master file directory when the file is opened.

A blocked data record consists of a one -word record gap followed by
n-words of data. Each record gap contains a 12-bit backward and 12-bit forward word
count. Blocked records are packed in a dynamic blocking buffer until it is filled.
Buffer size is specified at system generation to be one or more sectors. Blocked records
may spill from block to block, but may not be longer than 4096 words, in compressed
form.

Symbolic data is compressed by converting all consecutive blanks into a
one-byte blank count.

Each block contains two pointers. Word-0 contains the record number and
block address pointer of the first record in the block, and word-1 references the lost
record of the block. Word-0 of block-0 contains the sector number of last recorded
block. These pointers allow rapid random access of a blocked file.

5-4

Revision B
March, 1975

Status (00 and 77) ~ The registers are returned as follows:
Register A

A23-1 If file is busy.

A22 -- 1 If word count was not completed.

^^21 ^- 1 If EOF record was detected on read or advance.

A19 = 1 File open.

A16 = A21 = 1 If file extents were exceeded on an input, output, or

advance, or if the last recorded record of a blocked
file plus one was requested on input, output, advance
or set record address.

A15-0 = Number of words transferred.

• Register C -^ F (A)

• Register I contains the first sector number of the referenced file.

• Register J contains the last sector number of the referenced file.

• Register K contains the next relative sector number of the referenced file.

• Register E contains the current relative record address (0-n) of the specified
file. For non-blocked files (E) will be the same as (K).

Symbolic Read (01) - If the file extents or the last blocked record address
are exceeded, input is suppressed and status bits 21 and 16 are set; otherwise, the transfer
is performed. If blocked, the current compressed record is decompressed and transferred;
and any remaining buffer is filled with blanks. If an EOF record is detected, status bit
21 Is set.

Symbolic Write (02) - If the file extents will be exceeded by this transfer,
output is suppressed and status bit 16 is set; otherwise, the specified word count Is trans-
ferred to the current sector address of non-blocked files. For blocked files, the symbolic
data is compressed (one or more consecutive blanks are compressed to a one-byte blank
count) and blocked into a dynamic blocking buffer. When the buffer Is filled it is written
on disc.

Binary Read (03) - For non-blocked files, Binary Read is identical to
Symbolic Rea3] For blocked files the current binary record Is unblocked into the user
buffer.

Binary Write (04) - The specified data record is transferred to the dynamic
core block for blocked files and transferred directly to disc for non-blocked files.

Edit Write (05) - For non-blocked files function 05 is the same as binary
write (04). i-or blocked tiles, this function sets an edit flag allowing an over-write of the
current record. (NOTE: This function implies binary write and the same word count as
the record being edited must be used. )

Write EOF (06) - An EOF sector is written on non-blocked files and an
EOF record (zero word record) is written on blocked files.

Open File (07) - Verifies the existence of the referenced file name and sets
the open status (Bit liJ). For blocked files, not already open, a dynamic blocking buffer
is allocated. The initial open of any disc file initiates a rewind of that file. On the
initial open of the file, the password, if any, must be supplied left Justified in the E & A
registers.

Revision C
November 1975

On return from a successful open request, "E", will contofn the blocking sector
count (0 in unspooled systems) and "A" will contain the file type and memory requirement for
the file;

B23 set for blocked file

B22 set for spool file

B21 set for core directory entry

B20 set for permanent file

B19-16 file type ('01 -' 1 1 ) see Table 3-1

B15-0 program memory requirements (non-zero only for programs)

Close File (10) - For blocked files, the current block is written to disc If
it is not empty.

Reposition File (11) - Record pointers are set to the CFA, or "current file
address" (i.e., the record following the previously encountered EOF record), or to a
rewind state if no EOF was encountered. CFA is set by reading an end-of-flle, advancing
to an end-of-file, or the "set current file address" function (21).

Backspace File (12) - The current record address is set to the record address
of the previous hUF record, or to the rewind position if no EOF was encountered.

Advance File (13) - File pointers are advanced to the record following the
next EOF record (blocked tiles) or sector (non-blocked files).

Backspace Record (14) - For non-blocked files, the specified word count
(if supplied In the 1/01:011) is converted to a sector count (112 words/sector) and
subtracted from the current record address. Where no word count is specified, one sector
is assumed. For blocked files the current record pointers are moved back according to
the blocked record gap which contains a backward and forward word count.

Advance Record (15) ~ File pointers are moved forward in the same manner
as the backspace: In the non-blocked file, on EOF will not be detected by an advance
reocrd.

Rewind File (16) - Current record address and current file address pointers
are set to zero.

Set Curr ent Record Address (17) - The current record address specified as
parameter one of the user parameter list is^tored as the CRA of the file. For blocked
files this function is valid only for previously written files or for sequential write requests
beginning immediately following the last recorded record, i.e. (SETCRA ==0, write,
SETCRA =^1, write, etc. ) If the specified record is greater than the last recorded record,
the file Is left positioned to the end of recorded data and status bits 21 and 16 are set.

Seek Current R eco rd A ddres s (20) - Null.

Set Current File Address (21) - The current record address is saved as a
"Current File Address" Ti"."e7, start of a logical file). This function allows mu I tl -pass
processors such as the assembler to set CFA at the start of pass-one and Issue a "reposition
file" (11) for subsequent passes, precluding the requirement for a work file.

5h5

Revision C
November 1975 „

Close/Deal I ocat-e (22) - Causes the file to be closed (function 10), then
deallocated. In the case ot blocked files, the d/namic blocking buffer is deallocated to
release the core.

Special Open (23) - Identical to Open File 07 except that if the referenced
file is not there, control is returned v/ith (C)=overflow & negative instead of aborting.

5-2.3 Magnetic Tape

One or more tope controllers ore handled by a re-entrant mag tope handler, Eac;h
of these controllers may control one or more drives. A private service routine is used to interflace
with each drive.

The following is a list of valid ]/0 functions and their definitions for the mag tape
handler.

Status (00-77) - Register A contains the common status word. The following ad-
ditional status is returned:

• Bit 22 of register A Is set to Indicate that the previous ]/0 request was not com-
pleted as requested.

• Bit 16 of register A is set if software end-of-tape is detected. See function ZO tor
a definition of software end-of-tape.

• Register K contains the current file number of the specified transport, where the
file beginning at load point is file number zero. This file number is incremented
once for each end-of-file detected or written in the forward direction and decremented
once for each end-of-flle detected In the reverse direction.

• Register E contains the current record address, a relative record number (o-n) within
the current file. A negative value indicates that the tape was backspaced over an
end-of-flle and a valid record number is no longer available.

• Register I contains a pointer to a seven-word block containing additional statqs
information:

The contents of these 7 words are as follows:

0, 1 hardware status word at completion of previous I/O request

1,1 hardware expanded status word at completion of previous ]/0 request

2, 1 current hardware status word (status 00 only)

3, 1 current hardware expanded status v/ord (status 00 only)

4, 1 number of retries on last ]/0 request

5, 1 total number of retries since device was opened

6,1 net number of foreward requests processed since encountering hardware endr

of-tape marker. A negative value indicates an end-of-tape marker not yet;

encountered.

Notes- A value of -2 as hardware status or hardware expanded status indicates that the particular
status is not available due to hardware limitation or failures. Status 77 will not return current
hardware status.

Symbolic Read ( 01 )/Symbolic Write (02) - Internal symbolic data is assumed to be ANSCll,
3 C/V>/, and is transmitted to or from tape as 24-bIt binary. Conversion to or from BCD is
controlled via a tape-options table resident in the system or passed on via a special open
request. Symbolic conversion is always 3 cpw, right justified in 8-bit bytes. Seven track
tapes are converted to/from 6-bit BCD and nine track to/from 8-bit extended BCD. The
transport type is specified at system generation. See Section 6-2. 13, STAPEOP statement.
For a description of error handling, see function 20 (set Error Options).

5-6A. 1

Revision C

November 1975

Binary Read (03) - The specified number of words are requested from fhe appropria»-e transport.

Mode and densiTy are taken from a tape option table in the resident system or passed on via a

special open request. For a description of error handling, see function 20 ( Set Error Options).

Bi nary Write (0 4) - The specified no. of words are transferred to the appropriate transport. Mode
and density are taken from a tape option table in the resident system or passed on via a special
open request. For a description of error handling, see function 20 ( Set Error Options).

Erase (05) - Parameter two of the users parameter list specifies an erase repeat count (n) such that
(n) (3.5 inches) of tape are erased. After reaching software end-of-tape ( See function 20), a
maximum of one 3.5 inch erase will be perfomed per function call. If the repeat count is not
satisfied, WCNC status will be set and the word count returned on a status call will indicate the
number of erases performed.

PARLIST DATA ' XX05

DATA repeat count (n)

Write EOF (06 ) - An end-of-file record is written. The current file number is Incremented and
the current record address and current fi le address are set to zero.

Qpend Fi le ( 07 ) - An open bit is set in the user's device control block. The tape-options word
is copied from TFie system tables on the initial open.

Close File (10) - Null

R eposition File ( 11) - The tape is repositioned to the first record of the current file (end of the
previous End-of-File Record).

Backspace File (12) - The tape is positioned to the start of the previous End-of-File record. The
current file number is decremented, the current record address is set to -1 and the current
file address is set to zero.

A dvance File ( 13) - The tape is positioned to the end of the next End-of-File record. The file
number is incremented and the current record address and current file address are set to zero.

B ackspace Record ( 14) - The tape is positioned to the start of the previous record.

A dvance Record ( ]5) - The tape is positioned to the end of the next record.

Rewind ( 16) - The tape is repositioned to load point. The file number, current record address and
current file address are set to zero.

Set Current R ecord Address ( 17) - The tape is repositioned to the record number specified in the
parameter list. The first record of each file is record zero. If the specified record does not exist
in the current file, the tape is positioned at the beginning of the next file, the file number is
incremented and the current record address and current file address are set to zero.

PARLIST DATA ' XXU

DATA record number

Set Error Options (20) - The error options are set as specified. Any options not specified are
res et to the system def aults. The number of options specified is indicated by word two of the
parameter list. In other words, to change option word 4, the parameter list word 2 would be set to
4 and the first four option words must be specified. Option words 5-8 will be reset to the system
defaults in this case. The parameter list is of the form:

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Revision C
November 1975

PAR LIST DATA ' XX20

DATA N ( Number of options specified)

DAC OPTNLST (Address of option list)

OPTNLIST DATA WORD 1

DATA WORD 2
DATA WORD N

The Error Options are defined as follows:

Word 1 - Read Error Positioning/Hold Message

- 1 - position before faulty record a fter retry limit
is exceeded.

2 - position after faulty record after retry limit is
exceeded
If bit 23 set - position as specified and output operator hold message
repeat previous read operation if released
reset - position as specified and return to user program

Standard system defaults ore positioning before faulty record and outputting operator hold
message (1, bit 23 set).

Word 2 - Write Error Positioning/Hold Message

~ 1 - position before faulty record and any erase attempts, after
retry limit is exceeded
2 - position before faulty record but after any erase attempts
after retry limit is exceeded
- 4 - position after faulty record after retry limit is exceeded
If bit 23 set - position as specified and output operator hold message -repeat
previous v/rite operation If released
reset - position as specified and return to user program

Standard system defaults are positioning before faulty record (but after erases) and out-putting:
operator hold message (2, bit 23 set).

Word 3 - Number of Retries Allowed on Read Error.

This is the number of re-read attempts which will be allowed upon detection of

a read error. This number must be less than 256. The standard system default is ^5.

Word 4 - Number of Retries Allowed on Write Error.

This is the number of re-write attempts allowed at one spot on the tape upon
detection of a write error. This numbermust be less than 256. The standard system
defualt Is 2.

Word 5 - Number of Erase/Re-Writes Allowed on Write Error.
If the write retry limit is exceeded (word 4), 3.5 inches of tape will be erased and
the write attempts repeated on the new spot on tape. This word specifies the number
of erase/re-write attempts to be allowed and must be less than 256. The standard
system default is 3.

Word 6 - Software EOT locatior/Hold Message.

This word defines where the "software EOT" is located as well as the action taken
when it is reached. "Software EOT" is defined as the net number of forward tape
operations allowed after detecting hardware EOT. The number specified must be
less than 256. If bit 23 is set, an attempt to position past software EOT will output
an operator hold message. If the program is released the handler will assume a new

5-7

Revision C
November 1975

tape has been mounted and the operation will be performed If bit 23 is not ^^^^'/.^J^fPI^-^t'^"
will be performed and status bit 16(EOT) will be set. No hold message ,s output ,fbt 23 ,s not
Tet. The standard system default is not foward operations allowed = and output hold message
at EOT (0, bit 23 set).

Word 7 - Close/Deallocate Special Action.

This word defines any special action to be taken upon close/deallocate

(function 22).

- no special action

1 - rewind tope upon c lode/deal locate /, n ,

r^ 2 - output operator message "UNLOAD TAPE T#) upon close/deallocate.
This is only a message and does not suspend the program.
3 - rewind tape and output message
If bit 23 set - program will be suspended until tape drive is switched
off-line
reset - program does not wait for drive to go ott-line
The standard system default is no special action (0).

Word 8 - Software Write Protect.

- -allow writes to be processed normally nr .■

- 1 - oil write functions (02, 04 05 and 06) are treated as null functions.

If bit 23 set - output hold message "WP VIOLCATION" upon write

attempt - if released, the write operation will be performed
or ignored as specified

The standard system default is no special action (0).

Set Current File Ad dress (21) - This function causes the current record address to be saved as a
fa ke "start of f ile" so that a subsequent Reposition file will reposition the tape to this record
address. This pennits the assembler, for example, to assemble a string of programs without End-
of-File separators or an auxiliary work file for pass two.

Close/Dealloca te (22) - The tape drive is deallocated from the calling program. Any special
action previously requested with function 20 is perfonned.

Special Open (23) - The open bit is set in the user's device control block and if the call is of
^e long form th Fiecond parameter contains the tape options word to be used. 1 he form of this
word mSst be identical to that in the Default Tape Option Table given m Appendix A.

PARLIST DATA ' XX23

DATA tape options word

5-2.4 Teletype Ter minals

One or more teletypes are handled by a reentrant teletype handler. Each
teletype is interfaced by a private service routine, allowing local or long distance
communications via any standard hardware mterfoce.

Anyone of the teletypes may be specified at the operators terminal at system
qeneration. The operators terminal may be alternately specified at system-boot time
brseHing sense-switch one along with the desired terminal device number m control
switches 0-5, before activating the bootstrap.

5-8

Revision C
November 1975

The specified operators fermlnal funcHons as a normal remote terminal in
addition to being the Operator Communications console. The operator communications
service (OPCOM) is not accessable from any terminal other than the operators terminal.
The operator may relinquish operator communications to another terminal via the command:

/OT,n

where n is the desired terminal device number.

The reentrant teletype handler honors standard IOCS requests for all
teletypes, including the assigned operator's terminal. Additionally the following special
action keys are acknowledged from all terminals:

Control "X-OFF" Abort termina l job - applicable only in spooled systems,

the "X-OFF" key causes the I/O Executive to abort
the current terminal program, if any, and the message
"ABT. . " io be typed.

5-8A

Control "RUB-OUT'

Control "BELL'

'/"

It ^— II

Control "TAPE"

Control "TA-P€'

Note:

Control "FORM'
"Line-Feed"

Line Delete - If input is active, the "RUBOUT" key
is considered to be a line delete; in which case the
handler outputs a ".' " character followed by a
carriage-return and line-feed, then reinitiates the input
request, unless the input being cancelled was an OPCOM
request, in which case input is not reinitialized.

Terminal Activation - In spooled systems, an input request
bit is set causing the I/O Executive to initiate an
input request for the interactive terminal editor
(ACRONIM).

OPCOM Request - A "/" as character one of an input
record defines an operator communications statement,
and is ignored from all except the operator's terminal.
If an Input request is active at the operator's terminal,
a "/" causes the input parameters to be saved for
restart, and input to be Initiated into the opcom Input
buffer. This buffer is passed to OPCOM by the handler
upon detecting an end-of-record. The original input
is then reinitiated by the handler. If input is not
pending when an operator communications statement Is
Issued, it is passed to OPCOM and the handler reset
to an idle state.

Character Delete - Each ' "*" " causes the handlers
Input column pointer to be decremented. If decremented
to zero, a line delete is effected (i.e., a "I", carriage-
return, and line-feed).

Tape-On - The control key "TAPE" causes a tape
reader flag to be set so that subsequent Input requests
for the terminal will be accepted from the paper tape
reader.

Tape -Off - The control key "TA-P-E"' resets the tape
reader flag so that subsequent Input requests ore
accepted from the keyboard. Note that a properly
prepared input tape should be terminated by a "TA-P-E".
If not, the operator may type a "TA-P-E" during trailer,
because reader and keyboard data are ORed, Removing
the tape from the reader will also disable the reader.

"TAPE" and "TA-P-E" are not relevant for unmodified
teletype transmission over MODEMS, because tape
input is enabled by a manual switch.

Feed Tape - The control key "FORM" causes 6 inches
of tape to be punched as leader.

Start of Record - The 8-bit linefeed code ('212) is
defined as a binary start -of -record. Linefeeds are
Ignored for symbolic Input.

5-9

Revision A
May, 1974

"Carriage -Refurn" End of Record - The S-bif carriage return code ('215) is

defined as a binary end-of-record. For symbolic input,
carriage returns are ignored prior to the first input
character; afterwards it is an end-of-record code (seven
bit ASCII '015).

Control "EOT" Binary EOF - The 8-bit code '204 is defined as a binary

EOF for standard paper tape handlers, therefore the tele-
type handler honors this code as an input EOF.

Standard IOCS functions are listed below with a description of their meaning to the
teletype handler.

Status (00) - Normal status is returned in register A and register C is set as a function
of A.

Symbolic Read (01) - The user buffer is blanked and up to 72 characters of input are
accepted, terminated by a carriage return. A carriage return is defined as an end-of-record
code, so that a blank line is input if no characters precede the carriage return. Line feed
codes are ignored.

A line feed is issued as an input ready signal each time an input request is made.
A "$EOF" statement is defined as an EOF input record.

Symbolic Write (02) - A leading line feed followed by up to 72 characters (trailing
blanks are suppressed), and a carriage return are output. Cq is assumed to be a forms control
character and is not output. If Cq = "1 " a triple line feed precedes the output and if Cq = "0"
a double line feed precedes it.

Binary Read (03) - The tape mode is set and the tape reader enabled. Following the
start -of-record code ('212) 6-bit binary bytes are accepted and packed four per word until the
user's word count is complete or an end-of-record code ('215) is detected. The 8-bit code
('204) is detected as an end-of-file condition.

Binary Write (04) - A start -ot-record code ('212) is output, followed by the user's data
unpacked as four 6-bit bytes per word, until the user's word count is complete. The record is
terminated with an 8-bit end-of-record code ('215).

JJn&a mgtted Write (05) - The lower eight bits (7-0) of every word ore output with no
conversions. The bits 23-8 are ignored.

Write End -of -File (06) - The message "EOF. . " is output, preceded by a line feed and
followed by an EOT and carriage return. The EOT ('204) is a non -printing character, defined
as a binary EOF code.

Open (07) - An open flag is set, causing 6 inches of tape leader to be output before
the first record if the output is binary.

Close (10) - Null.

Reposition File (11) - The message "RPF, . " is printed and the user placed in wait
until the "TAPE" key is pressed by the operator.

Backspace File (12) - Null.

5-10

Revision C

November 1975

Advance File (13) - The message "ADF. . " is printed and the user placed in
a wait until the " lAft" key is pressed.

Backspace Record (14)- The message "BSR, . " is printed and the user placed
in a wait until the "TAPE" key is pressed.

Advance Record (15) - The message "ADR. . " is printed and the user placed
in a wait until the "lAPb" key is pressed.

Rewind (16) - Null.

Unformatted Read (17) - Data is input from the terminal and stored in bits 7-0 in
the user's bufter, with no data or format conversions. Bits 23-8 are set to zero.

Seek Current Record Address (20)- Null.
Set Current File Address (21)- Null.

program.

Close/Deallocate (22)- Closes and deallocates the device from the calling

Special Open (23)- Null,

5-2. 4A TI SIient-700 Terminals with Cassettes

One or more Si lent-700' s are handled by a re-entrant Silent-700 handler. Each
Silent-700 is interfaced by a private service routine, allowing local or long distance communis
cations via any standard hardware interface.

Note: Silent-700' s without cassettes (KSR models) should be regarded in all
respects as teletypes (see section 5-2.4). This section only pertains to ASR models with cassettes.

All functions using the keyboard printer of the Silent-700 are similar to those for
a teletype with the following differences:

Special Action Keys:

"RUB-OUT" is not used. To obtain a Line Delete either the "DEL" or the
"ESCAPE" key may be used.

"^- " is not used. To obtain a Character Delete the underscore key may be
used ( "US" or "_")• '

"Control TAPE", "Control NOT TAPE", and "Control FORM" are not used.
"Line Feed" is ignored on all input.

Standard IOCS functions are listed below with a description of their meaning to
the keyboarci/printer section of the Silent-700.

Status (00) - Normal status is returned in register A and register C is set as a
function of A.

Symbolic Read(OI) - The user buffer is blanked and a line-feed is issued to indi-
cate an input request is pending. A carriage return is used to terminate input.

5-10A. 1

Revision C
November 1975

A "5EOF" or a "Control EOT" is recognized as an End-of-File.

