IBM System/360 Model 40: Difference between revisions

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{{Short description|IBM computer model from 1960s}}

{{Infobox information appliance

{{Infobox computing device

| name = IBM System/360 Model 40

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| aka =

| logo logo_size = File:IBM logo.svg120px

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| logo = File:IBM Logo 1956 1972.svg

| image = File:IBM System 360 at USDA.jpg

| caption = IBM System/360 Model 40 at the USDA

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The '''IBM System/360 Model 40''' was a mid-range member of the [[IBM System/360]] family. It was announced on April 7, 1964, shipped in 1965, and withdrawn on October 7, 1977.<ref>[http{{cite web|url=https://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2040.html |title=IBM Archives: System/360 Model 40] (|website=IBM|date=23 Archives)January 2003|archive-url=https://web.archive.org/web/20231209150627/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2040.html|archive-date=2023-12-09|url-status=dead}}</ref><ref>[https://www.flickr.com/photos/dabcanboulet/131523955/ IBM System/360 model 40] (Flickr from Yahoo!)</ref>

[[File:IBM System 360 Model 40 with open gates.jpg|thumb|360/40 with circuit gates open]]

[[File:IBM-360-40 w Starachowicach_FSC, pami%C4%99%C4%87 zewn%C4%99trzna (I197412).jpg|thumb|360/40 configuration]]

==History==

On April 7, 1964, IBM announced the [[IBM System/360]], to be available in six models.<ref>{{cite book|url=https://books.google.com/books?id=Bc8BGhSOawgC&pg=PA275&lpg=PA275|title=Building IBM: Shaping an Industry and Its Technology|author=Emerson W. Pugh|year=1995|publisher=MIT Press|page=275|___location=Cambridge, Massachusetts|isbn=0-262-16147-8}}</ref><ref>{{cite book|title=From Mainframes to Smartphones|author1=Martin Campbell-Kelly|author2=Daniel D. Garcia-Swartz|year=2015|publisher=[[Harvard University Press]]|isbn=9780674729063}}</ref><ref>Fortune magazine, Sept. 1966, p.118</ref> The 360/40 was first delivered in April 1965.<ref>{{cite web|url=https://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS360.html|title=IBM Archives: System/360 Dates and characteristics|publisherdate=IBM23 January 2003|archive-url=https://web.archive.org/web/20230422131739/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS360.html|archive-date=2023-04-22|url-status=dead}}</ref>

The [[IBM System/360 Model 30|360/30]] and the 360/40 were the two largest revenue producing [[IBM System/360#SummaryTable of modelsSystem/360 shippedmodels|System/360 models]],<ref name=IBMbook>{{cite book|last1=Pugh|first1=Emerson W.|last2=Johnson|first2=Lyle R.|last3=Palmer|first3=John H.|title=IBM's 360 and early 370 systems|url=https://archive.org/details/ibms360early370s0000pugh|url-access=registration|date=1991|publisher=MIT Press|___location=Cambridge, Massachusetts|isbn=9780262161237}}</ref> accounting for over half of the units sold.<ref>An [[Automatic Data Processing|ADP]] Newsletter cited on page 56 in {{cite book|editor-last=Weiss|editor-first=Eric A.|title=Computer Usage Essentials|date=1969|publisher=McGraw-Hill|lccn=71-76142}} shows sales of the 360 Model 30 (36%) and the Model 40 (22.6%), for a total of 58.6%</ref>

==Models==

Five models of the 360/40 were offered.<ref name="mod40-func-char">{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/funcCharfunctional_characteristics/A22-6881-2_360-40_funcChar.pdf|title=IBM System/360 Model 40 Functional Characteristics|id=A22-6881-2|date=August 1971}}</ref> The D40, E40, F40, G40 and H40 were configured with 16K, 32K, 64K, 128K and 256K of [[Magnetic-core memory|core memory]] and correspondingly 16, 32, 64, 128 and 128 <ref group='NB'>not a typo: the physical limit seemed to be 224; see p. 17 of the Model 30 Functional Characteristics</ref> multiplexer subchannels.<ref name="mod40-func-char"/>

The H40 occupied "more floor space than the other models."<ref name="mod40-func-char"/>{{rp|p.5}}

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==Microprogramming==

[[Image:IBM 360 20 TROS.jpg|thumb|300px|[[Transformer matrixread-only ROMstorage]] (TROS), from the IBM System 360/40]]

Like most System/360 models the Model 40 wasis [[microcode|microprogrammed]]. The microcode wasis stored in [[Transformertransformer Readread-only Only Storagestorage]] (TROS), organized as up to 8192 words of 56 bits each. Standard microcode consistedconsists of up to 4096 words. The additional 4096 words wereare used for the 1401 or 1410 compatibility feature.<ref name="FE">{{cite book |last1=IBM Corporation |title=IBM Field Engineering Manual of Instruction: System/360 model 40 Functional Units |date=1970 |pages=52–73 |url=http://bitsavers.org/pdf/ibm/360/fe/2040/SY22-2843-1_Model_40_Functional_Units_Mar70.pdf}}</ref>

==IBM 1400 series emulation==

With the additional Compatibility Feature hardware and Compatibility Support software under DOS/360, the [[IBM 1401]]/[[IBM 1440|1440]]/1460 object programs couldcan be run in the emulation mode, with little or no reprogramming.<ref>{{cite book|url=http://bitsavers.org/pdf/ibm/360/dos/C27-6940-2_14xx_Emulator_Feb69.pdf|title=IBM System/360 Disk Operating System 1401/1440/1460 Emulator Programs: Compatibility Support/30 & /40|id=C27-6940-2|edition=Third|date=February 1969|publisher=IBM}}</ref>

==Other==

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the IBM [[operating system]] used was usually the realistically sized [[DOS/360]],{{Citation needed|date=September 2017}} because all but one model of the 360/40 had less than MVT's minimum memory requirements of 256KB.<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC28-6551-16_Storage_Estimates_R21.7_Apr73.pdf|title=IBM System/360 Operating System: Storage Estimates OS Release 21.7|date=April 1973|publisher=IBM|id=GC28-6551-16}}</ref><ref>{{cite web|author=Ray Saunders |url=http://www.os390-mvs.freesurf.fr/mvs360.htm |title=MVS... And Before OS/360 ? |archive-url=https://web.archive.org/web/20071220191855/http://www.os390-mvs.freesurf.fr/mvs360.htm |archive-date=2007-12-20}}</ref>

The IBM System/360 Model 40 was developed at [[IBM Hursley]]<ref>{{cite journal|url=http://www.cs.man.ac.uk/CCS/res/res23.htm|title=Editorial|author=Nicholas Enticknap|journal=Resurrection: The Bulletin of the Computer Conservation Society|issue=23|quote=Mike Flinders, who also worked at Hursley where the 360/40 was designed}}</ref> and manufactured at IBM's facilities in: Poughkeepsie, U.S.New York, [[Mainz]], Germany; and [[Fujisawa, Kanagawa|Fujisawa]], Japan.<ref>{{cite web|url=https://www-03.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV8001.html|title=IBM Archives: Fujisawa plant|website=IBM|date=23 ArchivesJanuary 2003|archive-url=https://web.archive.org/web/20230924020615/https://www.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV8001.html|archive-date=2023-09-24|url-status=dead}}</ref>

A modified Model 40 ran [[CP-40]], the ancestor of [[CP/CMS]], which in turn was the progenitor of the [[z/VM|VM]] line.