IBM System/360 Model 20: Difference between revisions

Revision as of 20:44, 17 February 2023

Revision as of 21:04, 17 February 2023

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===2311 Disk Storage===

Model 20 disk storage uses [[History of IBM magnetic disk drives#IBM 2311|IBM 2311 disk drives]], model 11 or 12, attached to an integrated "storage control feature" on the CPU.<ref name=FuncChar />{{rp|pp.58–76}} If multiple drives are attached they have to be the same model. Both models use the 1316 [[disk pack]] which provides a maximum of 203 [[Cylinder (disk drive)|cylinders]] with 10 [[Track (disk drive)|tracks]] per cylinder. The model 11 uses all cylinders, the model 12 uses only the outermost 103. Each track is divided into ten [[Disk sector|sector]]s of 270 bytes each. The model 11 has a formatted capacity of 5.4&nbsp;million bytes, and the model 12 of 2.5&nbsp;million.<ref>[{{cite book |url=http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/ibm/dasd/2311/Y26-5897-4_2311_FE_Theory_Of_Operation_Oct674_2311_Models_1_11_12_FETOM_196710.pdf "|title=IBM Field Engineering Theory of Operation 2311 Disk Storage Drive Models 1, 11 and 12 Field|id=Y26-5897-4 Engineering Theory of Operation"|publisher=[[IBM]]}} describes the IBM 2311, including models 11 and 12, used on System/360 model 20</ref>

===IBM 2560 Multi-Function Card Machine===

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===Disk Programming System===

The '''Disk Programming System (DPS)''' is a control program for a Model 20 with at least 12&nbsp;KiB of memory and one disk drive. The components of DPS are:<ref>{{cite book|last=IBM Corporation|title=IBM System/360 Model 20 Disk Programming System Control and Service Programs|yearedition=Fifth|date=March 1969|url=http://bitsavers.trailing-edge.com/pdf/ibm/360/model20/C24-9006-4_260-20_CtlPgm_Mar69.pdf|id=C24-9006-4|publisher=[[IBM]]}}</ref>

* The ''[[Initial Program Load#IBM Initial Program Load|Initial Program Loader]]'' (IPL).

* A small ''resident monitor'' which handles disk input/output, error recovery, and job-to-job transition, and loads programs to be executed from the ''core-image library'' on disk.

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On such systems TPS provides an assembler and tape manipulation utility programs.

Additional capabilities are provided on systems with 8192 bytes of main storage,

and still more with four or more magnetic tape drives.<ref>[{{cite book |url=http://bitsavers.trailing-edge.comorg/pdf/ibm/360/model20/C24-9009-3_TPS_OperProcedures_Mar69.pdf |title=IBM System/360 Model 20 Tape Programming System Operating Procedures |edition=Fourth |date=March 1969 |id=C24-9009-3 |publisher=[[IBM]] "|quote=This publication provides Model 20 operators with the information required to operate their systems using the Model 20 Tape Programming System (TPS)"}}</ref>{{rp|pp.pages=42-43}}

===Card Programming Support===

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===Languages===

* [[IBM RPG|Report Program Generator (RPG)]].

* [[PL/I]] subset, DPS only.<ref>{{cite book|last=IBM Corporation|title=IBM System/360 Model 20 Disk Programming System PL/I|yearedition=First|date=December 1968|url=http://bitsavers.trailing-edge.com/pdf/ibm/360/model20/C33-6007-1_360-20_PLI_Dec68.pdf|id=C33-6007-1|publisher=[[IBM]]}}</ref>

* [[IBM Basic assembly language|Basic Assembler]] versions were available for CPS, TPS, and DPS including [[Input/Output Control System]] (IOCS) macros and processing routines.