Symbolic Write (02) - Up to 80 characters from the user' s buffer are output
(trailing blanks are suppressed). The first character is the user's buffer is not printed but is
used as forms control:

"1" causes a triple line feed
"0" causes a double line feed
"+" causes no line feed.

all others cause a single line feed.

Binary R ead (0 3) - Null.

B inary Write (04) ~ Null

Unformatted Write (05) - The lov/er eight bits (0 thru 7) of each word are output
with no conversion, no line -feed or carriage return. This continues until the word count ,s
complete.

Note- Several characters are processed by the Silent-700 as commands. Because
of this, these characters will not be output for any Write function code. Instead a NUL character
(octal 000) will be output. These characters are:

DLE - octal 020

DC1 - octal 021

DC2 - octal 022

DC3 - octal 023

DC4 - octal 024

Write End-of-File (06) - The message "EOF. . " is output.
Open (07) --^Null
Close (10) - Null

Reposition File (1 V) - The message "RPF. . . " is output.
Backspace File ( 12) - The message "BSF. . " is output.
Advance File ( 13) - The message "ADF. . . " is output.
Backspace Record (J4) - The message "BSR. . " is output.
Advance Record ( ]5) - The message "ADR. . " is output.
Rewind ( 16) - Null

U nformatted Read ( 17) - Data is input from the terminal and stored in bits 7
thru of the user' s buffer ( 1 ^aracter per word). Input data is nol^ echoed to the terminal.
Bits 23 thru 8 are set to zero.

Seek Current Record Addr ess ( 2 0) - Null
Set Cu rrent File Address (21) - Null

Close/Deallocate (22) - Closes and deallocates the device from the calling program.

5-lOA. 2

Revision C
November 1975

All other function codes are null.

Cassette ]/0 - All cassette data is recorded in 86 character blocks. The Silent-
700 handler v^iil automaticcaly pock records into a block to avoid waste. Therefore, records
may be v/holly contained within blocks or they may be spread across 1 or more blocks. The
formats of records as processed by the handler are as follows:

Symbolic Records - Leading line feed, followed by the symbolic record without
translation, followed by a carriage return.

Binary Records - Leading line feed, followed by the binary record encoded at 4
characters per word. Each character consists of 6 bits from the binary word (most
significant bits first) padded by adding octal ' 40 to the 6 bit character. On a
binary read, this padding is removed. The record is tenninated by a carriage return.

End-of-File Record - An EOF record is a two character record consisting of an EOT
(octal ' 004) and a carriage return (octal' 015), On input an EOF record is any
record which begins with an EOT.

Standard IOCS functions are listed below with a description of their meaning to the
cassette section of the Silent - 700.

Status ( 00) - Normal status is returned in register A and register C is set as a function
of A.

Syrr.bolic Read (01) - Input is read from the cassette until a carriage return is received.
T he remainder of the user' s buffer is set to blanks. If the user' s buffer is too small,
trailing data is lost.

Sym bolic Write (02) - Data is written to the cassette from^ the user' s buffer. Trailing
blanks are suppressed. A carriage return is output to terminate the record.

Binary Input (03) - Data is transferred from the cassette to the user's buffer according
to the format discussed above. Input is temnlnated by a carriage return.

Binary Output (04) - Data Is transferred from the user's buffer to the cassette according
fo fhe fonnat discussed above. The record is terminated by a carriage return.

Unformatted Write (05) - The lower eight bits of each word In the user's buffer is
wr I Hen fo the cassette w ithout any conversion (see Note under Keyboard/Printer
Unformatted Write). Bits 23 thru 8 are ignored. A carriage return is not output,

Write End-of-File (06) - An EOF record (EOT, carriage return) is written to the
cassette.

Open (07) - Null

Close ( 10) - Any partially written cassette blocks are dumped to the cassette. This
also occurs whenever a physical tape movement Is required.

R eposition File (11) - A backspace file followed by an advance record is performed.

Backspace File (12) - Record are backspaced over until an EOF record is encountered.
A subsequent read will input the EOF record.

Advance File (13 ) - Records are advanced over until an EOF record has been skipped.

5-lOA. 3

Revision C
November 1975

B ackspace Record ( 14) - Characters are examined backwards until a carriage return
is read. The resultant position is immediately after the carriage return.

A dvance Record ( 15 ) - Characters are input and ignored until a carriage return has
been processed.

R ewind ( 16) - The cassette is rewound to its "clear leader". It will be "loaded" to its
Toad point upon any subsequent function request except 00-Status, 1 1-Reposition File,
12-Backspace File or 14-Backspace Record.

U nformatted Read ( 17) - Data is input from the cassette and stored without conversion ii
bits 7 thru of the user' s buffer. Bits 23 thru 8 are set to zero. Transfer continues untl
the user word count is complete. ,

S eek Current Record Address ( 20) - Null

S et Current File Address (21) - Null

Close/Deallocate (22) - Closes and deallocates the device from the calling program.

All other function codes are null.

Due to interactions between the keyboard and the cassettes and due to internal buffer! n
of cassette blocks, the following rules must be observed.

1. When using the Silent-700 as the operator communications device, the cassettes
should not be used.

2. The terminal "Control X-OFF" should not be used when cassettes are actually in us^
(motion).

3. The first operation on a cassette after inserting it into the Si lent-700, after
any manual positioning of the cassette or after a reboot should be a rewind.

4. The record control tape format switch must be in the CONTinous mode.

5-'0A. 4

Revision C
November 1975

5-2. 5 Paper Tape Reader

The following "is a list of valid I/O functions and their definitions for the
paper tape reader.

Symbolic Read (01) - Data is accepted on an interrupt basis (one character
per interrupt) until a carriage return character is detected. If a carriage return is
detected before the word count is complete, the user's buffer is filled with blanks. If the
word count is satisfied before receiving the carriage return, the trailing data within the
record is ignored. The data is converted to ANSCII and packed three characters per
word as it is received. If an up-arrow (f ) is detected during input, the record is
ignored and the input operation is reinitialized. A delete code {'o77) is ignored. Leading
line feed and carriage returns serve as record delimiters and are ignored.

Symbolic Write (02)- Invalid function code.

Binary Read (03 )- The binary tape format is four 6 -bit frames per word.
Each binary record is preceded by an 8-bit line feed ('212) and terminated by an 8-bit
carriage return ('215). Data is accepted on an interrupt basis (one character per
interrupt). After detection of a line feed, data is packed in the user's buffer, four
frames per word. On detection of a carriage return, input is terminated. If the user's
word count is satisfied before detecting a carriage return, the status word (B15-B0) will
indicate the actual number of words transferred and B22 is set.

Binary Write (04) - Invalid function code

Unformatted Read (05) - Eight-bit bytes are input on an interrupt basis
and stored, one byte per word into bits 7-0, without conversion until the specified word
count (byte count) Is satisfied.

Write EOF (06) - Invalid function code.

5-]]

O pen (07) - Null.

Reposition File (11)- Operator hold message "RPF TR" is tyPed- The
operator shouFg repos i t i on the ta pe to the end of the previous End-of-f.le record and
release.

Backspoce File (12)- Operator hold message "BSF TR'' is typed. The
operator shouFa repos i t i on the ta pe to the start of the previous End-of-f.le record and
release.

Advance F i le (13 )- Tape is advanced past the next End-of-File record.

B ackspace Record (14 )- Operator hold message "BSR TR" is typed.

Advance Record (1 5)- Tape is advanced past the next carriage return.

R ewind (16) - Null.

Set C urrent Record Address (17 )- Invalid function code.

Seek Current Record Address (2 0)- Invalid function code.

Set Current File Address (21 )- Invalid function code.

Close/Deallocate (22)- Null.

S>ecial Open (23)- Null.
5-2.6 Paper Tape Punch

The following is a list of the I/O functions and their definitions for the
paper tape punch.

Symboli c Read (01 )- Invalid function code.

'iymbolic Write (02)- The handler outputs three 8-bit frames for each word
of the user's Buf f er. A l^5Hn^ line feed ('212) and a trailing carriage return (215) are
generated by the handler. Data is unpacked and transferred on an interrupt bas.s unt.l
the word count is complete.

Binary Read jOS)- Invalid function code.

Binary Write (04)- The handler outputs four 6-bit frames for each word of
the user's buffer. AfTS^TTTine heed ('212) is punched as a start of record and a
carriage return ('215) as an End -of -Record.

Special Action (05)- Unformatted Write. The handler outputs one 8 -bit
frame for eacK word ( / -O) i n the user's buffer. Transfer continues until the word count
is satisfied. Start and End-of -Record codes are suppressed, permitting the user to generate
any type of formatted type.

Write EOF (06)- Punches End-of-File code (EOT = '204) as the start code,
followed by a" carriage rehTrn. This generates a zero word record with EOF as the
start-of-record.

5-12

Open File (07)- Punch power is turned on and 18 inches of leader (blank
tape) is generated.

Close File (10) - Punches End^f-File code (EOT = '204), generates 18
inches of trailer (blank tape), and turns off punch power.

Reposition File (11)- Invalid function code.

Backspace File (12)- Invalid function code.

Advance File (13)- Invalid function code.

Backspace Record (14)- Invalid function code.

Advance Record (15)- Invalid function code.

Rewind (16) - Null.

Set Current Record Address (17) - Invalid function code.

Seek Current Record Address (20 )- Invalid function code.

Set Current File Address (21 )- Invalid function code.

Close/Deallocate (22)- Closes the device as with function 10 above, if not
already done, and deallocates the device from the calling program.

Special Open (23)- Invalid function code.

5-2. 7 Card Reader

Card input is buffered and converted according to the IOCS input request.
Some special checks are made by the handler before allowing a transfer to the user
buffer.

A card image of "$26" in columns 1-3 is thrown away and the H026 code
conversion flag is set. A "$29" card sets the H029 flag. H029 is assumed as default.
A 9/8 multi -punch in column one is defined as an EOF record.

All other records are passed to IOCS and tested for "$" job control
statements. If they pass these tests, data Is passed to the user buffer according to the
following function requests.

Symbolic Read (01)- A single 80 column card Is converted from 026 or
029 code to Infernal AnSCiI, three characters per word, until the user's buffer is filled
(byte 81, and all other words greater than 27 (if any) will be blank).

Symbolic Write (02 )- Invalid function code.

Binary Read (03)- Consecutive cards are accepted and passed to the user's
buffer, until the specified word count is satisfied or until an End-of-Record card is
detected. Binary cards are formatted as follows:

5-13

• Column 1 -Reserved for a special action code: A 9/8 multi-punch
signifies an End-of-File record, and a 9/7 multi -punch Is a partial
code signifying that this card does not complete the binary record.

• Column 2 - blank.

• Columns 3 through 6 - Reserved for a user sequence number.
The handler ignores 2-6.

• Columns 7 through 80 - Contain 12-bit binary data allowing 37 data v^'ords
per card, at 2 columns per v/ord.

Binary Write (04)- Invalid function code.

Hollerith Read (05)- A single 80-column card is transferred to the user's
buffer, without conversion, and packed two columns per word.

Write EOF (06)- Invalid function code

Reposition File (11)- Operator hold message "RPF CR" is typed.

Backspace File (12)- Operator hold message "BSF CR" is typed.

Advance File (13 )- Cards are input until an End-of-File card (9/8 multi -
punch in column 1) Is detected.

Bac kspace Record (14)- Operator hold message "BSR CR" is typed.

Advance Record (15 )- Cards are input and ignored until a card not
containing a 9// multi -punch In column 1 Is detected.

Rewind (16) - Null.

Set Curr ent Record Address (17)- Null.

Seek Current Record Addre ss (20)- Null.

Set Current File Address (21 )- Null.

Close/Deallocate (22) - The device Is deallocated from the calling program.

Special Open (23)- Null.

5-2.8 Card Punch

card punch

The following Is a list of the I/O functions and their definitions for the

Symbolic R ead (01)- Invalid Function Code.

Symbolic Write (02)- Converts ANSCII to Hollerith core and punches 1
card. Conversion code is assumed to be H029 unless system option 23 is set, requesting
H026 conversion

5-14

Binary Read (03)- Invalid funcHon code.

Binary Write (04) - Punches one or more cards as a binary record. Column 1
of each card is reserved as a special acMon code. A 9/8 MulH-punch in column 1
indicates an End-of-File record (one card). A 9/7 multi-punch indicates a partial record.
Columns 2 through 6 are open for a sequence number (the handler does not generate a
sequence number).

Special Action (05)- Punches 80 columns, 2 columns per word, unformatted.

Write EOF (06)- A 9/8 multi -punch is punched in column 1.

Open (07)- The device is allocated to the calling program.

Close (10)- A blank card is punched.

Reposition File (11)- Invalid function code.

Backspace File (12)- Invalid function code.

Advance File (13)- Invalid function code.

Backspace Record (14)- Invalid function code.

Advance Record (15) -Invalid function code.

Rewind (16) - Null.

Set Current Record Address (17)- Invalid function code.

Seek Current Record Address (20,)- Invalid function code.

Set Current File Address (21)- Invalid function code.

program.

Close/Deallocate (22)- The device is closed and deallocated from the user's

Special Open (23)- Invalid function code.

5-2.9 Line Printer

line printer.

The following is a list of valid I/O functions and their definitions for the
Symbolic Read (01)- Invalid function code.

Symbolic Write (02 )- Data is assumed to be ANSCII, 3 C/W. The first

column IS assumed to be a carriage control character and the printer responds in the

manner defined in Table 5-5. Special characters "1", "0", " ", or "+ " in this position
are replaced by the appropriate control character as indicated in Table 5-5.

Binary Read (03)- Invalid function code.

Binary Write (04)- Invalid function code.

5-15

Special Action (05) - Invalid function code.

Wr ite EOF (06 )- The message "EOF.." is printed.

Re position File (11)- Invalid function code.

Backspace File (12)- Invalid function code.

Advance File (13)- Invalid function code.

Ba ckspace Reco rd (14)- Invalid function code.

Advance Record (15)- Invalid function code.

Re wind (1 6)- Null.

Se t Current Rec ord Addres s (17)- Invalid function code.

Se ek Cu r rent Record Address (20 )- Invalid function code.

Set Current File Address (21)- Invalid function code.

Cl ose/Dealloca te (22)- The device is deallocated from the calling program.

Special Open (23)- Invalid function code.

Table 5-5
Line Printer Carriage Control

Carriage Control

Character

Action

"Cg)" or " + "

line advance

"A" or " "

1 line advance

Accepted by-

"B' or "0"

2 line advance

all printers

"C"

3 line advance

"D"

4 line advance

■

Accepted only
by obsolete

"N"

14 line advance

printers

"O"

15 line advance

All spacing
is done
before

M pit

"Q"
"R"

Channel 1 (top of form)
Channel 2
Channel 3

Accepted by
-all printers

"S"

Channel 4

Accepted by

printing.

■ only some

-W"

Channel 8

printers

: (colon)

Causes columns 4-18 to
be output to the operator
as a Hold Message, upon
release, program executio
continues.

Other

1 line advance

-f

5-16

Revision A
May, 1974

5-2. 10 Real-Time Peripheral Equipment

The RTP Handler will handle the RTF I/O Expander and up to 30 RTF devices, each
containing up to 16 channels, for a total of 480 controlled channels. Each RTP "Device", or
set of 16 channels on a common controller, is assigned a particular DMS physical device num-
ber, and can be open to, at most, one program at a time. Thus, when a program opens a parti -
cular RTP device, it has sole control of the 16 channels on the device.

DMS physical device numbers are associated with RTP device numbers through a resident
DMS table which is defined at system generation (see Paragraph 12-3. 17). A second system
table contains a bit for each channel on each RTP device which is used to determine whether
the particular channel is interrupt or non-interrupt oriented.

I/O is performed to the RTP devices through standard I/O calling sequences utilizing
function codes 01 through 04. For each call, two buffers are transferred to the handler.

As can be noted, there are two distinct methods of programming RTP equipment:
Sequential and Random. In sequential operation the I/O transfer is begun at a particular card
or channel on the RTP equipment and RTF equipment automatically advances through the channels
until the entire word count has been transferred. In this case the user supplied only the initial
channel address. In random mode, a channel address is supplied for each data word transfer,
and automatic selection is not done by the equipment.

When communicating through the RTP Handler, the following I/O calling sequence is
used:

TLO PARLIST

BLU $I/0

PARLIST DATA XX YY

DAC word count

DAC buffer address

DAC connection into buffer address

The first two parameters are as in all other DMS I/O operations. The '■bird parameter
(buffer address) is the address of the buffer from/to which the data is transferred. It must be at
least "word count" words long. The fourth parameter (connection info buffer address) tells which
channels/slots the data transfer is to be done from/to. In the case of sequential mode transfers,
only the first word of this buffer is referenced. In random mode transfers, each channel/slot
number in the connection buffer corresponds to a word in the data buffer, requiring the connec-
tion buffer - to be at least "word count" words in length. The actual format of the contents of
both of these buffers is variable depending on the device involved, and is described In the
following sections.

Common information is described below:

1. Data Buffer (First buffer address)

Bits 15-0 contain the data in/out. These correspond to RTP bits 0-15
respectively.

Bits 23-18 on input operations contain the card slot address 7420/20, 7420/
30 only) from which the data was input. These bits are undefined in all
other operations.

5-17

Revision A
May, 1974

2. Connection Buffer

Bits 10-0 contain the card slot address, channel number, gain information,
etc., as required by the particular device. These formats are given in the
following sections Bits 10-0 correspond to RTP Bits 5-15.

Bit 17 if set indicates that this transfer, and all others following it in I/O
operation, are to be done in interrupt mode regardless of the settings in
RTPTB2.

Special Note: When mixing interrupt and non-interrupt I/O in the same I/O call to
the handler - all non-interrupt I/O must precede interrupt I/O in
terms of connection buffer ordering.

Device Programming Considerations

The following sections define particular bit configurations and considerations
for all RTP modules.

9472 7435/20 Digital Input

Interrupt: Optional - external device supplied

Data Buffer:

23 18

CHANNEL
ADDRESS

15
16 bit input value

Connection Buffer:

17
IR

3
CHANNEL
ADDRESS

Special Notes: None

5-18

Revision A
May, 1974

9473 7435/22 Digital Output

Interrupt: Optional - external device supplied

Data Buffer:

Not Used

16 bit integer to be output

Connection Buffer:

17
IR

CHANNEL ADDRESS

Special Notes: None

5-19

Revision A
May, 1974

9474 7435/24 AC Input

Int-errupt: OpHonal - configuration item.

Data Buffer:

23 18

CHANNEL
ADDRESS

7
8 bit data value

Connection Buffer:

17
IR

CHANNEL
ADDRESS

Special Notes: None

5-20

9475 7435/25 AC Output

Interrupt: None
Data Buffer:

Connection Buffer:

Special Notes: None

Revision A
May, 1974

7
SWITCH OUTPUTS

1 = Switch Closed - Conducting
- Switch Open

3
CHANNEL ADDRESS

5-21

Revision A
May, 1974

9476 7435/33 Pulse Counter

Interrupt: On reaching total count of 65536 if detection of interrupt is desired, place

one-word input request to device with BI7 of connection buffer to wait for input
interrupt.

Data Buffer:

23 18

CHANNEL
ADDRESS

15
16-bit counter value

Connection Buffer:

17
IR

5
C

CHANNEL
ADDRESS

If set to 1, clear counter to 0.

Special Notes: To clear counter, do a one-word (non -interrupt) with Bit 5 of connection
Buffer Set and ignore input.

)-22

Revision A
May, 1974

9478 7435/37 Optically Isolafed Input

Interrupt: Optional - externally supplied

Data Buffer:

CHANNEL
ADDRESS

16-Bit Input Value

Connection Buffer:

17
IR

CHANNEL
ADDRESS

Special Notes: None

5-23

Revision A
May, 1974

9479 7435/38 Dry Relay Output

9480 7435/39 Mercury Relay Output
Interrupt: Optional - externally supplied
Data Buffer:

15
16-Bit Output Value

Connection Buffer:

17
IR

CHANNEL
ADDRESS

Special Notes: None

5-24

Revision A
May, 1974

948 T 7435/42 Interrupt Expander

Interrupt: Yes, use Bit 17 of Connection Buffer only.
Data Buffer (Input):

CHANNEL
ADDRESS

INTERRUPT
LEVEL

Data Buffer (Output):

INTERRUPT
ENABLE/DISABLE BITS

{1 = enable interrupt
P = disable interrupt

Connection Buffer: (I and 0)

17
Input = 1
Output =

CHANNEL
ADDRESS

Special Notes:

1. Normal programming of Interrupt Expanders through handler is as follows:

A Do output with B17 of connection buffer off to enable selected interrupts

B. Place one word input request on the card slot with B17 of connection buffer set.

C. When an interrupt occurs, determine location from buffer and repeat step B for
next interrupt.

2. Bit in RTPTN2 should be for Interrupt Expanders.

5-25

Revision A
May, 1974

9482 7435/45 Serial Input Module
Interrupt: On each input character
Data Buffer:

23 18

CHANNEL
ADDRESS

7
8 -Bit Character

Connection Buffer:

17
IR

7 6

CHANNEL
ADDRESS

1 - Set Data Terminal Ready
- Reset Data Terminal Ready

/O - No change

\l - Set TTY Reader

'GO'

00 - No change
i'l'Ol - Disable Auto Read Mode
10 - Enable Auto Read Mode
- Invalid

Special Notes:

1. The "TTY" Reader "GO" and "Auto Read" Modes are used when a TTY is
directly connected to the Serial Input Module. The Auto Read Mode,
when enabled causes "TTY Reader GO" to be set after each character is
input. The "TTY Reader GO" signal is normally applied to the Teletype
Tape Reader Mechanism to control paper tape input. When using a

Data Set, these signals are not used.

