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IBM 7090/94 IBSYS Operating System

The IBSYS Operating System was supplied by IBM for the 7090/94 series. The system included a monitor program, the FAP assembler, FORTRAN II/IV, COBOL, and various utilities.

The FAP assembler was a modification of SAP (Symbolic Assembly Program) that was originally written by United Aircraft for the IBM 704 vacuum tube computer.

IBSYS Operating System Organization
Input/Output Executor (IOEX)Nucleus (IBNUC)Supervisor (IBSUP)Editor (IBEDT)System Core Dump (SYSDMP)
Utilities (DK90UT)9PAC Processor (9PAC)Commercial Translator Processor (CT)Input/Output Control System (IOCS)Generalized Sorting System (SORT)Restart Program (RESTART)IBJOB Processor (IBJOB)Symbolic Update Program (UPDATE)FORTRAN II Processor (FORTRAN)
Utility MonitorCommercial Translator MonitorIBJOB MonitorFORTRAN II Monitor
Disk/Drum Utilities & Tape DumpCompiler, Loader, Symbolic Maintenance (MAIN), & Subroutine Updater (SUBUP)COBOL Compiler (IBCBC)FORTRAN IV Compiler (IBFTC)Macro Assembler (IBMAP), Loader (IBLDR), Subroutine Library (IBLIB), & Debugging ProcessorFORTRAN II Compiler & FAP Assembler (including IBSFAP)

FAP and FORTRAN II could be used with either the IBM FORTRAN Monitor as an independent program or the same monitor as part of the 7090/94 IBSYS Operating System.

The Monitor was controlled with Control Cards that were identified with an asteric in column one.

An example Job Deck is:

*ID JOB NO. 3794 COZMIC                                 (First Card in Job Deck -- Identified Beginning of Job)
* XEQ (...This Job is to be Executed...)
* FAP (Tells Monitor that Following Program is in FAP)
(FAP Source Deck -- Last Card is END)
FORTRAN (Tells Monitor that Following Program is in FORTRAN)
(FORTRAN Subroutine Source Deck -- Last Card is END)
(FORTRAN Subroutine Source Deck -- Last Card is END)
DATA (Tells Monitor No More Source -- Data Follows...)
(Data Cards if Any)

The IBSYS operating system was a more comprehensive monitor that could run many different software packages depending on the needs of the current job. Control cards for IBSYS were identified by having a '$' in column one with a Control Name following immediately after the '$'. An example Job Deck to run a FORTRAN program under IBSYS is:

$JOB                  (First Card of a job)
$EXECUTE IBJOB (Calls IBJOB Monitor that Contains the FORTRAN IV Compiler)
$IBJOB GO, (options) (Specified GO Execution Option in IBJOB)
$IBFTC DECK1 Options (Specified FORTRAM IV, Deck Name, and Compiler Options)
(Program Source)
$DATA (Data Follows)
7/8EOF (Last Card of a Job -- First Card Column has 7 and 8 punches :)

The IBSYS Operating System required eight tape drives with two channels in order to run.

If an IBM 1301 disc drive or a 7320 drum storage unit was available, then IBSYS could operate with only four drives. The FORTRAN Monitor alone (not part of IBSYS) required seven tape drives -- or six tape drives and a disc drive. -- Last Revision: 23 August 2001
Copyright © 1996 - 2015 Jack Harper (unless otherwise noted)
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