2. Start and Stop bits on the serial character are not passed into the input
character and parity is not checked.

5-26

Revision A
May, 1974

9483 7435/46 Serial Output Module

Interrupt: On each character to indicate ready

Data Buffer:

Connection Buffer:

17
IR

7 6

CHANNEL
ADDRESS

No change

Reset Request-to-Send
Set Request-to-Send
Invalid Code

Special Notes: None

5-27

Revision A
May, 1974

9 484 7435/47 Analog Input Module

9 485 7435/49 Analog Input Module
Interrupt: Yes

Data Buffer:

CARD
SLOT

EXTENDED
SIGN

11
SIGN

DATA VALUE

Connection Buffer:

17
IR

CHANNEL

NO. WITHIN

CARD

CARD SLOT #

Special Notes:

1. Dse of this card requires a bit in the appropriate word in RTPTB3.

2. "Card Slot" on this sheet refers to the channel address on the 9471 - 7430/30
Common Equipment Chassis.

5-28

9462 7445/20 Analog Output - Sample and Hold

9463 7445/21 Analog Output - Sample and Hold
Interrupt: Yes

Data Buffer:

Revision A
May, 1974

NOT USED

12-Bit Signed Integer

Connection Buffer:

17
IR

CHANNEL
ADDRESS ON 7440

Special Notes: None

5-29

Revision A
May, 1974

9451 7455/20

9452 7455/21

9453 7455/22

9454 7455/23

9455 7455/24

Analog Output Modules

Interrupt: None
Data Buffer:

23 12

NOT USED

Connection Buffer:

12-Bit Output Value

This is optionally a 12-Bit Signed Integer
depending on Card Model.

CHANNEL
ADDRESS

Special Notes:

1. These cards can be used on both of these devices:

9450 7450/20 Analog Output Common
9471 7430/30 Universal Common

5-30

9443 7465/20 High Level Analog Inpuf
9443 7465/21 High Level Analog Inpuf
Interrupt: Yes
Data Buffer:

Revision, A
May, 1974

UNDEFINED

SIGN
EXTENDED

12-BIt Signed Integer Data Value

Connection Buffer:

17
IR

CHANNEL
ADDRESS

NOT
USED

Special Notes: For devices containing these modules (7460/XX), the entire word in
RTPTB3 should be set to -1 [77777777^).

5-31

Revision A
May, 1974

9431 7476/20 Low Level Analog Inpuf

Interrupt: Yes

Data Buffer:

23 16

UNDEFINED

SIGN
EXTENDED

12 -Bit Signed Integer Data Value

Connection Buffer:

9 4

CHANNEL
ADDRESS

3
GAIN

Special Notes:

1. The Sequential Input Function will not operate on these modules. Random
must be used.

2. Consult the RTP device manual (PM070 -006/037) for information or construction
of the gain information.

3. The entire RTPTB3 word in the DMS SYSDAT must be set to -1 {77777777^) for
proper operation.

9421 7485/30 Wide Range Analog Input

9422 7485/31 Wide Range Analog Input
Interrupt: Yes

Data Buffer:

Revision A
May, 1974

23 16

UNDEFINED

16-Bit Signed Integer Data Value

Connection Buffer:

17
IR

OPEN

TRANS

DET

= +

1 = -

12 4

CHANNEL
NUMBER

3
GAIN

t 1 L

Polarity of Constant Current Source
Check for Open Transducer

Auto Range

Special Notes:

1. The Sequential Input Function will not operate on those modules.
Random must be used.

2. Consult the RTP device manual (PM 070-027) for information on the
items in the connection buffer.

3. The entire RTPTB3 word in the DMS SYSDAT must be set to -1 {77777777^)
for proper operation.

5-33

; Revision B
March, 1975

Function Codes

Sequential Read (01) - Performs an input operation to the specified device, setting
the sequential (automatic channel increment) mode, starting with the channel number In the
first element of the connection buffer.

Sequential Write (02) - Performs an output operation to the specified device, setting
the sequential (automatic channel increment) mode, and starting with the channel number
specified in the first element of the connection buffer.

Random Read (03) - Performs an input operation on the specified device, setting the
random access mode. Individual channel numbers are taken from each corresponding position
of the connection buffer for each data word input.

Random Write (04) - Performs an output operation on the specified device, setting the
random access mode. Individual channel numbers for each output data word are taken from
the corresponding position of the connection buffer.

Set Completion Variable (05) - The first buffer address of the standard parameter list
Is the address of a variable In the users program to be decremented by one whenever an input
or output operation is complete. Once this variable has been set Into the handler, it Is
decremented by one each time the device completes an operation. This variable parameter
may be cleared at any time by passing a zero address for the variable. This service allows
user programs to monitor the status of an operation by checking a variable within the program.

Open (07) - The particular RTP device Is allocated to the calling program and the
device storage area Is allocated and initialized.

Close/Deallocate (2 2) - The particular RTP device Is closed and released, allowing
other programs to open it. TfiF device storage area is deallocated.

5-2. 11 Alphan umeric CRT's

One or more CRT's are handled by a re-entrant Display Handler. Each handler Is
Interfaced by a private service routine, allowing local or long distance communications via any
standard hardware interface. Any one of the CRT's may be designated as the operator's terminal
at system generation (see Section XII). The operator's terminal may be alternately specified at
system boot time by setting sense switch one along with the desired terminal device number in
control switches zero through five, before activating the bootstrap.

The specified operator's terminal functions as a normal remote terminal in addition
to being the operator communication console. The Operator Communication Service (OPCOM)
is not accessible from any terminal other than the operator's console. The operator may
relinquish operator communications to another terminal via the command/OT,n where "n" Is
the desired terminal device number.

The re-entrant display handler honors standard lOCs requests for all CRT's including
the assigned operator's terminal. Three special characters are acknowledged when in the first
column of any input line, "/", " \ ", and "1 ". The "/" signifies an OPCOM input statement.

5-34

Revision B
March, 1975

" \" signifies a terminal abort request, and " ±" signifies a handler mode command. The
handler treats line zero as an Input media, and lines 1 through 23 as an output page. A
symbolic write below line 23 is handled as determined by the current handler mode. Three
handler modes are available. In the "scroll" mode (which is the default mode), a symbolic
write below line 23 is written on line 23 after line 1 has been deleted and lines 2-23 have
been scrolled up one line. In the "page" mode, the screen is erased and the line is written
on line 1. In the "wait" mode, an uparrow (A) character is output in the home position and
the handler waits for the user to enter a transmit. When the transmit is received, the screen
is erased and the line is written on line 1.

The handler modes are selectable from the terminal by entering a "±S" for scroll,
"IP" for page, and "±W" for wait mode. The modes may also be set by the use of function
code 17* (Set Handler Mode).

5-34A

Revision B
March, 1975

When an OPCOM statement Is detected, the display handler makes sure that the
terminal is the currently allocated console device, and then passes the statement to Operator
Communications. If a regular IOCS input request was pending, it is re-initialized after the
OPCOM statement has been passed.

A terminal abort request causes the I/O Executive to abort the foreground program
currently connected to the terminal, and clears the screen of the display.

If an input statement is transmitted and no request is pending the statement will
remain displayed and a handler flag set until an input request is made, at which time the
statement is accepted and the line cleared. If an input request is made by a program and no
data has been transmitted, the request Is saved but the device remains "not busy" to permit
output requests. When a transmit is detected, the pending input is processed.

Standard IOCS functions are listed below with a description of their operation.

Status (00) - A normal status word Is returned in Register A and the condition register
is set as a function of A.

Symbolic Read (01) - The user's buffer Is blanked and up to 80 input characters,
packed 3 characters per word, are accepted. A "$EOF" statement Is defined as an Input end-
of-file. The parameter "n" specifies the word count to be input.

Symbolic Write (02) - Up to 81 characters are transmitted to the next available line
of the output page. Column zero (carriage control) is Ignored. Data is assumed to be packed
three characters per word ASCII. The parameter "n" specifies the word count to be output.

Edit Read (03) - "n" characters are accepted from the specified cursor position and
packed in the user's buffer three characters per word. The calling sequence for this request Is:

DAC 'XX03

DATA n

DAC Buffer address

DATA /0,row,col/ where 8 bit bytes per field are used.

The cursor position Is saved and restored to its original position at the end of the operation.

Edit Write (04) - Outputs "n" characters at the specified cursor position. The calling
sequence is:

DAC 'XX04

DATA n

DAC Buffer address

DATA /0,row,col/ where 8 bit bytes per field are used.

The current cursor position is saved and restored to its previous state at the end of the output
operation.

5-35

Revision C
November 1975

Operator NAessage (05) - Outputs six character message on line one in column 75
through 80. The calling sequence is as follows:

DAC 'XX05

DATA n

DAC Buffer address

The character count "n" must be adequate to include "blink" and "unblink" codes, if present,
but should not exceed six.

Input Wait (05*) - If a parameter one (character count) of a function 05 call is zero,
the calling program is placed in a wait until a transmit code is detected from the keyboard.
No transfer takes place.

Write End-of-File (06) - Writes the output message "EOF. . " on the next available
output line.

Open (07) - This function sets the output line number for top-ot-page (first output
line).

Rewind (16) - This function erases the current display page and sets the output line
number for top -of -page (first output line).

Set Line Number (17) - Sets the output line pointer to the specified line number. The
calling sequence is:

DAC 'XX17

DATA line number (1 for first output line)

Set Handler Mode (17*) - If the parameter of a function 17 call is negative, the
handler mode is set as specified by the parameter. Valid parameters are: -1 for scroll mode,
-2 for page mode, and -3 for wait mode. All other negative values are invalid. The calling
sequence is:

DAC ■XX17

DATA parameter (-1,-2, or -3)

Set/Reset Data - Panel Lights ( 17**) - jhis function turns the data-panel lights on
or off as specified by the parameter. On CRT' s not equipped with data-panel lights, this is
a null function. The lights to be turned on or off are specified, one bit per light, in bits 0-15 of
the parameter word. Lights not specified remain unchanged. Bits 23-21 of the parameter word
determine whether the specified lights are to bie turned on or off. A 6 in this position ( B23 B22
set, B21 reset) will turn off the specified lights, a 4 in this position ( B23 set, B22 B21 reset) will
turn on the specified lights. The calling sequence is:

DAC •XX17

DATA parameter

5-36

Revision C
November 1975

Gef Cursor Address ( 20) - Refurns Row/Column In register E, bytes 2 and 1 respectively
(high order bits of E are zero) of the current cursor position.

Set Cursor Address (21) - The CRT cursor is position to the specified row and column.
The calling sequence Is:

DAC 'XX21

DATA /O,row,columiy' where 8 bit bytes are used for fields.

NOTE

"row" specifies a horizontal row between and
23 where row is the input line and rows 1-23
are the output page; and "column" specified
the vertical column number between 1 and 80.

Functions greater than 22 are invalid and all
others are "null".

5-36A

Revision 8
March, 1975

5-2, 12 Reader/Punch

The reader/punch may be considered to be logically two separate devices, either a
card reader or card punch. Depending on the entry point referenced, the unit will perforrn the
specifred opLtion for that logical device. A word in the SYSTEM DATA MODULE RPAMOD,
allows access to one or both of the logical devices. The "mode word" .s defined as follows:

"RPA MOD" DEVICE

Negative Reader Only

Zero Reader or Punch

Positive Punch Only

A reference to the punch when in "reader only" mode will generate an abort, ABT 10.

In the "reader and punch" mode, the device will be used as a card reader until a
$CLOSD card is read. At that time, the device is allocated to the first program needing the
device. The logical device opened first will determine whether the device will read or punch.

For example, to spool in a job which generates punch output the following procedure
could be followed:

Spooling in Jobstream
$JOB. . .

$EOJ

Deallocate the spool in card reader
$CLOSD

BLANK CARDS

The program will produce punch output on cards. Upon a close to the punch, the
extra blank cards will be flushed and offset until the first non-blank card is detected by the
reader.

5-2.12.1 Card Reader

Card input is buffered and converted according to the IOCS input request. Some
special checks are made by the handler before allowing a transfer to the user buffer.

A card image of "$26" in columns 1 -3 is thrown away and the H026 code conversion
flag is set. A "$29" card sets the H029 flag. H029 is assumed as default. A 9/8 multi -punch
in column one is defined as an EOF record.

5-37

Revision A
May, 1974

All other records are passed to IOCS and tested for "$" job control statements. If
the/ pass these tests, data is passed to the user buffer according to the following function requests.

Symbolic Read (01) - A single 80 column card is converted from 026 or 029 code to
nternal ANSCII, three characters per word, until the user's buffer is filled (byte 81, and all
)ther words greater than 27 (if any) will be blank).

Symbolic Write (02) - Invalid function code.

Binary Read (03) - Consecutive cards are accepted and passed to the user's buffer,
until the specified word count is satisfied or until an End-of-Record card Is detected. Binary
cards are formatted as follows:

o Column 1 - Reserved for a special action code: A 9/8 multi -punch signifies
an End-of-File record, and a 9/7 multl -punch is a partial code signifying that
this card does not complete the binary record.

o Column 2 - Blank.

o Columns 3 through 6 - Reserved for a user sequence number.
The handler Ignores 2-6.

o Columns 7 through 80 - Contain 12-bIt binary data allowing 37 data words
per card, at 2 columns per word.

Binary Write (04) - Invalid function code.

Hollerith Read (05) - A single 80-column card Is transferred to the user's buffer,
without conversion, and packed two columns per word.

Write EOF (06) - Invalid function code.

Reposition File (11) - Operator hold message "RPF CR" Is typed.

Backspace File (12) - Operator hold message "BSF CR" Is typed.

Advance File (13) - Cards are input until an End-of-File card (9/8 multi -punch
in column 1) Is detected.

Backspace Record (14) - Operator hold message "BSR CR" is typed.

Advance Record (15) - Cards are input and Ignored until a card not containing a
y// multi -punch in column 1 is detected.

Rewind (16) - Null.

5-38

Revision A
May; 1974

Set Current Record Address (17) - Null.

Seek Current Record Address (20) - Null.

Set Current File Address (21) - Null.

Close/Deallocate (22) - The device is deallocated from the calling program.

Special Open (23) - Null.

5-2.12.2 Card Punch

The following is a list of the I/O functions and their definitions for the card punch,

Symbolic Read (01) - Invalid Function Code.

Symbolic Write (02) - Converts ANSCII to Hollerith core and punches 1 card.
Conversion code is assumed to be H029 unless system option 23 is set, requesting H026
conversion.

Binary Read (03) - Invalid function code.

Binary Write (04) - Punches one or more cards as a binary record. Column 1 of each
card is reserved as a special action code. A 9/8 multi -punch in column 1 indicates an End-
of-File record (one card). A 9/7 multi -punch indicates a partial record. Columns 2 through
6 are open for a sequence number (the handler does not generate a sequence number).

Special Action (05) - Punches 80 columns, 2 columns per v^ord, unformatted.

Write EOF (06) - A 9/8 multi -punch is punched in column 1.

Open (07) - The device is allocated to the calling program.

Close (10) - A blank card is punched.

Reposition File (11) - Invalid function code.

Backspace File (12) - Invalid function code.

Advance File (13) - Invalid function code.

Backspace Record (14) - Invalid function code.

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Revision B
March, 1975

Advance Record (15) - Invalid function code.

Rewind (16) - Null.

Set Current Record Address (17) - Invalid function code.

Seek Current Record Address (20) - Invalid function code.

Set Current File Address (21 ) - Invalid function code.

Close/Deallocate (22) - The device is closed and deallocated from the user's program.

Special Open (23) - Invalid function code.

5-2. 13 Printer/Plotter

The printer/plotter allows two modes of operation. A "symbolic write" request instructs
the device to function as a normal list output device. A "binary write" request instructs the device
to perform as an electrostatic plotter. The device handler is non -re -entrant and is executed via
the standard IOCS calling sequence. The following is a list of valid function codes and the action
associated with each code.

Symbolic Write (02) - Write a symbolic logical record in the print mode. The
buffer is assumed to be ASCII symbolic code packed three characters per word, preceded by a
carriage control character in the first position in the buffer. Although the printer/plotter does not
perform as a standard hard copy print device, it is physically unable to allow the same degree of
control exhibited by most "line printers". Notably, there is no VFC or "carriage tape" nor is there
a facility for remaining on the same line and "overprinting". Thus, only a restricted set of carriage
control characters is honored (all others are effectively treated as a blank): The valid carriage
control characters are:

" " (blank) - advance to next lin e and print.

" ^ " - Advance to next page - A "form feed" is issued.

On a device with the "fan-fold" option a physical top-of-form is issued.
A device without the fan-fold option will advance the paper 2 1/2 inchejs.

"0" - Double Space - Leave a blank line before printing. '

•■ " - Operator HOLD message . The following line is printed at the OPCOM
device and the user program is placed in the HOLD state.

If the word count specified is greater than the physical line length then the record will be
truncated. All "unprintable" characters are effectively "null" and thus ignored.

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Revision B
March, 1975

Binary Write (04) - The buffer is considered fo be a packed bit string. Since the
physical plot butter is an integral multiple of bytes (8 bits) and not words, a single request to
plot multiple lines would require that the plot records span across words (the second and sub-
sequent records are not guaranteed to be word alligned), A "1" bit designates that the nib in
that position should print, a " " bit designates absence of print. The word count is software
truncated to an integral multiple of plot lines.

Write EOF (06) - Included for system wide compatibility. Effectively a null operation.

Open (07) - Logically opens the device. An EOT action Is taken which will advance
the paper eight inches, clearing it from the ink reservoir. An open must be issued prior to any
other logical I/O operations.

Rewind (16) - Included only for system wide compatablllty. Effectively a null operation.

Close ( 1 0) - Logically closes the device.

Close/Deallocate (22) - Logically close the device and allow It to be assigned to
another useT^ An tOI action will be taken to insure that the paper does not stand In the ink
reservoir.

All other logical Input/output operations are invalid and the program issuing such a
request will be aborted.

As an additional note, care should be taken to drive the printer/plotter at an even
rate near its maximum speed; otherwise, Inertlal errors may occur (which may cause an uneven
appearance In the quality of the print).

5-2. 14 Incremental Plotter

The plotter may be driven directly by a user program or the special foreground
program "S. PLOT". The initial open after a reboot will output the message "POSITION PLOT"
to the operator console and will suspend the program. Once the operator has positioned the pen
to 1/2 Inch from the Z-fold, the program may be released. Thereafter, the Z-fold position is
maintained by the handler. This enables direct plotting with or without use of the plot support
library.

The following Is a list of the I/O functions and their definitions. All others are null.

Symbolic Write (02) - The handler outputs three 8-bit plot commands for each word
in the user's buffer. — Ihe data Is unpacked and transferred on an interrupt basic until the word
count Is complete.

Binary Write (04) - Identical to the symbolic write (02).

Special Action (05) - The handler outputs one 8-bIt (7-0) plot command for each word
In the user's butter. Iranster continues until the word count is complete.

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Ope" File (07 ) - The handler will perform a page restore if the pen Is not correctly
positioned at a Z-fold. The initial open after a reboot will output an operator message requesting
the pen to be positioned.

:iose File (10) - The handler will perform a page restore if the pen is not correctly
positioned at a Z-told.

Close/Deallocate (2 2) - Closes the device as with function 10 above, if not already
done, and deallocates the device from the calling program.

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SECTION VI
BACKGROUND BATCH PROCESSING

6-1 JOB STREAM

Under DMS, the background input stream is considered the "Job Stream Input
File". This is defined as the file or device to which Logical File 00 (Job Stream) is
assigned. A number of special features effect the Job Stream Input File. These are
discussed below.

6-1. 1 Special Assignment (Spooled Systems only)

Under DMS, one does not always know to what file or device his job stream
is assigned. This is particularly true in the case of spooled input, since under spooling
job stream is assigned to a particular file on disc, the name of which is not immediately
available to the programmer. To assign any logical file to use the same file or device as
job stream, one merely assigns the LFN to Physical Device 77g. The I/O control supervisor
will automatically transfer the request to Physical Device 77 to the Job Stream File. Thus
the assignment

^.ASSIGN 7,77

will assign the Source Input (LFN 7) to use the Job Stream Input File. This feature is not
available in unspooled DMS configurations.

6-1.2 Reading "$" Cards

Whenever a card containing a dollar sign ($) in column 1 is read from the
Job Stream file or device by any processor other than Job Control, special action occurs.
Under these circumstances, DMS will: 1) Copy the "$" card to the resident Job Control
buffer, 2) Set the system "trap" flag so that Job Control can process this record, 3) Return
the card image containing the "S" to the user's buffer, and 4) Return the end-of-file
status to the calling program.

If the processor performs another read request to the file without clearing the
"trap" flag via the UNTRAP service, the processor exits and Job Control will be loaded and
will attempt to process the record. If the "trap" flag is cleared, (see paragraph 4-16) then
further reads can be made.

6-1.3 File Insertion Feature

The File Insertion feature, available in spooled DMS systems only, allows
the insertion of a specified disc file in the Input Job Stream at any point. This is
accomplished by using the $ADD card which is written as

$ADD FILNAM

This card effectively causes the contents of "FILNAM" to be inserted in the job stream in
place of the $ADD card. The $ADD card may be placed anywhere in the job stream, in
particular, in the middle of a data deck, etc. The $ADD card is transparent to all back-
ground processors. If "FILNAM" is non-existent, the message "»$ADD FILNAM NON-EXISTENT"
will be output to the list output device and the job will continue.

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I Revision C
November 1975

The file whfch is being ADDed must be terminated with a $RETUi^N control card.
When DMS reads this record, the next image returned to the calling program will be the next
line following the previously encountered $ADD card. No password may be used on ADD files,
and $ADD cards may not be nested.

The SADD card may not be used In jobs read in the unspooled mode (see para-
graph 8-6. 1).

6-2 JOB CONTROL PROGRAM

Job Control (JOBCTL) is a special system program that is loaded and
executed in the DMS background whenever the system is initialized and whenever any
background program is terminated. Job Control executes in the unrestricted mode such
that it can modify resident DMS tables as necessary to direct background processing. _
JOBCTL accepts control statements from the input device assigned to job Stream (logical
file 0), outputs each statement to logical file 6, and then processes valid statements as
described in subsequent paragraphs of this section. Invalid statements cause an abort
with the message "JCL ERROR" output to logical file 6. Invalid statements entered from
the operator communication device (LFN assigned to device 1) cause an operator hold
message. A release command is required to continue.

If job stream is assigned to some device other than the console typewriter,
the SJOB statement is required following an ABORT condition; all other statements are
accepted and ignored until a SJOB is received.

Job stream can be reassigned to the console teletypewriter at any time via
the operator communications statement (JC). This does, however, abort the execution of
the current background job, as well as slow down the execution of other jobs by holding
background operation to the operator console.

6-2. 1 ' UOB Statement

This statement transfers the job name to the Background Information Area,
resets all background flags, options, and lines and sets logical device numbers to their
default assignments (as specified during SYSGEN). Additionally, the job name Is printed
on the console teletype. The format is as follows.

^JOB name

where: name consists of zero to six ANSCIl characters.

On spooled systems, additional parameters may be used to specify other than
default parameters. The general form of the spooled job card is

SJOB name Unnn Pnnn Dnn Lnnn Innn Tnn Mnnn

where: name consists of one to six ANSCIl characters.

Unnn Is the user number and is valid and required only In accounting
versions of DMS (see Section VII).

Pnnn Is the priority; nnn must be between 1 and 254 and must conform to

the established input terminal priority (see Section VIII). The priority

value specifies the relative priority in the background spool Input queue.

It does not effect the priority of background execution, which is fixed at

255.

Tnn is the time limit in seconds for the execution of this job (accounting systems

only). If not used,the system default time limit is used.

6-2

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6-2.2 $EOJ Statemenf

This stafement signifies fhe end of the current job and must be present to
terminate the background job. The message "EOJ" is output on the console teletype. In
accounting systems, the CPU execution time of the job is printed on the assigned List Output
File. The format is:

$EOJ

6-2.3 $AS5IGN Statement

This statement causes the specified Logical File Number ( LFN) to be assigned
to a Physical Device Number (PDN), a Disc File Name (DFN), or a Spooled Device
number (SDN). Thereafter, when any background program executes an ]/0 request with
the specified logical file number, DMS will utilize the device or disc file that was
assigned to the logical file number with this statement. The format is as follows:

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(NOTE: An equal H sign or comma {,) may be used interchangeably between UFN and
PDN, DFN or SDN):

^ASSIGN LFN, PDN, LFN, PDN, ...
4;ASSIGN LFN=PDN, LFN=PDN, ...

ASSIGN LFN, DFN, LFN, DFN, ...
^ASSIGN LFN=DFN, LFN=DFN,...

$ASSIGN LFN, #SDN, LFN,/SDN(file size)
^^ASSIGN LFN=#SDN, LFN=#SDN(file size)

Invalid values for the LFN, PDN, or SDN will result in a "JCL error" and
termination of the Job. ( See Section 4-13, ASSIGN Service for a definition of valid
values for LFN, PDN &SDN.)

The latter format is used to assign an output Logical File to a Spooled File.
A spool file will be dynamically created and will be spooled out to the specified device
when the job is completed. If the optional "(file size)" field is oresent, ^his size in
sectors will be used as the size of the file. Otherwise the default size will be used. The
specified device number must be a spooled terminal device. Some examples of assignments
are given below.

1) <bASSIGN 5,10

This assignment specifies that Logical File 5 (Binary Output)
is to be assigned to Physical Device lOg.

2) SASSIGN 6,0

This assignment specifies that all output to Logical File 6 is to be
iop'^red

J) SASSIGN 16,W1

This statement specifies that Logical File I6g is to be assigned to
disc file "Wl".

4) SASSIGN 3,#10(50)

This statement specifies that output to Logical File 3 is to be
spooled out to Physical Device iOg using a disc file of 50 sectors.

6-2. 4 SPATE Statement

In non-accounting versions of DMS, this statement transfers the specified nine
ANSCII characters or less to the background information area date storage.

6-4

The formal- Is as follows.

$DATE xxxxxxxxx

In accounfing systems, the statement is ignored as the system date Is
established when DMS Is loaded from disc.

6-2.5 SLINES Statemen t

This statement alters the default number of lines per page for listed output.
The format Is a follows.

SLINES n

The default is returned at the beginning of the following job.

6-2.6 ^OPTIONS Statement

This statement sets the specified bits of the Options word; i.e., places 1 's
in the selected bit positions (n Is a decimal integer less than or equal to 23). The
leading dot (. ), if present, enters Zeros (0) in all bits of the word prior to setting the
specified bits. The Options word is acquired by the service INFO. The format is as
follows.

$OPTIONS . 1,2,3, 4,..., n

The usage of OPTIONS settings by standard DMS routines and processors Is
given in Appendix D.

6-2.7 '^FLAGS Statement

This command functions In the same manner as the SOPTIONS statement,
except that a different memory location Is used. The format is as follows.

$FLAGS .0,l,2,...,n

The FLAGS values used In assembling DMS modules and processors are listed
in Appendix D.

6-2.8 SINCLUDE Statement

This statement Is used to copy program elements in link module form as
produced by the Fortran Compiler or Macro Assembler, from one device to another. The
basic format Is as follows.

"illNCLUDE (Filename, password)

If no file name Is specified, input is from Logical File 04 (Binary Input). If
a file name is specified, this file Is rewound and used as the Input source. JOBCTL
copies link modules from the Input file to Logical File 05 (Binary Output), which is
normally assigned to the Link Ready disc file ("LR"), until an end-of-file is encountered.
At that time an end-of-file Is written to Logical File 05 and this file is backspaced a
record in anticipation of another $INCLUDE statement, an assembly or a compilation.

6-5

6-2,9 $C ATA LOG Statemen t

This statement causes the Link Cataloger to be loaded and executed. The
Link Cataloger accepts specification cards that follow the SCATALOG, builds a load
module from the routines on the Link Ready file (together with required library subroutines),
and outputs the load module to a disc file. The resultant load module is not executed
as a direct result of this statement. The format is as follows.

SCATALOG

Refer to paragraph 6-4 for additional information.

6-2. 10 SCATGO Statement

This statement sets the GOFLAG, then executes the Link Cataloger which
catalogs onto the system "GO" file for immediate execution. The format is as follows.

$CATGO

Refer to paragraph 6-4 for additional information.

6-2. 1 1 $LOADGO Statement

This statement causes the specified background program to be loaded and
executed in the DMS background. The specified program must nave been previously
cataloged via $CATALOG. The format is as follows.

SLOADGO programname

When initiated, the A register is loaded with the address of the background
job control buffer, which contains the image which caused the program to be started,
allowing user programs to interograte the line for options, parameters, etc.

6-2. ]2 $HOLD Statement

This statement causes the first 15 characters of the specified text to be out-
put to the operator communication device and the background enters a wait condition
until the operator intervenes (refer to Section IX, Paragraph 9-1). The format is as
follows.

SHOLD text

6-2. 13 STAPEOP Statement

This statement is used to select the tape transport mode, density, and
characters per word specification for a specific tape transport for the duration of the
background job, or until another STAPEOP is encountered. Execution of this statement
will not effect ony foreground magnetic tape operation (see paragraph 5-2.3). The format
is as follows.

STAPEOP transport, mode, density, cpw.

where the ordering of the parameters is insignificant and transport is of the
form TO, Tl, T2, or 17 specifying the transport number;

mode is one of "BINARY" or "ASCII" for no conversion or "BCD" for IBM

6-6

compatible BCD conversion (7-track only) or "EBCDIC" for ebcdic conversion {9-track
only);

( 200)
density is of the form) 556UBPI) where "BPI" is optional and the number
represents tape density; j 800 (

(I6OO;

Cpvv is of the form 1 2 ( ( cpw) v/here "cpw" is optional and the value represents
the number of characters per )3 C word. Note that for valid BCD or EBCDIC conversion,

3 characters per word must be \4) specified. Characters will be right justified in the
user's buffer, with unused portions filled with zeroes; the absence of any parameter spec-
ifies that the system default will be used. For example, the statement

$TAPEOP T0,1600,2CPW

specifies that transport is to be used for default (normally binary) conversion,
but use 2 characters per word at a density of 1600 BPI.

6-2. 14 $ADUMP Statement

This statement is used to produce a memory dump of a portion of the back-
ground memory area when a background program aborts. The format is as follows.

$ADUMP a,b

where a is the initial relative memory location (octal) at which the dump is
to start, and

where b is the ending relative memory location which defines the end of the
area to be dumped.

Both memory addresses are relative to the start of background. If either or
both are absent, the start or end of background, respectively, are used as the bounds
values for the dump. Whenever a background processor aborts with this statement active,
the dump is written to logical file 6. If a processor exit normally, the SADUMP request
is cancelled. Thus, this statement must be used immediately prior to the execution of
each processor which may cause an abort.

6-2. 15 $QPEN Statement

This statement opens logical file xx (octal) using the specified password
yyyyyy. The format is as follows.

$OPEN XX, yyyyyy

The password field is required only if the file has a password.

6-2. 16 $CLOSE Statement

This statement closes logical file xx (octal). The format is as follows.

$CLOSE xx

6-7

6-2, 17 $REW Statement

This statement rewinds logical file xx (octal). The format is as follows.

$REW XX

6-2. 18 $BSF Statement

This statement backspaces one file on logical file xx (octal), The format
is as follows.

SBSF XX

6-2. 19 $ADF Statement

This statement advances one file on logical file xx (octal). The format is
as fo Mows.

$ADF XX

6-2.20 $RPF Statement

This statement repositions the current file on logical file xx (octal). The
format is as follows.

SRPF XX

6-2.21 $WEF Statement

This statement writes an End-of-File on logical file xx (octal). The format
is as follows.

$WEF XX

6-2.22 $XXYY Statemen t

This statement performs function yy (octal) on logical file xx (octal). The
format is as follows.

$XXYY xxyy

A Table of j/O function codes is given in Section V, Table 5-3.

6-2.23 $EDITLF Statement

follows.

This statement loads and executes the Library File Editor. The format is as

SEDITLF

For additional information, refer to paragraph 15-3.

6-8

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6-2.24 SFILEMA Sfafement

This statement, loads and executes the File Manager. The format is as follows.

$FILEMA

For additional information, refer to paragraph 6-3.
6-2.25 $NAME Statement

as follows.

This statement is equivalent to a $LOADGO name statement. The format is

$NAME

Refer to paragraph 6-2.11. For example, the statement $FORTRAN is
equivalent to $LOADGO FORTRAN.

6-2.26 S Comments Statement

This statement causes no action to be performed. It is used only for intro-
ducing comments onto the List Output File. The format is:

$ comments

where the blank character in column 2 is required.

6-3 FILE MANAGER

The File Manager performs functions that are associated with the utilization
of the DMS file system. The user should be familiar with the material discussed in
Section III of this manual prior to using this program. The File Manager is initiated via
the following job control statement:

$FILEMA

Once loaded, the File Manager reads directive statements from the Job Stream
Logical File. The general format for these commands consists of an alphabetic function
starting in the first character position, followed by multiple parameters, as shown below.

FUNCTION paraml,param2,param3, . . .

Parameters are separated by a single blank or a comma. A double comma is' used
to indicate that a parameter is missing, and not needed. Two consecutive blanks may also be
used in place of a double comma to indicate a missing parameter. The format sequence "comma,
blank, comma" is functionally the same as three successive commas.

The format of the Master Disc Directory (MDD) may be found in Appendix C. The
SAVE/RESTORE formats may be found in section 6-3.29.

The File Manager will output to LFN 6 pertinent data for commands which may
reference a group of file names. The following information may be provided for each file,
depending on the command:

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Revision C

November 1975

Data and Time

File name

Pack number

First sector number

Last sector number

File size in sectors

Type

User access

Memory requirements

10.

Absolute load origin

11.

User number

•12.

Password

A new title will be output on every page. The page size may be varied with the
job control SLINES command. To obtain a list with only one title line, a very large value on
the lines per page job control statement should be used.

The following is a summary of the functions available within the File Manager.
Additional infonnation and the specific formats are discussed in the following paragraphs.

6-3.1

1. CREATE -

2. ESTAB-

3. DELETE-

4. RENAME-

5. DMAP-

6. DMAPS-

7. DUMP-

8. DUMPBF-

9. SAVE-

10. SAVEP-

11. SAVPAK-

12. SAVUSR-

13. LIST-

14. RESTORE

15. RESPAK-

16. RESUSR-

17. SAVMDD-

18. REPSYS-

19. CLEAR-

20. ZEROPK-

21. READPK-

22. FLAGPK-

23. ADVANCE -

24. REW-

25. WEF-

26. ADF-

27. BSF-

28. HOLD-

29. EXIT-
CREATE Statement

Generates a file

Generates a file from an LFN

Removes a file

Change the file name only

Disc directory of all files

Disc directory (secjuentially)

Generates an absolute load module

Generates an absolute load module (no parameter record)

Produce a backup of a file

Produce a backup of a file (no protection retained)

Produces a backup of all files on a pack

Produces a backup of all files by a user number

Verifies and list all files on a 'save' tape.

Recreates a file previously ' saved' .

Recreates all files for a pack

Recreates all files for a user number

Saves MDD entries for pack during sysgens.

Rewrites the resident DMS on the disc.

Identifies a new pack to DMS

Performs a "clear" and then zero's entire pack.

Reads a pack and outputs error messages upon read errors.

Flags unreadable sectors of a pack with "permanent" files.

Position to next header record (no error checking)

Rewinds specified LFN

Write an end-of-file on specified LFN

Advance one file mark on specified LFN

Backspace one file mark on specified LFN

Suspends background with a message.

Returns to the system,.

This statement directs the File Manager to allocate sequential disc space and
create an entry in the Master Disc Directory. The file name, password, and in accounting
systems, the user-number combinations must be unique within the directory as discussed in
Section III. Sufficient contiguous disc space must oe available for the file to be created.
In accounting versions of DMS, the current background user number is stored with the file
entry as the creator. The format for this statement is shown below.

Revision C
November 1975

CREATE name,password,pack^,3ize,type,reacl,write,delete, sector

name - consists of one to six characters, of which the first must be alphabetic.

password - consists of one to four characters, of which the first must be alphabetic.
A zero should be used to indicate that the file is "public" and no
password is required. Once a file has been created with a non-zero
password, any program desiring to access the file must supply a match-
ing password when the file is opened.

pack''' - consists of one to three numeric decimal digits specifying the pack ID
number of the disc pack on which the file is to reside. The main disc
on which the resident system resides is considered to be pack one. If
the requested pack is not currently mounted, the operator will be
informed.

size - consists of a decimal number specifying the desired file size in sectors.

type - consists of a single numeric character optionally preceded by "B" or

"C" or both defining the file type as follows.

Value Type of File

] User data or work file.

4 Object Library file.

5 Source Library file.

6 System work file.

Bx A "B" preceding any of the above specifies that the file

is to be typed as a "blocked file".

Cx or A "C" preceding any of the above combinations specifies

CBx that the Master Disc Directory for the file will be stored

in the core resident directory buffer.

read - An "R", "W", or "D", respectively, as additional parameters, valid
write only in accounting systems, specifies that the associated access bit is

delete to be set to allow users other than the creator to perform the specific

functions on the file. All, none, or any combination of these characters
may be present, each as distinct parameters separated by commas.

Sector - This optional parameter is used to specify a lower bound when allocating
disc space for a file, i. e. , the file will not be created if there is not
room above this loca'^ion.

6-3. 2 ESTABLISH Statement

The ESTABLISH statement is used to build a permanent file from the specified work
file.

Prior to establishing a named file, the temporary work file must control recorded data.
This recorded data can be placed on the work file in many ways.

6-11

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November 1975

For example, a link module can be placed on the work file by assembly with the binary
output assigned to the work file. Also a module can be transferred from a selected binary input
device to the work file using the job control service ($INCLUDE).

ESTABLISH assumes the current record address (CRA) of the specified work file to be
positioned at the end of the recorded data, and uses the (CRA) to determine the size of the file
to be built. A call to the DMS system service ($SYS) is made to allocate the required disc space,
then data is transferred from the work file and copied into successive sectors of the named disc
file. After all records are copied, the procedure is terminated by writing an end-of-file sector.

Statement formats are defined as follows.

I:STAB, XX,name,password,pack%size,type,read,write,delete, sector

XX - Decimal (or octal if preceded by apostrophe (')), Logical File code

assigned to the work file which is to provide the data to be established.

name - One-to-six character identifier of the file to be established, of which
the first must be alphabetic.

size - should be entered as zero because it is computed from the CRA.

frassword -should be entered as defined for the create statement, w'>th the exception

frack* that the absence or presence of the blocking specifications "B" is

type ignored in the file type designation, and the new file Is automatically

read given the same blocked/unblocked status as the work file,

write

delete

Sector - This optional parameter is used to specify a lower bound when allocating
disc space for a file, i. e, , the file will not be created if there is not
room above this location.

6-3.3 DELETE: Statement

The DELETE statement removes a specified frle name from the directory and releases
its allocated disc space. The format of this statement is as follows:

DELETE name, password

where "name" and "password" are as defined for the CREATE statement.

6-3.4 RENAME Statement

This statement permits the user to change the name, password, file type or, in
accounting systems, the protection status of any specified disc file. A monitor service Is
employed which finds and loads the Master Disc Directory entry, validates the parameters,
replaces effected information, and restores the directory entry. The format is as follows:

R E NAM E ol dnam e, newname,ol dpassword, newpassword, type, read, wri te, de I ete

oldname - required to identify existing file.

newname- optional new file name. If the field is omitted, the name remains
unchanged.

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November 1975

oldpassword - required to identify existing file if it has a password. The
parameter may be omitted if the file has no password.

newpassword - if a password is specified here, it will be the new file pass-
word. If a zero is entered in this field, the current password
is removed and the file will not have a password. If the
field is omitted, by entering consecutive commas, the current
password remains unchanged.

type

read

write

delete

A "C" or "NC" may be entered here to indicate that the Core
Resident Directory entry status is to be added ( "C") or removed ("NC")
from the type designation. No other file type changes are permitted.

- These parameters are valid only in accounting systems and are usfed
to indicate the new file access status. An "R", "W", or "D"
correspondingly, or any combination of them, is used to indicate
the respective file access. If no parameters follow the type field,
then the protection status remains unchanged. The file may be
changed to totally private (no access bits sets) by entering a single
parameter "P" to indicate private.

6-3.5

DMAP Statement

The Disc Mop Statement directs the File Manager to produce a file system disc
allocation map on the list output logical device. The file names are sorted by alphanumeric
sequence prior to output file.

where n is a disc pack number and causes only the disc
pack named to be mapped.

where nnn is a user- number and only programs with the
given user-number are mapped.

where name is a file name and only programs with the
specified name are mapped.

with no parameter specifies that the entire directory is
listed.

6-3.6

This statement performs identically to the DMAP statement defined above, except
that the map is ordered by sector number, rather than alphabetically.

DMAP n

DMAP Unnn

Hi)

DMAP name

iv)

DMAP

DMAPS Statement

6-3.7

DUMP and DUMPBF Statements

These statements cause a specified cataloged program file to be loaded into
the background memory area and dumped in an absolute load format on the assigned binary
output file. Address relocation is performed according to specified parameters.

The DUMP output consists of two binary records. Record one is a 6-word
parameter record containing the program name, low, high, start and checksum. Record two
consists of a n word data record, program low through program high.

6-13

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The DUMPBF output consists of only the n word absolute data record, producing
a bootstrap format record. ( The user should take care in coding a program for paper tape or
card bootstrap loading, to insure that there are no zero instruction or data words. The bootstrap
loaders terminate input upon detection of a zero word.)

Statement formats are defined as follows.

DUMP, name, relative program origin, absolute dump bias
DUMPBF, name, relative program origin, absolute dump bias

where: name is a one-to-six character identifier, of which the first must be
alphabetic.

relative program origin consists of a numeric value and is the relative program
origin specified in the source program (0 if not specified).

where: absolute dump bias consists of a numeric value specifying the absolute
memory address at which the program is intended for execution.

Address relocation is accomplished by adding the dump bias minus the program
origin.

6-3. 8 SAVE Statement

The SAVE statement directs the File Manager to output the entire contents of
a specified disc file to the binary output logical device ( Logical File number 5). This data
consists of a header record that preserves the file definition (name, password, type, size, etc.)
and a checksum for the record. Each data record consists of one sector of disc data plus a check-
sum for the record producing records of 1 13 words. The header record contains a sector count for
the file which defines how many data records follow.

The specified file is not deleted by the process of saving it on the binary output
device. The format of the statement Is as follows:

SAVE name, password, Unnn, newname, newpass

name - file name to be saved.

password - file password is required if the file has a password.

Unnn - is the user-number and is valid only in accounting systems. This number
is required only if the file Is totally private (has no access bits specified)
to select the proper copy of the file.

newname- is an optional parameter which becomes the file name stored in the
Save Module. This allows a file to be saved under a different name
than on the current system. If this parameter is not present, the
original file name is used.

newpass- is an optional parameter which becomes the password for the file stored
in the Save Module. This allows a file to be saved under a different
password than on the current system. If this parameter Is not present,
the original password Is used.

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6-3.9 SAVE P Statement

The SAVEP statement performs Identically to the SAVE statement discussed above
in non -accounting systems. In accounting versions of DMS, the SAVEP statement performs the
same function as the SAVE statement, except that all file protection bits and the user-number
are cleared to zeros. This allows the resulting SAVE module to be reloaded on a non-accounting
system. The format is as follov/s:

SAVEP name, password,user-number,newname,newpass
6-3.10 SAVPAK Statement

The SAVPAK statement enables all of the disc files on the specified disc pack to be
saved on the binary output logical device. The statement is equivalent to a string of SAVE
statements for each disc file on the given disc pack. The files are saved in alphabetic order and
the fomiat is as for the SAVE statement. The name of each file that is saved is listed on the list
output logical device. Upon completion of the entire group save, an end-of-file is written to
binary output, and backspaced over. The format of the statement Is:

SAVPAK n

where n is the disc pack number and the default n is pack one.

6-3.11 SAVUSR Statement

The SAVUSR statement saves all of a user' s files on all packs to the binary output
device. The files are saved in alphabetical order and in the same format as the SAVE statement.
The name and other information is output to list output device as each file Is saved. Upon com-
pletion of the entire group save, an end-of-file is written to binary output and backspaced over.
This assures proper termination of the data. The format of the statement is:

SAVUSR Unnn

SAVUSR nnn

where nnn is the user number specification.

6-3. 12 LIST Statement

The LIST statement is used to list and verify previously saved files. The binary
input logical file is scanned and infomiation pertaining to each saved file Is listed on the ll$t
output device. If a data checksum error is detected, a warning message Is output, and the
remainder of the files data records will be skipped. If a checksum error Is detected In the header
record after three retries, a fatal message is output and the job is aborted. The format of the
statement Is defined as:

LIST

No parameters are required.

6-3. 13 RESTORE Statement

The RESTORE statement is utilized to restore a disc file that has been previously
saved and deleted. The binary input logical device ( Logical File 04) Is searched from the current
position, bypassing other "SAVE" format modules, until the file with the specified name and
password is located. The file definition information Is then obtained from the header record,
and the file is re -defined in the directory and the appropriate disc space is allocated. The data

6-15

Revision C
November 1975

is then copied onto the disc. It should be noted that when a file is restored, it is allocated
the same quantity of disc space that it originally occupied, but not necessarily the same
physical area. The format for this statement is as follows:

RESTORE name, password, pack***, sector, newname, newpass

name- defined as in CREATE statement

f)assword

sector

pack"-

newname defined as in SAVE statement

newpass-

6-3. 14 RESPAK Statement

The RESPAK statement enables all files previously save to be recreated on the disc.
The binary input device starts from its current position and reads the next "SAVf:" header record
for file name and password. The file will be recreated automatically and data copied into the
disc area. If the file name is already used, a message is output to the list output device and the
file is skipped. This sequence repeats until an end-of-file is detected while attempting to read
a header record. Pertinent infomnation is output as each file is restored. The statement is defined
as follows:

RESPAK n,m

where n is the pack number from which the files were saved.

m is the pack where the files will be restored to. If not specified,

n is assumed.

6-3. 15 RESUSR Statement

The RESUSR is similar to the RESPAK statement. Binary input device is scanned for
all files saved with the specified user number. Upon finding a match, the file will be restored
if not already present. The statement is defined as follows:

RESUSR Unnn, pack*

or
RESUSR nnn, pack#

where the nnn is the user number specification.

pack* is an optional parameter which defines the disc pack to which the files are
to be restored. If the parameter is not present, then the pack number from which the SAVUSR was
generated is used.

6-3. 16 SAVMDD Statement

The SAVMDD statement saves the Master Disc Directory entries for all disc files
on all packs other than the master pack(pack 1), onto the binary output logical device. The
entries are saved in n2-word blocks plus a checksum word. The last block is filled with zeros
following the last saved entry. The format of the statement is:

SAVMDD

and no parameters are required.

6-16

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6-3. 17

REPSYS Statement

The REPSYS statement is used to replace the resident DMS on disc without going
through the original DMS generation procedure of initializing the entire disc and restoring the
various DMS files.

During the REPSYS procedure, several holds occur. Each must be released with the
OPCOM command /RB.

Logical files 4 and 5 are dynamically assigned during the copy process. Each rejad
or write will be exactly 1 sector or 1 12 words.

the format of the command is defined as follows:

REPSYS ffffff, tttttt

ffffff is the file name containing the new DMS system catalogued as TYPE=SYSGEN.
If the parameter is missing, the file name ' DMS' is assumed.

tttttt is an output file name or physical device number where the current DMS
( ' D. M. S. ' ) will be copied to. If no parameter is given, W2 is assumed.

The generation of a second copy of the current DMS allows recovery if the new
DMS does not function properly.

The following is an example of a REPSYS from a file ' NEWDMS'.

$JOB

generation of SYSDAT)

Inclusion of DMS modules)

Inclusion of OPCOM modules)

$C ATA LOG
DNAME=NEWDMS„R
TYPE=SYSGEN
BEGIN

(Cataloging of OPCOM)

6-17

Revision C
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SFILEMA

REPSYS NEWDMS

FILEMA: "REPLACE DMS? (OP message & hold)

FILEMA: COPY TO W2 ( OP message & hold)

FILEMA: COPY FROM NEWDMS ( OP message & hold)

FILEMA: DMS REPLACED (OP message)

RENAME OPCOM, OPX, GORP, GORP
RENAME OPCOMl, OPXl, GORP, GORP
RENAME OPCOM2, OPX2, GORP, GORP
RENAME OPCOM3, OPX3, GORP, GORP
RENAME OPCOM4, OPX4, GORP, GORP
RENAME OPCOM5, OPX5, GORP, GORP
RENAME OPC, OPCOM, GORP, GORP
RENAME OPCl, OPCOMl, GORP, GORP
RENAME OPC2, OPCOM2, GORP, GORP
RENAME OPC3, OPCOM3, GORP, GORP
RENAME OPC4, OPCOM4, GORP, GORP
RENAME OPC5, OPCOM5, GORP, GORP
$EOJ

Error messages associated with the REPSYS command are listed in Table 6-1.

6-3.18 CLEAR Statement

The CLEAR statement is used to initialize a new disc pack on multi-drive DMS
configurations. It has no meaning and cannot be used single disc systems. The format of the
CLEAR statement is as follows:

CLEAR pack*, disc*

where: pack* is the pack ID number (2-255) of the pack being initialized and
disc* is the disc number (2-64) on which the pack is now mounted.

The message

FILEMA CLEAR
PK* XXX DSC *yyy?

is output to the operator to allow verification of the input parameters. If valid, a
release background command must be given. If invalid, background should be aborted. When
released, the specified pack in initialized and all MDD entries giving reference to that pock are
removed. When the initialization is completed, the message

PACK CLEARED
is output.

A-lfi

Revision C
November 1975

6-3. 19 ZEROPK Stafement

The ZEROPK shatement is used to initialize a new disc pack on multi -drive DMS
configurations. It has no meaning and cannot be used on single disc systems. The ZEROPK
statement first performs a CLEAR (see section 6-3. 14) and then writes zeros in every sector of
the pack from sector 4 to the end. The number of sectors zeroed per write operation is dependent
upon background size, the disc being zeroed fastest when background size is large. The format
of the ZEROPK statement is as follows:

ZEROPK pack#, disc#

where pack* and disc*^ are defined as in section 6-3. 14 (CLEAR statement)

the message:

i-ILEMA ZERO

PK# XXX DSC^y/v?

is output tc the operator to allow verification of the input parameters. If valid, a
release background command must be given. If invalid, background should be aborted. When
the pack is completely zeroec, ihe following message ii ouroutt i

PACK ZEROED

6-3.20 READPK Stcfomsnt

The READPK statement is used to read a complete disc pack to find any sectors which
are unreadable. When a sector is found which cannot be read, information is output describing
the read attempt, the number of v/ords received and the sector which caused the error. The regds
then continue with the sector following the bad one. The Formot of the READPK statement is as
follows:

READPK pack*^, wordcount

where: pack* is the pack ID number (2-255) of the pack to be read.

and: wordcount is the number of words to be read per read operation.

This parameter is optional and if not supplied, the wordcount will be determined
by the size of bcckground.

6-3.21 FLAGPK Statement

The FLAGPK stotement is used to create permanent files over any sectors on a di$c
pack which cannot be read. The FLAGPK statement functions identically to the READPK statement
(section 6-3. 14B), but it automatically creates permaner^t type files over the sectors determined
to be bad. The file names are dynamically generated and are of the form Z'^NNNN with a
password of B. S. . The format of the FLAGPK statement Is as follows:

FLAGPK pack*, wordcount

where pack* and wordcount are defined as in section 6-3. 14B ( READPK statement).

If a file cannot be created over a bad sector (if another file already Included that
sector for example), a message will be output to that effect. If a file is successfully created
the file name created will be output.

6-18A. 1

Revision C
November 1975

6-3.22 ADVANCE Stafement

The ADVANCE statement is used to position the binary input logical file in front of
the next SAVE header record. No data error checking is perfonned. The statement is defined
as follows:

ADVANCE

No parameters are required.

6-3.23 REV/ Statement

The REW statement perfonn a rewind function on the specified logical file number.
The statement is defined as follows:

REW n

where n is the logical file specifications.

6-3. 24 WEF Statement

The WEF statement will write an end-of-file on the specified logical file number.
The statement is defined as follows:

WEF n

where n is the logical file number specification.

6-3.25 ADF Statement

The ADF statement will advance the specified logical file number to after the next
end-of-file. The statement is defined as:

ADF n

where n is the logical file number specification

6-3.26 BSF Statement

The BSF statement will backspace the specified logical file number to before the
previous end-of-fiie. The statement is defined as follows:

BSF n

where n is the logical file number specification.

6-3.27 HOLD Statement

The HOLD statement outputs a 15 character message to the OPCOM terminal and
then suspends background. The statement is defined as follows:

HOLD MESSAGE TEXTl I ; :

where "MESSAGE TEXT 1 1 1 " is the message to be output. Note that the format
assumes two blank characters between HOLD and the message text. This command requires an
OPCOM "/RB" to continue.

L ID A n

Revision C
November 1975

6-3.28

6-3.29

WORD

EXIT Si-atement

The execution of the file Manager is ferminated by the statement:

EXIT

SAVE/RESTORE Formats

The following is the SAVE/RESTORE format:

SAVE/RESTORE HEADER

FIRST THREE ASCII CHAR OF FILE NAME

SECOND THREE ASCII CHAR OF FILE NAME

23 22

P R

I P

V R

T O

P
R
O

20
D

P
R
O

19-0
RECORD WORD COUNT
ZERO= 113

FILE SIZE IN SECTORS

23 22
B S
L P
O O
C O
K L

20 19-16

E TYPE

15-0
MEMORY REQUIREMENTS

23-16
PACK NO

15-0
ABSOLUTE PROGRAM ORIGIN |

FIRST THREE ASCII CHAR OF PASSWORD

23-16
4TH CHAR OF PASS

15-0
USER NUMBER

CHECKSUM = -

(SUMMATION OF WORDS 0-7)

6-18A. 3

Revision C
November 1975

WORDS

0-ni

112-223
224-335

DATA RECORD LAYOUT

DATA FOR SECTOR ONE

DATA FOR SECTOR TWO

DATA FOR SECTOR THREE

784-895
896
897
6-3.30

DATA FOR SECTOR EIGHT

23 22 21 20 19 18 17 16
SEC#1 2 3 4 5 6 7 8
BIT SET = EOF SECTOR

15-0
NOT USED

CHECKSUM = -(SUM/V\ATlON OF WORDS 0-896

ERROR MESSAGES

Error checking is performed on file system functions to safeguard the integrity of the
disc. When an error is detected, an error message is printed on the program' s list output device
and the current job is aborted. The error messages and their complete definitions are listed in
Table 6-1.

Table 6-1
Error Message Definitions

Message

CORE NOT AVAIL
DISC* ERROR
DISC READ ERROR

DISC WRITE ERROR

FILE NAME ERROR

FILE NAME USED

Error Condition

A checksum error has been encountered from the binary
input logical device.*

A disc number was specified that was above the maximum
for this configuration.

A disc failure was detected following a read operation
involving the Master Disc Directory or a space
allocation map.

A disc failure was detected following a write operation
involving the Master Disc Directory or a space alloca-
tion map.

The file name from a RESTORE statement does not match
the one contained in a header record. This message is
also used when any file name specification does not start
with an alphabetic character.

The file name specified for a CREATE or RESTORE function
is already in the directory. **

Revision C
November 1975

Table 6-] (Cent)
Error Message DefiniHons

Message

FILE NON-EXIST
FILE NOT THERE
FILE SIZE ERROR
FILE TYPE ERROR
INVAL FUNCTION

PACK* ERROR

ABS BIAS ERROR

DMS NOT ON FIL£

INVALID PDN

DMS REPLACE
FATAL CKSUM ERROR

ALLOC SEC # ERR

NEW DMS INVALID

REPLACE DMS?

COPY TO:

COPY FROM:

PACK ZEROED
INVALID LFN

ERROR IN USER#

iiTnr Condition

The user a«-tempted to delete a file which is not defined in
the Master Disc Directory.**

The user attempted tc ^,ave a file which was not present
in the Master Disc Director. **

A zero-negative or nosi-numeric file size parameter was
specified.

A file-type parameter was specified incorrectly on a
CREATE statement.

A directive statement was encountered with a function
other than CREATE, DEIfTE, SAVE, RESTORE, DMAP,
EXIT, CLEAR, REPSYS, SAVEP, SAVPAK, SAVMDD or
DMAPS.

The pack number requested was not between 1 and 255
inclusive. Or was not specified when more than one
drive is available.

An illegal (negative) value was detected in a Dump
statement.

The file name containing the new DMS for the REPSYS
command is not available.

The output device specification for a REPSYS does not
exist.

The REPSYS command has successfully been completed.

Three unsuccessful attempts have been made to read a
SAVE/RESTORE record.

An invalid 'start of allocation' sector number has been
detected in the Create statement.

The file conJalning the new DMS is incorrect during
the REPSYS command.

Message to signify that a request is being made to over
write the disc resident DMS. *

The back up copy of the disc resident DMS is about to
begin. '

The new DMS Is ready to be copied onto the current disc
resident DMS. *

The pack has been successfully cleared

Only LFN's 4 & 5 are allowed on REW, ADV, BSF, WEF,
commands.

An invalid user number has been detected.

6-18A. 5

Revision C
November 1975

Message

EOT DETECTED

MDD SECTOR FULL

FILE IN USE

PASSWORD ERROR

FORMAT ERROR

MEM REG ERROR

REL ORG ERROR

LF ASSIGN ERROR

DMS TOO lARGE

Table 6-1 (Cont)
Error Messages Definitions

Error Condition

The end-of-output-area has been detected during a
SAVE too disc file.

The Master Disc Directory sector to which a specified
file has been assigned by the CREATE routine is-aiready
full. The user must either change file name such
that it will be assigned to another sector, or delete
files such that the required sector is no longer full.

An attempt was made to delete a file which was in
use by another program.

The user attempted to save or delete a file with an
incorrect password specified.

A request has been made supplying an improper sequence
of parameters.

The size of a program to be dumped was found to be
greater than the allocated background area.

An illegal (negative) value was detected in a DUMP
command.

An assignment to a device rather than a file was made
prior to an Establish command.

The DMS being replaced with a REPSYS command is too
large to be written in the disc space where DMS currently
resides.

* This command requires an OPCOM" /RB" to continue.
** This command generates a non-fatal error.

(S-1RA 6

Revision C
November 1975

6-4 LINKCATALOGER

The DMS Link Cataloger is a restricted background processor that is supplied with
DMS. Its purpose is to link separately assembled and compiled program modules, subprogram
modules, and library routines. During the linking process, common addresses are assigned,
externals and external equivalence requests are satisfied, and stringing is performed. The
resulting output of the linking processes is a complete program module, that is stored in a format
that enables the program to be quickly relocated in memory by the DMS loader prior to program
execution.

The Link Cataloger provides several methods of generating and executing a program
that is too large for available core. One of these methods is through the use of CHAIN segments.
A program that can be broken into several independent parts may use this method. Each part is
cataloged as a distinct program, called a CHAIN segment. All data that is transferred between
CHAIN segments is passed through logical files or fhrough common. The Link Cataloger has
provisions to enable all of these CHAIN segments to share the same common area. Each program
unit (or CHAIN segment) is executed separately, and when complete, it passes control to the
next CHAIN segment by use of the System Service CHAIN (see Paragraph 4-7) or by use of the
FORTRAN CALL CHAIN.

Another method of conserving core is through the use of overlays. This method is
often called segmenting, but should not be confused with CHAIN segments. An overlay program
is made up of several overlay segments and a main segment which is always in core and is known
as the root. Each overlay segment contains one or more subprograms. These segments are loaded
into core only when a reference is made tc one of ths subprograms contained within the segment.
Thus, one or more of these segments may be loaded into the same area of core. The only
restriction being that the two segments may not be needed at the same time (i. e. , they muy not
call each other).

6-4. 1 Overlay Type Programs

An overlay type program consists of a main segment (called a root) which Is
permanently core resident during execution and one or more additional segments which are
loaded into core by a FLIPER routine when they are needed. The FLIPER routine is part of the
root. This routine is automatically Included into an overlay program.

The structure of an overlay program is determined by the layout of overlay areas
within the total program area. The simplest meaningful example consists of a main program
which calls two subprograms. This example is indicated by the following diagram.

6-)8A.7

LOW
CORE

HIGH
CORE

MAIN PROGRAM

FLIPER

ROOT

OVERLAY AREA

Figure 6-1. Overlay Program

In this example, the main program contains calls to each of the subprograms A and B.
The root of this program consists of the main program and the FLIPER routine. There are two
segments which may be called A and B. Segment A consists of subprogram A and segment B con-
sists of subprogram B. Note that segments A and B share the same area of core. This area Is
known as an overlay area. In this example It is assumed that segment A does not fill up the
entire overlay area. It is normally true that all segments that share an overlay area are not thje
same length. Because of this, the length of an overlay area Is determined by the length of the
longest segment that Is to be loaded into the area.

The main program In this example defines the base address for the overlay area.
Because of this, all segments in the overlay area are known as children of the main program.
And correspondingly, the main program is known as a parent of each of its children.

A program may consist of more than one overlay area. When more than one overloy
area exists, each area Is identified by a phase number. Phase zero is that overlay area closest
to the parent segment. Phase one is the next overlay area; it resides just above phase zero In core.
Phase two Is the next area, etc. The following diagram is an example of a three phase overlay
program.

6-19

MAIN PROGRAM

FLIPER

}

ROOT

- PHASE j2f

PHASE 1

PHASE 2

Figure 6-2. MulH -Phase Overlay Program

In this example, all of the segments A, B, C, D, E, and F are referred fo as children
of the root. Because of this multiphase structure, It is possible for more than one segment to be
present in core at one time. For example, the segments A, D and E may all be present at one
time. Therefore, it is also possible for each of these segments to reference another segment not
on the same phase level. It Is not possible for segments on the same phase level to reference each
other. Care should be taken that this Is not attempted. If such a reference Is done indirectly,
(I.e., A calls E, which calls B) the results are undefined.

In addition to multiphase overlays. It is also possible for a single segment to be
broken up Into several overlays. This Is referred to as multilevel overlays. This Is illustrated
by the following example.

6-20

PHASE i3f
OF A

MAIN PROGRAM

FLIPER

'SWmmiM

}

ROOT

PHASE i3f
OF B

PHASE j3^
OF ROOT

Figure 6-3, Multi -Level Overlay Program

In this example, there is one overlay area associated with the root, this overlay area
extends from the initial location of segment A to the final location of segment C. This means
that all of the segments (A, B, C, D, E, F, G, and H) are children of the root, and they are all
in phase zero of the root. There is also one overlay area associated with segment A, This
overlay area is phase zero of segment A and extends from the first location of segment C to the
final location of segment C. Similarly, phase zero of segment B extends from the first location
of segment G to the last location of segment G. Note, that the definition of phase zero of the
root includes segments A and B and all of the phases of A and B. Segments C, D and E are
children of both A (since they are in a phase of segment A) and the root (since they are in a
phase of the root).

References between parents and children are allowed. References between two
segments that are not related as parent and child are allowed only if the two segments are in
different phases of the same parent segment. Thus in the above example, segments F and G may
not reference each other, segments C, D and E may not reference each other, and none of the
segments A, C, D, or E may reference or be referenced by any of the segments B, F or G.

These two structures, multi -phase and multi -level overlays, may be continued to
any desired extent. They are limited only by available core. The following example is pre-
sented as a possible structure available through the Link Cataloger. It is presented without
explanation only to demonstrate the possible complexity of structure that can be obtained.

6-21

MAIN PROGRAM

FLIPER

WmlWmi

ilBiltaiii

WmMMifimi

||||||ii|:'ii|ii;iilil:||||||i

iiili^isiiisiiiiii^iiiilliiiiisiiii;::^^^

;:':::::::';::-:'x;:':ox;:':;:;>:;;;:i;i:;;;W:xx;?o^^

iiiiiiililiiiiliiiiiiiiiiiiiiii^^^^

wmmm;m

\A/

1;" ,' ■

:;::.::::S::;;::;:s.;.::::i:;;S: ■::■:::;;:::::::};;:

WM'SiMh

6-4.2

Figure 6-4. MulM-Phase, MulH-Level Overlay Pfogram

Link Cataloger Control Statements

The Link Cataloger is activated In the background area by Issuing one of the
following Job Control Statements.

SCATALOG
$CATGO

6-22

Revision B
March, 1975

When activated by the $ CATALOG Job Control Statement, a series of input requests
are made from the Job Control logical device for a set of control statements. Each control
statement is output to the list output logical device unless both Job Control and List Output are
assigned to physical device one. These control statements describe the various parameters to be
associated with the program to be link cataloged and the condition under which the link process
is to take place.

The various control statements, their format, and meanings are discussed in the
following paragraphs.

TYPE

The TYPE control statement has the following format:

BG
TYPE = FG, PRIV, SAUT, OA, OM, UA, UM, lOA, SEGMNT, LM, DICT, SYSGEN
RFG STOICT NSAUT NOA NOM NUA NUM NIOA
RENFG

The meanings of the various parameters are as follows.

a. BG Specifies that the program to be cataloged is to be typed as a

background program.

b. FG Specifies that the program to be cataloged is to be typed as a

foreground program.

c. RFG Specifies that the program to be cataloged is to be typed as a

resident foreground program.

d. RENFG Specifies that the program to be cataloged is to be typed as a

re-entrant foreground program.

e. PRIV Specifies that the program is to be run in a privileged mode at

execution time. (Bits 23 of P/MODE of PSA is set to one. ) **

f. STRICT Specifies that the program is to be run in a restricted mode at

execution time. (Bits 23 of P/MODE of PSA is set to zero. ) **

g. SAUT Specifies that the program is to be executed with the SAD executive

interrupt trap enabled. (Bits 22 of P/MODE in PSA is set to zeroi. )*

h. NSAUT Specifies that the program is to be executed with theSAU executive

interrupt trap disabled. (Bits 22 of P/MODE in PSA is set to one. )*

i. OA Specifies that the program is to be aborted if an SAU overflow

occurs. (Bit 18 of P/MODE in PSA is set to zero. )*

j. NOA Specifies that the program is not to be aborted if an SAU overflow

occurs. (Bit 18 of P/MODE in PSA is set to one. )*

k. OM Specifies that a message is to be output to the operator communica-

tions device if an SAU overflow occurs. (Bit 19 of P/MODE in
PSA is set to zero. )*

'Refer to Paragraph 4-18.2

6-23

Revision B
March, 1975

NOM

m. UA

n. NUA

o. UM

p. NUM

q. lOA

r. NIOA

SEGMNT

Specifies that no message is to be output if an SAU overflow occurs.
(Bit 19 of P/MODE in PSA is set to one. )*

Specifies that the program is to be aborted If an SAU underflow occurs.
(Bit 20 of P/MODE in PSA is set to zero. )*

Specifies that the proaram is not to be aborted if an SAU underflow
occurs. (Bit 20 of P/MODE in PSA is set to one. )*

Specifies that a message Is to be output to the operator communications
device if an SAU underflow occurs. (Bit 21 of P/MODE in PSA is
set to zero. )*

Specifies that no message is to be output if an SAU underflow occurs.
(Bit 21 of P/MODE in PSA is set to one. )*

Specifies that the program is to be aborted if an I/O error occurs.
(Bit 17 of P/MODE in PSA is set to zero. )*

Specifies that the program is not to be aborted is an I/O error
occurs. (Bit 17 of P/MODE in PSA is set to one. )*

Specifies that the program being cataloged is a program CHAIN
segment.

Specifies that the program being cataloged is a "large" module"
to be dumped relative to some other location than background low
and therefore the check for crossing the map boundary is to be
disabled.

DICT

:)GEN

Specifies that the cataloged program is to be typed such that its
Master Disc Directory entry is to be loaded in the core resident
directory table. Refer to Paragraph 3-5. 3.

Specifies that the two header words normally output by the cataloging
process are not to be produced. The resulting module contains the
first program word as the first word on disc. This parameter is
normally used only in the System Generation procedure to produce
the DMS load module. Any other situation should not use this
parameter unless a special circumstance warrants its use.

NONACC Specifies that the foreground program being cataloged is not to

generate accounting records when executing. If the program is a
background program, this specification is Ignored. (Bit 16 of
P/MODE in PSA is set to one. )

* Refer to Paragraph 4-18.4

All of the preceding parameters are optional and may be specified in any order within
the statement. If any of the parameters are omitted, then the default values which are established
are as if the following TYPE control statement were issued.

TYPE = BG,STRICT,SAUT,OA,OM,UA,UM,AFER

The equal sign (=) in the format given above is optional any may be replaced with a
blank.

6-24

Revision A
May, 1974

Any number of TYPE control statements may be given. If any of the program type or
mode parameters ore respecified, either within the same statement or on saporate statements, then
the last encountered specification will be used.

NAM E

The t^lAME control statement has the follov/ing format:

NAME = XXXXXX,p,R, W, D

The XXXXXX specification is a one to six characters program name that must begin with
an alphabetic character and must not contain an equal sign (=), comma (,), or blank. Issuing a
NAME control statement indicates that a permanent file is to be created with the name XXXXXX.
If no NAME control statement is received, then the output of the Link Cataloger will reside on
the Go File ('16). The p specification is an optional parameter that specifies the pack number
on which the program is to be permanently cataloged.

If an "R", "W", or "D" is entered as an additional parameter, then the corresponding
read, write, or delete access bits are entered in the file directory entry. These access bits are
useful only in accounting systems. See Section III. More than one of these bits may be specified.
If no access bits are specified, then the program can only be referenced by Its creator,

NOTE

If the program Is an overlay program, then both
"R" and "W" access bits must be set in order for
the program to be executed by other than Its
creator.

DNAME

The DNAME control statement Is Identical In format and function with the NAME
statement with the following difference. Immediately before creating a permanent program file,
the specified name Is used to delete the previous version of the program. The previous version
of the program Is not deleted (and a new program is not created) If any cataloger errors occur
during the cataloging process. If the previous program does not exist or If the program Is not
accessible by the current user, then the message, FILE NON-EXIST, will appear on the list -output
device. In either case, the cataloger will attempt to create a permanent file. If the program
file cannot be created due to a conflict with another user's program, then the message, FILE
NAME USED, will appear on the list-output device and the job will abort. Otherwise, the
catalog process will run to completion.

ASSIGN

The ASSIGN control statement has the following format;

ASSIGN xp=y,xp=y,xp-*y (s)

The X parameter is an octal logical device number which is assigned to file name y
or physical device y, or spooled device y. In the case of spooled assignments, the file size may
optionally be specified. (See Section 6-2. 3). The p specification follov/Ing the logical device

6-25

Revision C
November 1975

number is optional and, if present, indicates that the assignment is to be permanent and therefore
cannot be changed by program or operator action. A comma G) may be substituted for the equal
sign (-) in the above format.

The Link Cataloger accepts ASSIGN control statements only if the program type has
been previously specified as a resident or standard foreground Pfogr°m via a TYPE control state-
ment. Assignments for background programs must be made via the $ASSIGN Job Control state-
ment. (See Paragraph 6-2. 3). Assignments for re-entrant foreground programs must be made
through the system service ASSIGN. (See Paragraph 4-13).

Any number of ASSIGN statements may be issued and any number of assignments may
be made on any given statement. However, once an assignment has been made for a logical
device number, another assignment referencing that same logical device number may not be made.

OPTION

The OPTION control statement has the following format:
OPTION=N

where N may be anyone or more (separated by commas) of the options 16, 17, 18, 20, 22 or 23.
The equal sign (=) in the format given above is optional and may be replaced with a blank.

Through the use of this statement, options may be cataloged with a program. In the
execution of foreground programs, the options used at execution timeare those which were
cataloged with the program and all others are zeroed. In the execution of background programs,
the options used at execution time consist of the logical "OR" of the current background option
word and the options which were cataloged with the program.

The usage of OPTION settings by standard DMS routines and processors is given In
Appendix D.

6-26

RevisiQn C
November 1975

NOMAP

The NOMAP control sfafemenf specifies that an external table listing is not to be
output at the completion of the linking process.

CBASE

The CBASE control statement has the following format.
CBASE =x

The X specification of the statement is an octal address of a common base specifica-
tion. A blank may be substituted for the equal sign in the above format. Refer to Paragraphs
6-4. 9 and 6-4. 10 for usage of this statement.

LIBRARY

The LIBRARY control statement has the following format.

LIBRARY=XXXXXX,YYYYYY,ZZZZZZ

The XXXXXX, YYYYYY and ZZZZZZ specifications are library file names. If the
library file specified has a password, then the password should follow the file name in parentheses
(e.g., CAT(DOG)). When this statement is encountered, any previously encountered library
specifications are lost and the new library list is stored as the current library list. If no LIBRARY
statement is used, then the current library list consists of the file to which LFN 12 is assigned
during the cataloging process.

During the cataloging process, each library is processed in order according to the
order of their specification on the LIBRARY control statement. Each library is processed
completely until no more undefined externals can be satisfied, before the next library is processed.

The word LIBRARY may be abbreviated to LIB and the equal sign may be replaced
by a blank in the above format.

NOLIB

The NOLIB control statement specifies that the current library list is not to be ^
scanned to find undefined externals for the program being cataloged. When this statement is
used for an overlay program, the statement refers only to the segment currently being defined.

This statement would normally be used to save catalog time when it is known that
the undefined externals will not be satisfied during the library processing.

INCLUDE

The INCLUDE control statement has the following format.
INCLUDE=XXXXXX,AAAAAA,BBBBBB,CCCCCC

6 -26 A

The XXXXXX specification is an include file name. If fhe include file specified
has a password, then the password should follow the file name in parentheses (e. g. , CAT(DOG)).
The AAAAAA, BBBBBB and CCCCCC specifications are module Identifiers. These identifiers may
be external definitions or names (i.e., generated by NAME statements In FORTRAN or Assembly
Language). If it Is desired to specifically allow only an external definition or a name, then the
specification should be preceeded by a dollar sign ($) or a period (. ), Identifying an external
definition or name respectively.

The function of this statement is to cause the Inclusion of the specified modules
from the Include file into the program being catalogued. If no module names are specified,
then the entire file is included; in this case, the INCLUDE control statement functions similar
to the Job Control Statement $INCLUDE.

If the program being catalogued is an overlay program, then the module or modules
specified are included only In the segment currently being defined.

The word INCLUDE may be abbreviated to INC and the equal sign may be replaced
by a blank in the above format.

MODULE

The MODULE control statement has the following format.

MODULE=AAAAAA,BBBBBB,CCCCCC . . .

The AAAAAA, BBBBBB and CCCCCC specifications ore module Identifiers, These
identifiers may be external definitions or names and should be specified similarly to the identifiers
on the INCLUDE control statement.

The function of this statement is to identify selected modules from the Link Ready File
(LFN 15). When this statement is used, the normal Link Ready processing is modified. Normally
all modules in the Link Ready File are Included in the program; however, when this statement is
used, only those modules specified will be Included In the program being catalogued.

If the program being catalogued is an overlay program, then the module or modules
specified are included only In the segment currently being defined. If this statement is not used
during the definition of the main segment (or root), then the root will contain all modules from
the Link Ready File that are not specified as part of a segment.

The word MODULE may be abbreviated to MOD and the equal sign may be replaced
by a blank in the above format.

SEGMENT

The SEGMENT control statement has the following format.

SEGMENT-AAAAAA,BBBBBB,CCCCCC

This statement defines a specific segment in an overlay program. If this is the first
SEGMENT statement, then it also defines the program to be an overlay type program. This
statement terminates specifications for the previous segment. The library list that Is

6-27

current when this statement is encountered is used for the previous segment (unless a NOLIB
control statement was entered for that segment). If this is the first SEGMENT control statement,
then the previous specifications refer to the main segment (or root).

Each segment must contain within its defining specifications at least one MODULE
or INCLUDE control statement. This does not apply to the main segment (or root) since the
absence of a MODULE control statement for the main segment implies that all unspecified
modules in the Link Ready File are to be included in that segment.

The AAAAAA specification is used as the segment name. This specification is
optional. If it is omitted, then the segment name will appear as blanks on the output listing and
the segment may not be referenced in another SEGMENT control statement.

The BBBBBB specification is the name of the parent segment being defined. If this
specification is omitted, then the parent segment is assumed to be the main segment or root.
The main segment may also be identified explicitly by ROOT. Except for ROOT, BBBBBB rnust
have already been Identified on a previous SEGMENT control statement. The BBBBBB speci-
fication may also be optionally proceeded by one or more asterisks (*). The number of asterisks
indicate the phase level of the segment. None Indicates phase zero, one asterisk indicates phase
one, etc. If the parent segment is the main segment, the BBBBBB specification may consist of just
one or more asterisks.

The CCCCCC specification is the overlay type of the segment. CCCCCC may b$
omitted or It may be one of the following words: STNDRD, NEW or UPDATE. If CCCCCC is;
omitted, it is assumed to be STNDRD. The overlay type of the segment defines the loading artd
unloading procedures for the segment. For more explanation, see Paragraph 6-4,5.

The word SEGMENT may be abbreviated to SEG and the equal sign may be replaced
by a blank In the above format.

Figures 6-5, 6-6, 6-7 and 6-8 shown examples of the use of the SEGMENT control
statement to define several overlay structures. These structures are the same structures that
were shown in Figures 6-1, 6-2, 6-3 and 6-4.

NOTE

The assumption is made that each segment con-
tains only one module. This module is present on
the Link Ready File and has the same name as
the segment.

6-28

$CATALOG
SEGMENT A
MODULE A
SEGMENT B
MODULE B
BEGIN

LOW
CORE

HIGH
CORE

MAIN PROGRAM

FLIPER

- ROOT

- OVERLAY AREA

Figure 6-5, Overlay Program - Control Stafements

6-29

'^^CATALOG
SEGMENT A
MODULE A
SEGMENTS
MODULE B
SEGMENT C/
MODULE C
SEGMENT D,*
MODULE D
SEGMENT E,**
MODULE E
SEGMENT F,**
MODULE F
BEGIN

MAIN PROGRAM

FLIPER

./ [. ' \ . ; • :

}

ROOT

PHASER

PHASE

- PHASE 2

Figure 6-6. Multi -Phase Overlay Program -Control Statements

6-30

SCATALOG
SEGMENT A, ROOT
MODULE A
SEGMENT B,ROOT
MODULE B
SEGMENT C,A
MODULE C
SEGMENT D,A
MODULE D
SEGMENT E,A
MODULE E
SEGMENT F,B
MODULE F
SEGMENT G,B
MODULE G
BEGIN

PHASE
OF A

MAIN PROGRAM

FLIPER

Wiiwm

:^>^^-^y-!i'::i<^i^-^^i

y ROOT

PHASE j2^
OF B

PHASE
OF ROOT

Figure 6-7. Multi-Level Overlay Program -Control Statements

6-31

SEG A

SEG I,G

SEGQ,*D

SEG X,*

SEG EE,**

SEG B,A

SEG J,*G

SEG R,Q

SEG Y/*

SEG FF,Z

SEG C,A

SEG K,*G

SEG S,Q

SEGZ,**

SEG GG,Z

SEG D

SEG L,*G

SEG T/

SEG AA,**

SEG HH/Z

SEG E,D

SEG M/*G

SEG U,T

SEG BB,AA

SEG 1I,*Z

SEG F,D

SEG N/*G

SEG V,T

SEG CCAA

SEG JJ,*Z

SEG G

SEG O/D

SEG W,T

SEG DD,**

SEG KK/Z

SEG H,G

SEG P/D

NOTE

Only the SEGMENT control statements were shown. The
appropriate MODULE or INCLUDE control statements would
need to be added to actually catalog this program.

MAIN PROGRAM

FLIPER

, I

BT. \ ^--T^

, N

.■ : ■■ "

:...:.;■ v;;:;;::;;;;:;:;:;^^^^^^^^^^^^

;:::::;:>:::::":":":;:::;:;:;:;x;:i io:;:;:;:;:;::;

9MMMimS

FF -

x^ii^^:

.::v:v:;:v:;;;;v'™!'l:-;';M!'!!:-:-x::;::::;;:;[;:;:y::

y^^^W^^^yy^:^^

WM'M^^t^i

WmBIISMmM

;^-;'x:;.-:-:-:'i''-:^'^>>:y-:o,v:^':-:-:-:---;--':':>:

fJ-WvS;:

"—

f*:;;;:;:;;';;;;;-:;

■MiiiM

.■; ^iyiim

Figure 6-8. Multi-Phase, Multi-Level Overlay Program -Control Statements

6-32

Revision B
March, 1975

FLIPER

The FLIPER control statement is useful only during the cataloging of an overlay program..
It may appear anywhere before the BEGIN control statement In the absence of this statement,
the only external references between segments are through the following instructions: BLL, B5L,
BLI, BU, and BLK. The exception is from child to parent, since this external reference will
never require the loading of a segment. If the FLIPER control statement is used, then all
references between segments are allowed, and the assumption is made that the user has made
allowances for non-standard external references.

RESTRT

The RESTRT control statement is a special purpose statement designed for system gener-
ations. Its effect is to cause the link cataloger to input additional control Pffmeters and restart
the cataloging process at the completion of the cataloging of the current module. When this
restart is performed, the logical file 15 position is not changed and all previously encountered
external definitions and external equivalence values are saved to be available to the next
module The effect Is to allow more than one program to reference the same set of external
definitions and equivalences. The programs to be cataloged via this process must all be on
logical file 15; separated only by a single end-of-flie mark between each program. Any number
of programs may be cataloged together via use of multiple RESTRT parameters.

BEGIN

The BEGIN control statement indicates that no more Link Cataloger control statements
follow and that the linking and cataloging process is to begin. This statement may be omitted
since the cataloging process will also begin on encountering an EOF on command input. (Reading
the next JOB CONTROL statement will return an EOF status and initiate cataloging. )

6 -4. 3 Link Cataloging Process

The link cataloging process consists of rewinding the Link Ready File (LFN 15) and
linking all programs and subprograms residing on this file until an End-of-File is encountered.
If unsatisfied externals remain, then the library file will be rewound and searched for the unsat-
isfied external requests. If, while passing through the library file, all requested externals are
satisfied, the linking process terminates and cataloging begins. If an End-of-File Is detected
on the library file when unsatisfied externals still exist than a determination Is made as to whether
or not at least one external was satisfied during the most recent pass over the library file. If at
least one external was satisfied, the library file is rewound and the process Is repeated. If no
externals were satisfied at the completion of a pass over the library file, then the second library
file (as specified on the LIBRARY control statement) Is processed In a similar manner. When the
last library has been similarly processed, the linking process terminates and the cataloging pro-
cedure begins. Any unsatisfied external requests are replaced by a BLU $ABORT.

An exception to this Is the external "PG::HI". If this external is referenced In the
module being cataloged and Is left undefined at the termination of library processlrjg; then the
program high location is used as the definition of $PG::HI. This location is the first location
beyond the entire program, Including common and overlay segments.

The cataloging procedure consists of determining whether a permanent or non-permanent
program file is to be created. If a NAME control statement was issued, then the output of the
link cataloger which resides on the System GO file (LFN 16) Is copied to a permanent file having
the name specified on the NAME control statement and a password of GORP. If a NAME control
statement was not issued, then the type and memory requirement specification of the System GO
File is redefined in order that the linked program may be loaded and executed when the Link
Cataloger relinquishes control of the system.

6-33

If the Link Cataloger is IniMated by the $CATGO (CATalog and GO) Job Control
statement, then the link cataloging process begins immediately as if the following control
statements were issued.

TYPE=BG,STRlCT,SAUT,OA,OM,UA,UM,AFER
BEGIN

Upon completing the link cataloging process, control will be passed to the System
Loader. The resultant load module which was produced by the Link Cataloger will then be
loaded and executed.

6 -4. 4 Link Cataloging Overlay Type Programs

The link cataloging process for overlay programs consists of several steps. The first
step consists of rewinding and processing all programs and subprograms on the Link Ready File
and on each of any specified Include files. In addition, the entire file FLIPER with the password
SYSTEM is included into the root; this file contains the FLIPER routine. The processing of each
module consists of determining which segment each module belongs to. If the module is part of
the main segment (or root), then it is linked immediately. If the module is part of an overlay
segment, then the module Is processed only to determine its length and any externals which are
referenced or defined within it. The length of the module is then added to a length counter for
the appropriate segment.

When all Include files have been processed, then the external table is examined to
find all undefined externals. If an undefined external is found, an attempt is made to define it
through a definition in another segment. If no definition is found or the reference between
segments is not legal, then the external is left undefined, with the assumption that it will be
defined within the library.

During the library processing, a determination Is again made as to which segment a
library module belongs. If a library module defines an unsatisfied external in two or more
segments, then this module will be included in each of the segments. If this Is not desired, then
the library should be explicitly included in the parent of these segments (see INCLUDE). Again,
only length and external information is obtained for modules that are within a segment.

When library processing Is complete, the main root module is finished up. Common
Is allocated and segment locations are allocated. A link map of the root is output if requested.

Then, each segment is cataloged separately. Each module within the segment Is
accessed randomly by a relative record address and the segment is cataloged. After each
segment, the link map for the segment is output if requested.

6-4.5 Execution of Overlay Type Programs

The program file of an overlay program consists of several relocatable absolute
modules. There Is one such module for each segment (root and overlay) In the program. In
addition, there is a reserved area for each overlay segment. This reserved area is used to save
a copy of the segment after it has been relocated so that on subsequent loads of the segment,
it can be reloaded without relocation and thus It can be reloaded faster.

6-34

When l-he program begins execution, logical file 77 is assigned to the program file.
This assignment must not be changed during execution of the overlay program, since the loading
and unloading of segments takes place through LFN 77.

The execution of an overlay program when an overlay is necessary takes place as
follows. When a reference is made from one segment to an external in another segment (which
Is not a parent), the address actually referenced is in the FLIPER table. This table is automa-
tically created by the Link Cataloger when it is determined that an overlay type program is
being catalogued. An entry exists in the FLIPER table for each external which is referenced
in another segment from that in which it is defined (except for child to parent references). This
entry appears as follows.

AAAAAA BSL SFLIP:!

DAC BBBBBB
DAC SEGMENT

AAAAAA is the external address that is actually referenced. BBBBBB is the actual
entry address of the routine, when the segment is loaded. FLIP:1 is an entry point in the FLIPER
routine that loads the segment. And SEGMENT is the address of an entry in the FLIPER table
that contains Information needed to load the segment. If AAAAAA Is referenced by a BSL
instruction, then the entry appears as follows. (FLIP:2 is the FLIPER routine entry point used to
process BSL calls. )

AAAAAA

BSL <^FL1P:2

DAC BBBBBB

DAC SEGMENT

When called, the FLIPER routine will load the segment in which the requested external
is defined. The FLIPER routine will also load all of the parents of the requested segment. If
any of these segments that are to be loaded are already present In core, then the load process
Is bypassed. If the segment Is not present, then all segments that are present and are partly or
wholly within the area to be overlaid will be unloaded. When this process is complete, all
registers (including the condition register) are restored, and the segment Is entered at the
actual external address requested. In the special case of a call by a BSL, the return address
and condition are stored at the actual external address requested; therefore, making the FLIPER
processing transparent to the segment.

In some special cases, it may be desirable to cause a segment to be loaded without
directly calling it. This function may be performed by the following calling sequence.

TLO SEGMENT
BSL SFLIP:3

This call will result In the loading of the specified segment, and all parents of the
specified segment. Because of this and other system requirements, the following list of externals
may not be used when cataloging an overlay program: FLIP:0, FLIP:1, FLIP:2, and FLIP:3.
FLIP:0 is the first location of the FLIPER table and is used by the FLIPER routine to enable
loading of all parents of a specified segment.

The actual process of loading and unloading a segment is dependent upon the type of
segment. In all cases, the initial load of a segment Is done through the System Loader. The
System Loader loads and relocates the segment into the appropriate overlay area. Subsequent
loads are done with a single read fiom the reserved area of the program file for Hie requested
segment.

6-35

For a STNDRD (see SEGMENT control statement) overlay segment, the first unload
request for the segment results in a single write of the segment to the reserved area of the
program file for the segment. Subsequent unload requests are ignored, and the segment status
is flagged so that following load requests cause the segment to be read in.

For a NEW (see SEGMENT control statement) overlay segment, the initial load of
the segment is immediately followed by an unload to the reserved area of the program file. All
standard unload requests result only in flagging the segment status so that the segment will be
read in when next requested. The distinction between NEW and STNDRD segments is that data
modified during the initial load of the segment will be re-initialized during a reload of a NEW
segment, and will remain in the modified state during all reloads of a STNDRD segment.

For an UPDATE (see SEGMENT control statement) overlay segment, each unload
request for the segment will result in a single write of the current segment to the reserved area
of the program file for the segment. Thus data modified during any execution of a segment
module will remain modified for the next reload. It should be noted, that for any significant
number of overlays, an UPDATE segment will result in approximately twice as many disc accesses
as a STNDRD or NEW segment.

6 -4. 6 Link Cataloger Output Format

As the linking process proceeds, an Internal buffer is used to accumulate the program
being processed. Whenever this buffer is filled, it is output to logical device 16 which must
have been assigned to a disc file. As each program word is placed in this buffer, a corresponding
relocation code is placed in the relocation vector array. This code specifies to the DMS system
loader whether the word is to be relocated or not, and if so, whether the relocation is to be
within a 15 or 16 bit address field (refer to Figure 6-9).

When all linking functions have been performed, the relocation vector array will be
output behind the program in fixed word length records consisting of 1 12 words.

For background programs the DMS System Loader reads the program into memory a$ a
single record. The relocation vectors are then read, sector by sector, and the program relocated.
Foreground programs are loaded with one disc access; the program body is read into the area
allocated for the program, and using the restart feature of the disc ABC channel, all of the
relocation vectors are read into a dynamic core buffer. After relocating the program the
dynamic core buffer is deallocated. The size of the program body read Into core Is the pro-
gram plus 2 additional words for background and re-entrant foreground progrcm and the program
plus 114 additional words for foreground programs. The relocation bias used by the DMS System
Loader will correspond to the address of the first word of the program minus 2 for 1 14 for back-
ground and foreground programs, respectively.

6-36

PROGRAM WORD 1

PROGRAM WORD 2

PROGRAM WORD 3

PROGRAM WORD 4

PROGRAM WORDS

PROGRAM WORD 6

PROGRAM WORD n-2

PROGRAM WORD n-1

PROGRAM WORD n

NOTES: RC=two-bi1- relocation code:

IF RCOO, then the corresponding program word is not to be relocated.

RC=01, then the corresponding program word is to be relocated In a 15-bit
address field.

RC=10, then the corresponding program word is to be relocated in a 16-bit
address field.

Figure 6-9. Link Cataloger Output Format

6-37

6-4.7 Link Cataloging Background Programs Accross the 32K Boundary

Provision is made in the Link Cataloger for automatically creating background load
modules that will cross the 32K memory partition. If during the linking process it is deterrrj.ned
that a subroutine will cross the 32 K boundary when loaded Toy the System Loader, then the Imk
cataloging process will be restarted for that subroutine. The restart procedure is such that the
subroutine will reside at '100000 when loaded. (Note that the Link Cataloger is able to
determine boundary crossing since all background programs are loaded at the same memory
location. ) When the final load module file is created by the Link Cataloger, the prograrn will
be typed as "ABSOLUTE BACKGROUND". The significant difference between non-absolute
and absolute background programs is that it will be necessary to re-cata og absolute background
programs if a new System Generation is performed. This is because the background low memory
address will generally change; therefore, the absolute address will not be valid under a new. _
system This checking is disabled by entering the "LM" option on the "TYPE" statement, aljowmg
the user to catalog large background programs and later dumping them for execution at another
address.

6 -4. 8 Link Cataloger Table and Buffer Allocation

In order to build the program and its associated relocation vector array on the System
GO File, it is necessary that the Link Cataloger be provided with working storage The entire
area between the end of the Link Cataloger (which is a background processor) and background
high is utilized. This available space is partitioned into two regions, one in which the program
or portion of the program is built, and the other where the external table and relocation veC^tor
array are built (refer to Figure 6-10). A determination of where this partition is to be located
in the available background area is made according to the following rules.

A An initial relocation vector array and external table area consisting of

2000 locations is assigned if at least 1 12 locations for the program work
buffer are available. If there are not 112 locations for the work buffer
when the table area Is 2000 locations, then a work buffer area of 112
locations is assigned and the remaining area Is assigned to the table region.

B. If during the Link Cataloging process. It is determined that the re-

location vector array is about to overlap the external table, then
the following occurs. The current work buffer is output to the
System GO File. The table area is increased by 1000 locations if
there will be at least 1 12 locations left for the work buffer, other-
wise the table area is set to the entire available area less 1 12
locations. Then appropriate Internal parameters are recalculated,
the external table is moved down to the new beginning location of
the table area, and the cataloging process continues.

The formula for determining the amount of storage required to contain the relocation
vector array is as follows.

Array Size = program size/12

The formula for determining the amount of storage required to contain the external
table is as follows.

6-38

External table size - 12+E+C+Q+I

where: E = (number of external entries. '' (overage size of entry (^4)))

C= (numbers of common block names)* 3+2 * (distinct number of common
variables)

Q= (number of external equivalence definitions) *4

I = (number of internal string requests) *2

The minimum size of the program w/ork buffer is 1 12 locations, however, the time
required for the link cataloging procedure will be considerably lessened if larger amounts of
storage are available.

FOREGROUND AREA

Vector ▼ Array
VECTOR ARRAY AND TABLE AREA

External T Table

WORK BUFFER TO
BUILD PROGRAM

LINK CATALOGER

RESIDENT SYSTEM

Physical Memory High

Background High

Background Low

Physical Memory Low

Figure 6-10. Link Cataloger Table and Buffer Allocation

6-39

6-4. 9 Common Memory Allocation

One of the design features of the Link Cotaloger is that the common region (which is
always assigned above the program) is automatically compressed to the first available location
following the user's program. This permits the Link Cotaloger to define (for the system Loader)
the smallest possible program memory requirements, since the common region is normally
considered as being part of the program. If however, a CBASE control statement has been
issued, then the start of the common region will be assigned to the relative address on the
control statement and be built upwards. The address on the CBASE control statement is always
relative to the actual program and is independent of the program type (background or fore-
ground).

In overlay type programs, the common is normally compressed to the first available
location following the main segment (or root) and all overlay segments. If however, a CBASE
control statement has been issued, then the start of the common region will be assigned to the
relative address on the control statement and be built upwards as for a non-overlay type program.
The segments will be allocated as much as possible between the program and the common area,
with the segment overlay areas which are too large allocated above the common area.

6-4. 10 Link Cataloging Program CHAIN Segments

Size and common allocation are the main considerations in Link Cataloging program
CHAIN segments. Since the primary method of argument passing between CHAIN segments is
through common, it is important that the first CHAIN segment specifies the common region as
being part of the program. (This occurs automatically unless otherwise specified. ) This is
necessary if the program is a foreground program, so that the proper memory requirements are
defined; or if the program contains BLOCK DATA, so that the common area is initialized
properly. It is equally important that all other CHAIN segments not include the common region
as part of the cataloged module since to do so would cause the common region to be destroyed
when the CHAIN segment is loaded for execution. To prevent the inclusion of common as part
of the CHAIN segment, a SEGMNT parameter would be specified on the TYPE control statements.
Because CHAIN segments are always loaded at the address of the first CHAIN segment, pro-
vision must be made to insure that the common region is at the same address relative to each
program CHAIN segment. This is done by issuing a CBASE control statement as each program
CHAIN segment is cataloged. The relative address specified on the control statement should
be identical for each CHAIN segment. If some or all program CHAIN segments do not use
common storage, then care must be taken to ensure that the first program CHAIN segment is
the largest one of the set.

NOTE

The function of program CHAIN segments to
provide program overlay capabilities is com-
pletely independent of the overlay type pro-
gram discussed in Paragraph 6-4. 1. Similarly,
the TYPE=SEGMNT control statement is un-
related to the SEGMENTcontrol statement. How-
ever, it should be noted, that a program CHAIN
segment may be an overlay type program.

6-40

Revision A
May, 1974

6-4. n Link Catalog Map

Upon successful compleHon of the linking process, a listing of the Link Cataloger
external table will be output to the List Output logical device (06) unless a NOMAP control
statement was previously issued. The map will consist of the program name (if any) followed
by two side-by-side columns of external, external equivalence, common, and system names
and values which will appear in alphabetic and numeric sequence, respectively.

The format of the Link Map is as follows.

P . NAME - LLLLLL

XXXXXX YYYYYY ZA XXXXXX YYYYYY ZA
XXXXXX YYYYYY ZA XXXXXX YYYYYY ZA

where: LLLLLL is the name of the program (as defined by the parameter on the
NAME control statement).

XXXXXX is the external, external equivalence, common block name,
or catalog parameter.

YYYYYY is the assigned octal memory location or value.

Z is a single character identifier which may be one of the following:

1) (blank) - indicates that the XXXXXX name is a Link Catalog
parameter.

2) C - indicates that the XXXXXX name is a common block.

3) S - indicates that the XXXXXX name is an external.

4) ^ - indicates that the XXXXXX name is an external equivalence
definition.

A is a single character identifier which may be one of the following:

1) (blank) - Indicates that the XXXXXX name was singly defined.

2) M - Indicates that the XXXXXX name was encountered more than
once. I.e., has a multiple definition.

3) U - indicates that the XXXXXX name was undefined. In the case of
external equivalences, the "U" indicates that at the time of the first
external equivalence request, the name XXXXXX was not defined. If
this occurs, the value of the external equivalence Is set to zero, and
subsequent definitions (if any) of XXXXXX are ignored.

The Link parameters that are passed back to the operating system also appear as an
XXXXXX name with a special format. The first character of the XXXXXX name of a link para-
meter is a special character ("*" or ". "). These names and their meanings are as follows:

*LOW The YYYYYY value associated with this name Is the relative low memory

address of the program.

*HIGH The YYYYYY value associated with this name Is the relative high memory
address of the program, If the program contains references to common,
then this address will be that of the highest element within the common
region. (This is not true when a SEGMNT parameter is given on a TYPE
control statement. )

*START The YYYYYY value associated with this name is the relative starting
address of the program.

6-41

Revision B
March, 1975

. BCOMM
.PASS

*P. END

*C. END

*STRT n

The YYYYYY value associated with this name is the lowest address of
blank common if defined in the program.

The YYYYYY value associated with this name is the number of passes
through the Library File necessary to satisfy external requests. If this
value is greater than one, then the modules on the library file are not
ordered or more than one library was processed.

The YYYYYY value associated with this name is the relative high
memory address of the program. This address does not include common
blocks, and is provided only when there are common blocks, and
TYPE SEGMNT is not used.

The YYYYYY value associated with this name is the relative high
memory address of the common area of a program. It is provided
only when there ore common blocks and TYPE^SEGMNT Is used.

The YYYYYY value associated with this name is the nth encountered
"starting address" after the first. The starting address actually used
is " * START " and is the first such address encountered. The
presence of these entries indicates additional "main" programs. If
this occurs, care should be taken to ensure proper functioning. More
than 9 additional "starting addresses" are ignored.

If the program being catalogued is an overlay type program, then the memory map
printed for the program is split into several parts. The first part corresponds to the main segment
(or root), and appears as a single program. However, only externals which are defined or
referenced in the main segment (or root) ore printed in the first part of the map. Each additional
part of the map corresponds to a particular segment. Each of these parts is headed by a line
with "SEGMENT" and the segment name on it. The map for each part lists only these externals
which are defined or referenced in the segment. Only two link parameters appear in these
sections. These are the high and low address In the segment, identified by *SG. HI and *SG. LO
respectively.

NOTE

Some of the externals defined in the segments
may appear with addresses that are not within
the segment. This is because the externals are
referenced outside of the segment and a refer-
ence to them may cause an overlay to take
place. Thus, the entry to these externals Is
made through the FLIPER table.

6-4. 12

Code Processing

The following paragraphs describe some of the more important codes that are processed
by the Link Cataloger. The processor(s) that produces the code is identified along with usage
consideration and the action taken by the Link Cataloger.

6-42

March, 1975

External DefiniHon

The Macro Assembler general-es an exfeMial definition for each XDEF pseudo -operation
encountered. The FORTRAN IV compiler generates external requests when the SUBROUTINE
or FUNCTION statements are processed. The code generated defines an address that is to be
associated with an external name. The name may be identical to an external equivalence or
Common Block name without conflict. If external definitions of the same name are encountered
in subsequent modules, then linkage will be made to the definition that was encountered first.
The module that contains the duplicate external definitions will not be loaded if it is encountered
on the Library File unless it also contains another definition that was previously requested but not
satisfied. If the module that contains the duplicate external definition resides on the Link Ready
file, then It will be unconditionally loaded. If the module is loaded, then any external names
that are defined more than once will be noted on the Link Map.

Externol Request

An external request Is generated by the Macro Assembler when an operand Is
encountered that is preceded by a dollar sign ($). External requests are also generated by the
FORTRAN IV Compiler any time subroutines or functions are determined to be external to the
program. External requests are also identified as to whether they are to be considered un-
conditional and conditional requests. Conditional external requests (denoted in assembly
language by preceding the operand by two consecutive dollar signs) are satisfied only if the
requested name was previously unconditionally requested. If the name was not unconditionally
requested prior to the conditional requests, then a BLU instruction to the system service routine
SABORT will be substituted for the requesting instruction.

System Service Request

A system service request is generated by the Macro Assembler when the instruction
BLU SXXX Is encountered.

If the requested external name Is found in the Link Cataloger's External Name table
(indicating that an external definition having that name has already been loaded), then a BLL
instruction Is inserted and the linkage is satisfied. If the requested external name is not found
In the Link Cataloger's Name table and Is in the DMS System Service table, a BLU Instruction
to the associated dedicated memory location is Inserted and the linkage is satisfied. If the
requested external name is not found In either table, a BLL Instruction Is loaded and the external
name is entered in the Link Cataloger's External Name table. For the linkage to be satisfied,
the requested external name must follow in a module residing on the Link Ready file or the
library file.

This function permits linkage to DMS System Services or user defined routines
irrespective of whether a particular service is resident within the operating system or on the
Library File. Services may also be added or deleted from the resident portion of the operating
system without re-assembling or compiling the requesting program.

External Equivalence Definition

External equivalence definitions are generated by the Macro Assembler when the
pseudo -operation "XEQV" is encountered. This definition defines a 24-bit constant which is
to be merged with the corresponding external equivalence request when encountered. This
function Is useful in externally defining data constants, channel/unit numbers or input/output
instructions, etc. The external equivalence name associated with the definition may be identical

6-43

Revision A
May, 1974

to an external or common block name without conflict. If multiple equivalence definitions of
the some name are encountered, the first one vyill be used as the definition and all subsequent
definitions of the same name are encountered, the first one will be used as the definition and all
subsequent definitions of the same name will be Ignored. However, the fact that the name was
defined more than once will be noted on the Link Map. External equivalence definitions are;
similar to Common definitions in that the external equivalence definition must precede any
external equivalence requests.

External Equivalence Request

External equivalence requests are generated by the Macro Assembler when an operand
is encountered that is preceded by a number sign {^). This request Indicates that the value
associated with the previously encountered external equivalence definition of the same name is
to merged (24-bit OR) with the requesting frame. If this is not done, the external equivalence
label will be flagged as undefined, whether or not a subsequent definition is encountered.

Common Definition

A common definition is generated by the Macro Assembler when the pseudo -operation
COMM is encountered, or the FORTRAN IV compiler when a COMMON statement is received.
The common definition specifies the size of the common area to the Link Cataloger so that
subsequent common requests may be assigned an address. The definition of the overall size of a
labeled common block must be identical In all programs and subprograms In which it is defined.
However, blank common areas defined in a set of programs and subprograms that are to be linked
do not have to correspond In size. The common block name associated with the common de- ;
finition may be identical to an external name or external equivalence name without conflict.^

Common Request

A common request is generated by the Macro Assembler or FORTRAN IV Compiler
whenever a reference Is made to a variable which has been declared to be in common. The
request carries the displacement from the common block name with which it is associated. For
example. If variables A, B, and C are declared to be In common (labeled or blank), then their
displacement from the block name is 0, 1, and 2 respectively. Common requests are distinguished
as to whether the address size Is 15 or 16 bits. Hence, 15-bIt common requests must reference
only those variables defined in the same memory bank as the request.

Name Definition

A name definition is generated by the Macro Assembler when the pseudo -operation
"NAME" is encountered, or by the FORTRAN IV Compiler when a "NAME" statement is received.

Source Program Error

A source program error code is generated by the Macro Assembler and the FORTRAN
IV Compiler when an irrecoverable error is detected. This code will immediately terminate
the link cataloging process and an error message will be output.

6-44

Commo n Origin

A common origin code is generated by the FORTRAN IV Compiler when a BLOCK
DATA subprogram is encountered. It defines a displacement from a common block name where
data is to be loaded.

END Code

An END Code is generated by the Macro Assembler and the FORTRAN IV Compiler
when an END statement is received. This code defines the end of the link module currently
being processed and causes the Link Cataloger to prepare to accept another module.

END-J ump Relative Code

An END-Jump relative code is generated by the Macro Assembler when an END
pseudo-operation is received which contains a relative operand expression. An address is
associated with this code which defines to the Link Cataloger the relative starting address of
the program being link catalogued. If more than one END-Jump relative code is received,
then the last one encountered will be used.

END-Jump Absolute Code

An END-Jump absolute code is generated by the Macro Assembler when an END
pseudo -operation is received which contains an absolute operand expression. This code must
not be presented to the Link Cataloger since only relocatable programs are processed.

Relative Origin

A relative origin code is generated by the Macro Assembler when the pseudo-operations
RORG and BLOK are encountered and by the FORTRAN IV Compiler when DIMENSION
statements are received. This code resets the relative location counter within the Link Cataloger.

Absolute Origin

An absolute origin code is generated by the Macro Assembler when the pseudo-
operation AORG or a BLOK pseudo -operation which was preceded by an AORG. This code
must never be presented to the Link Cataloger since only relocatable programs are processed.

ENDS Record

An ENDS record is generated by the Macro Assembler or the FORTRAN IV Compiler
when an END$ statement is received. This record is Ignored if option bit 6 Is not set.

6-45

Revision B
March, 1975

6-4. 13 Input and Code Placement

An input record to the Link Loader consists of 55 words: six 9-word subfields; and a
one-word, hash-total checksum. The first word of each 9-word subfield contains eight 3-bit
loader codes that determine the action to be taken for each of the following eight words In the
subfield (refer to Figure 6-1 1). Some codes require the use of multiple words to describe a
particular function in which case the codes corresponding to the extra words are set to zero.
If word 1 and word 55 of the input record are set to a -1 and all other words within the record
are set to zero, then the record is considered to be an END$ record.

Table 6-2 lists the various codes which are accepted by the Link Cataloger and
Table 6-3 lists the special action codes.

Table 6-2. Link Loader Input Codes

Code Bit
Configuration

Identification and Placement

000

Direct Load.

001

Memory Reference 15-bit.

010

External Definition - the first word contains the address to be
associated with the name which follows in the next two words.

External Request - the first word is the request frame with the
following bit settings:

BO = 0: 15-bit request.

BO = 1: 16 -bit request

Bl = 0: Unconditional request.

Bl = 1: Conditional request.

The request name follows within the next two words.

100

Memory Reference 16-bit.

101

Common Request 15-bit - the address filed in the first word contain^
the displacement from the block name specified in the next two words.

Special Action bits 16 through 20 determine the action to be taken
(Refer to Table 6-3).

111

Common Request 16-bit - the address field in the first word contains
the displacement from the block name specified in the next two words.

6-4<S

Table 6-3. Link Loader Special Action Codes

Special Action
Bit Configuration

Identification and Placement

00000

ORG Absolute - bits 0-15 of the word contains the absolute address.

00001

ORG Relative - bits 0-15 of the word contains the relative address.

00010

END

00011

END->Jump Absplute - bits 0-15 contains the absolute address to be
passed as the starting address.

00101

Internal String Back - bits 0-15 contain the address of the first link
in the chain to be strung.

oono

External String Back - bits 0-15 contain the address of the first link
in the chain; the next two words contain the external name.

00111

Name Definition - the next two words contain the name to he
associated with the program.

01000

Common Definition - bits 0-15 contain the size of the block; the
next two words contain the block name.

01001

Common Origin - bits 0-15 contain the displacement from the block
name contained in the next two words into which data is to be loaded.

01010

Source Program Error.

01011

System Service Request - the next two words contain the requested
external name.

01101

External Equivalence Definition - the next two words contain the
name and the following contains the equivalence value.

OHIO

External Equivalence Request - the next two words contain the name
and the following contains the instruction into which the request
value is "OR"ed.

6-47

24 Bits

Word 1

LU<

UL
CO

9
a.

U-
CQ

Z)
in

UJ<

u.
00

Code 1

Code 2

Code 3

Code 4

Codes

Code 6

Code 7

Code 8

Word 2

Load word 1

Word 3

Load word 2

Word 4

Load word 3

Word 5

Load word 4

Word 6

Load word 5

Word?

Load word 6

Words

Load word 7

Word 9

Load word 8

Word 10

Code 1

Code 2

Code 3

Code 4

Code 5

Code 6

Code 7

Code 8

Word 1 1

Load word 1

Word 12

Load word 2

Word 13

Load word 3

Word 14

Load word 4

Word 15

Load word 5 ^^ . -~-__^

■^' ■"^•n^

■

Word 50

Load word 4

-^ ^

Word 51

Load word 5

Word 52

Load word 6

Word 53

Load word 7

Word 54

^ Load word 8

Word 55

Checksum Word = Sum of words 1-54, Ignoring Overflow

Figure 6-11. Code Placement Format
6-48

6-4. 14 Link Cataloger Error Message Codes

During the linking process, extensive checking is performed to ensure ci proper program
load. If an error condition is detected, a message will be output to the list output logical
device (06). The format of the error message Is as follows.

LCT XX a'ABSOLUTE YYYYYY, RELATIVE ZZZZZZ IN MODULE AAAAAA**LINK ABORTED**

where: XX is a two-decimal digit error code. (The meanings of the error codes
are given in Table 6-4. )

YYYYYY is the memory address relative to the program (main plus sub-
routines) in which the error occurred.

ZZZZZZ is the qddress relative to the program module being linked in
which the error occurred.

AAAAAA is the last encountered external definition or name definition.
If no external or name definitions were encountered, "**MAIN" will
be output.

For some of the error messages listed in Table 6-4, the module name AAAAAA could
possibly be deceptive; hence, caution should be exercised.

Table 6-4, Error Messages

Number

Meaning

Invalid control statement.

A "TYPE" control statement was encountered after an ASSIGN control
statement.

An invalid parameter was encountered in the "TYPE" control statement.

Invalid delimiter following a parameter on a control statement.

An end -jump -relative code was encountered within an overlay segment.

File access specification on a "NAME" control statement is not "R",
"W", or "D".

The first character of the specified name on a "NAME" control statement
was not alphabetic.

An invalid common base specification was made on a "CBASE" control
statement.

An invalid pack number specification was made on a "NAME" control
statement.

An "ASSIGN" control statement was encountered with either an implied
or stated program type of background or re-entrant foreground.

An invalid logical device number was encountered on an "ASSIGN"
statement.

6-49

Revision A
May, 1974

Table 6-4. Error Messages (Cont'd. )

Numb
12

17
18
19
20
21

26
27
28

29
30
31

32
33
34

Meaning

A logical device number was assigned to more than one physical device
or file name.

A physical device number of file name was encountered on an "ASSIGN"
control statement that was un-recognizable.

A physical device number of zero or greater than '77 was encountered

on an "ASSIGN" control statement.

The number of assignments made has exc-eeded the available room in the

File/Device control block.

Character position 80 has been reached on a control statement without

having encountered a statement terminator.

Invalid link cataloger input code from the binary input stream.
An absolute origin code was encountered on the input stream.
An end -jump absolute code was encountered on the input stream,
A source program error code was encountered on the input stream.

Logical device '16 is assigned to a blocked disc file. The GO file must

be unblocked.

A labeled common block name was encountered that was not the same size

as previously encountered block of the same name.

Logical File 12 or 15 is not assigned to a disc file and overlay type program

specifications were entered.

The indicated segment has a zero length. None of the modules specified

for the indicated segment were found.

A common base was specified on a "CBASE" control statement such that

the program will overlap the common area.

String boundary violation.

Less than 336 locations are available in buffer area.

An external in the FLIPER table was referenced through an Instruction

which was not a BLL, BSL, BLI, BLJ, or BLK.

There is Insufficient background area to catalog the program.

The word count was not complete when a binary Input record was requested.

A checksum error was encountered on an input record which was requested

from the Link Ready File.

A checksum error was encountered on an input record which was requested

from the Library File.

A BLOCK DATA subprogram was encountered In a program which was

explicitly typed as being segmented (I.e., TYPE=SEGMNT).

A BLOCK DATA subprogram was encountered on the Library File.

6-50

Revision A
May, 1974

Table 6-4. Error Messages (Conrd. )

Number

Meaning

35
36
37

42
43

44
45

47
48
49

50
51
52
53

54
55

More than ten BLOCK DATA subprograms were encountered.

An attempt is being made to catalog a foreground program without a name.

An attempt |s being made to load data into the system common region via
a BLOCK DATA subprogram.

An end-of-file was encountered at an improper position on the Link Ready
file ('15).

An end-of-file was encountered at an improper position on the Library
file ('12).

An end-of-file is present on start of the Link Ready file. (i. e. , no
program is on the Link Ready file. )

Logical device '16 (the cataloged output of the Link Cataloger) is not
assigned to disc file.

A BLOCK DATA subprogram was encountered on nonndisc device.

Assignment statements were encountered when the program being
cataloged was specified as being a CHAIN segment.

Logical device '15 and '16 are assigned to the same disc file.

A 15 bit common request in a background program was encountered such
that an invalid reference across 32K memory partition would be made.

A 15 bit external request in a background program was encountered such
that an invalid reference across the 32K memory partition would be made.
(The external name is in one memory bank and the request is in the other
memory bank).

A foreground program exceeds 32K in size.

A resident foreground program was specified as being a CHAIN statement.

A "SYSCOM" definition was encountered that is greater in size than the
DMS System Common Area.

No modules are specified on a "MODULE" control statement.

"Read access" must b^ specified for Resident foreground programs.

Foreground programs cannot have a type "SYSGEN".

Overlay type is not "STNDRD", "NEW" or "UPDATE" on a "SEGMENT"
control statement.

Undefined parent segment specification on a "SEGMENT" control statement.

Segment name already specified on a previous "SEGMENT" control
statement.

Neither an "INCLUDE" or a "MODgLE" control statement has been
specified for an overlay segment.

Option specified is not one which may be cataloged with program.

6-51

vision C
avember 1975

Number

58
59

Table 6-4. Error Messages (Cont'd)

Meaning

Program exceeds 65 K.

Include or Library file does not exist. The missing file is identified
after "MODULE" in the error message.

6-52

SECTION VII
ACCOUNTING SUBSYSTEM

7-1 SCOPE

This section describes the accounting subsystem, an optional part of a_DMS
configuration. Included is a summary of the accounting considerations described m other parts
of this document along with a description of the use and operation of the DMS Accounting
Utility Program "ACCUP".

7-2 USER NUMBERS

User numbers are used to identify activities within a DMS system and to provide an
identifying number to which system usage can be allocated.

7-2. 1 Establishing User Numbers

User numbers can be added to a functional DMS system at ariy time and must be
entered through the operator communication device, via the "AU" (Add User) command. This
command provides for user number, account number and "^;;^^''^«"^'^':f '°\^^//^^J°J^"'^^^'^
for the command format). The u>er number must be a 1 -5 decimal digit number and ^f in °"
other occurrences, it must be preceded by the letter "U", i- e. , U 23. User number limits are
sePat system generation time for the individual installation. DMS provides for a maximum
range of 1 -65535.

Account numbers can be any integer valid on the Series 6000 computer and are used
by the Accounting Utility Program to provide another, larger grouping ^^V^,^"^^;^ P^'PJ'f '•
For instance, this might be a department number, which then allows the utility program to
summarize by department.

Name can be any 15 character string, the first of which, of course, is non-blank.
Individual DMS installations should establish a uniform naming convention. It is ^j;?'?;"^"'^^^^^^^
thalthe last name be entered first, since the alpha-sort feature of the Accounting Utility Program
assumes this format.

7-2. 2 Changing and Removing Users

User numbers can be removed and entries changed via other operator communication
entries. The "CU" (Change User) command provides the ability to specify a new account num-
ber' a new name, or both. The "RU" (Remove User) command removes a specified user from the
files. Refer to Table 9-1 for further information.

7-2. 3 Listing Users

The Accounting Utility Program provides the ability to list users either by number,
by account, or alphabetically by name, via use of the LIST command. See Paragraph 7^7 for
further information.

7-1

7-2. 4 Specifying User Numbers on Program Inil-iaHon

As stated earlier, a user number must be associated with the execution ot every
program in the accounting configuration of DMS. User numbers are associated with progroms
In a variety of ways as discussed in the following paragraphs.

7-2. 4. 1 Programs Initiated via Operator Communications

Any foreground program initiated via operator communications obtains its user
number from the user -number parameter that is required in accounting systems. The user number
must be the decimal number preceded by the letter "U". For example:

IP,XYZ,U 123,56

is used to initiate program XYZ with user number 123 at priority 56g,

Other commands which require a user-number are:

IP Initiate Program

SP Schedule Program for periodic execution

BP Begin Program at specific time

CP Connect Program to external interrupt

Additionally, the "SO" (Spool Output) operator communication command (refer to Table 9-1)
requires a user number for the execution of the Foreground -output-spooler program which this
command causes to be initiated. Its format is:

SO,FILENM,U123,terminal

7-2.4.2 Terminal Foreground Programs

Any foreground program initiated from a terminal under ACRONIM Is automatically
given the user number of the current terminal user. This was entered via the SON command
which is required to be the first command entered from a terminal in a DMS Accounting System.

7-2. 4. 3 Foreground Program? Initiated by other Pl-ograms

Any foreground program which is initiated via a System Service Call from another
foreground program is automatically given the user number of the program which requested the
initiation.

7-2. 4. 4 Background Batch Programs

Background batch programs are given the user number of the job In which they are
executing. AH Jobs in an accounting system must be preceded by a valid SJOB cqrd as discussed
in Section VI This SJOB card must contain a valid user number which is used for all program
executions for the duration of that job. The SJOB card must contain somewhere on it, in the
first 60 columns, a valid user number which is a decimal number preceded by the letter U .
For example:

SJOB CAT U123 D6

7-2

is used for a job named CAT run by user 123 wifh list output spooled to device 6,

7-3 TERMINAL OPERATION

Under an Accounting DMS System, a user number identifying the particular terminal
user is required at all times. ACRONIM executions are charged to this number and access is
allowed to the particular user's files via the user number.

The user number is initially established via a SON command whose format is:

SON Unnn

Where: Unnn is the decimal user number preceded by the letter "U". This user
number remains in effect until one of the following occurs:

a) A SOFF command is entered. This causes the terminal to be
turned off and a <ON is required to turn it back on.

b) A $JOB image is entered directly from the terminal with a
user number different from that of the current user. When
the '^EOJ (end-ot-job) image is received for the spooled
job, the terminal is turned off just as if a SOFF had been
entered. If the user number on the job card was the same as
the current one, the terminal retains its identity after the
$EOJ is encountered.

c) When another $ON command is entered. The first such
effectively becomes just a SOFF. Another SON is then
required to establish the identity of the user and turn on
the terminal.

It is important to nore that most accounting information for the terminal is not
written to disc until the terminal is terminated via the SOFF or similar commands as discussed^
above. Thus care should be taken that remote terminals are turned "off" before system operation
is terminated.

7-4 DISC FILES

The use of user numbers within the file security system of DMS has been discussed
in Section III. However, the important points are repeated below.

Each disc file created under the DMS Accounting System has associated with it a
user number. This is the user number of the creator of the file, i. e., the user number associated
with the program whose execution created the file. The user number is stored in the Master
Disc Directory entry in the 5th and 6th character positions of the password. (See Master Disc
Directory entry layout in Appendix A). Optionally, if the file was created without a user
number, such as if it were created under a non-accounting DMS system and then transferred to
an accounting version of DMS, then the first time a rename command is given for the particular
file, it will obtain the user number of the program doing the rename.

7-3

The user number provides access .o the file^ Ar,y prograrj, running -^J ♦^'= n'^^^'
user number is allowed to Reod, WrUe or Dele,e.nc^d,„g Re^^^^^

:Mhe^^s:^r::::ctd:rnrA^^^^^^^^
;tr^:^^r'^rar::=g!t,,fen-ir^^s

with user number 123 can write on or delete the file.

Thus it is important to supply the correct user number so that the correct files
can be accessed.

7-5 ACCOUNTING RECORDS

Accountina Records are 8-word blocks of information that summarize the usage of
o particular faciUty wTthirthe computer system. All accounting records have w.th.n them o
user number to which the usage is allocated.

Accounting records are collected in an in-core buffer and the buffer is written to

A variety of types of accounting records are generated. These are Hsted below.

1) CPU Record, containing CPU execution time in milliseconds and
core usage.

2) Disc Record, containing number of disc accesses and hundreds of words
transferred.

3) Console TTY Record, containing number of lines transferred from/
to operator communications device.

4) Individual I/O Device Records, one for each device used by a program,
containing length of time device was allocated, and number ot I/U
units transferred.

5) System Idle Time Records, containing the amount of CPU time that
the DMS system spent in the Executive Idle loop.

The exact layout and informational content of these records is given In Appendix B
of this document.

The in-core buffer Is cleared of all information when a "DA" (Dump Accounting)
command Is give: via operator communications. This should be done prior to closing down the
system to ensure that all information is stored on disc.

7-6 ACCOUNTING FILES

A number of special disc files are associated with the Accounting Subsystem These
ore a user number f,le, a u'ser name file, and Individual accounting record files to collect
accounting records.

7-4

7-6. 1

User Number File

The user number file, called "ACSUSR" with a password of "SYST" contains all
valid user numbers in a special format. The file has only public read access and only the system
can write to the file. The file contains one word per user number, sequentially from the lowest
user number in the system through the highest, packed 112 words per disc sector. See Figure 7-1.
A zero in the position for a user indicates an invalid number, while if the number itselt is stored
in the correct slot, then the user number is valid.

Sector

Sector 1

User Number A

User Number B

Zero's for

Unused

Positions

Sector N

Slot for lowest user
number in system as
determined at system
generation

Slot for highest user
number in system, as
determined at system
generation

Figure 7-1. User File Layout

7-6.2

User Name File

The user name file, called "ACSNAM" with a password of "SYST" contains the user
number, account number, and name of all users in the system. It is used for reports and summaries.
The file has public read access but can be written only by the system. This file is organized into
8-word segments, with one segment for each user. The file is not ordered and empty slots are
denoted by a 8-word block of zeros. The file is created by the system when first initialized
after a system generation if not already there, and made sufficiently large enough to hold all
of the users in the system.

7-5

Figure 7-2 shows an example of the two files, ACSSUR and ACSNAM when only
four users are in the system, as created by the following statements:

AU,U150,.3000,SMITH
AU,U400,. 3200, JONES
AU,U475,. 3200,THOMPSON
AU,U275,. 3200,HARRISON

Sector
Word 50

Sector 1
Word 63

Sector 2
Word 76

Sector 3
Word 39

ACSUSR

150

275

400

475

User limits set at system generation
are 100 and 500.

Sector

Sectors
1-28

A«NAM

150

3000

SMI

THK

p!pp

400
3200
JON
ESK

m
m
m
m

475

3200

THO

MPS

ONK

m
m

275

3200

HAt^

RIS

ONK

m
m
m

Zeros

Figure 7-2. Somple ACSNAM and ACSUSR Files

7-6

Word

Word 8

Word 16

Word 24

Words 32-111
(all zeros)

Revision A
May, 1974

7-b. 3 Accounfing Record Files

Accounting records are accumulated on disc In a series of disc files. These are name
"AC$nnn", where nnn is a decimal number from 001 through 999. The files are not necessarijy
in any order although the system does go sequentially when assigning numbers. The first Byword
block of all files is a date/time record whose layout is described In Appendix B, thus defining
the earliest record on the file. Thus all of the files can be ordered just by looking at the first
record. Files are either full (all sectors have information) or they are terminated with an end-
of-file mark. Eight-word records containing all zeros are fillers and should be bypassed when
processing the files.

An end-of-file record is always written following any accounting block. This is done
every time an in-core buffer is written to disc. The end-of-file mark allows the system to find
the end of the current file whenever the DMS system is loaded from disc. Thus in the event pf a
catastrophic system failure, only the information in core is lost, and all information written to
disc is preserved.

When DMS is loaded from disc, the system initialize program finds the latest disc file
by looking at the date/time record at the beginning of everv file and then scans to the EOF mark
in this file. This is where the first accounting records will oe written as computing operations
begin. The date/time entered by the Operator is compared with that on the disc file and if
found to be earlier than the disc file, a warning message is output.

If DMS cannot create an accounting file due to a lack of sufficient available space on
the accounting disc pack, it will output the message "ACCTG DISC FULL" to OPCOM. From
this point until room becomes available on disc, all accounting records will be lost. The first
accounting record generated after a 20 second interval will initiate another attempt to create
the file. These attempts and messages will continue until a file is successfully created.

7-7 ACCOUNTING UTILITY PROGRAM

The DMS Accounting Utility Program "ACCUP" provides a convenient means of preparing
simple summaries of accounting information and of maintaining the accounting record files. It is
a background batch utility program which can be run at any time as needed. ACCUP reods q
set of input parameter records from the job stream file, and then proceeds to execute based oh
this input. The control records are discussed In the following paragraphs. Thus a basic deck
structure for running ACCUP would be:

$JOB NAME Unnn etc
$ACCUP

control records
$EOJ

Of course, other job control records could be inserted in the job as required.

7-7. 1 RUN Command

The RUN command causes execution of the previous input to begin and signals the end
of the control statements. When processing has been completed, ACCUP will input more control
records from the job stream if any are present. And end-of-file on the input job stream file,
as caused by a $ control card, effectively generates a RUN command. However, ACCUP exits
when processing is complete.

7-7

1 -7 . 2 AccounHng Period D esignation Statements

The START and END statements provide information to define the extents of
accounting record processing, The basic format is:

END^ MM-DD-YY (HH:MM:SS)

where:

s the numeric month

s the numeric day

s the last two digits of the year

s the 24 -hour clock hours value

s the minutes value

s the seconds value

The time-of-day field is optional but if present, is input as a 24-hour clock value.

If no START command is given, then the earliest accounting information present v/ill
define the starting position. If a starting date is specified, but no time, then the earliest record
on or after the specified day will determine the start time.

If no END command is given then the accounting information to the end of the last
file will be processed. If an ending date is specified, but no time, then all records on the
specified ending date will be Included.

If neither the START nor the END parameters are input, then all available accounting
records will be Included.

Multiple START/END combinations may be entered to provide a summary containing
portions of a period of time. For instance, the following START/END pairs will summarize all
activity from Noon to 1 :00 p. m. for three consecutive days.

START

05-01-73