IBM System/360 Model 50: Difference between revisions

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

{{Infobox information appliance

| name = IBM System/360 ModeModel 50

| title =
| aka =

| aka logo_size = 120px

| image_size = 270px

| logo = File:IBM logo.svg

| image = File:IBM system 360-50 console - MfK Bern.jpg

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| developer =

| manufacturer = International Business Machines Corporation ([[IBM]])

| family = [[System/360]]

| type =

| generation =

| releasedate = {{Start date|1964|04|07}}

| lifespan =

| price =

| discontinued = {{End date|1977|03|15}}<ref>{{cite web|last1=IBM Corporation|title=IBM Archives: System/360 Model 50|url=https://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2050.html|website=IBM Archives|accessdatedate=June23 29,January 20172003|archive-url=https://web.archive.org/web/20230928074645/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2050.html|archive-date=2023-09-28|url-status=dead}}</ref>

| unitssold =

| unitsshipped =

| media =
| os =

| os power =

| power soc =

| soc cpu =

| memory = 64–512 KB Core

| cpu =

| storage =

| memory = 64–512 KB Core

| storage memory card =

| memory card display =

| display graphics =

| graphics sound =

| sound input =

| input controllers =

| controllers camera =

| camera touchpad =

| touchpad =

| connectivity =

| platform =

| service =

| dimensions =

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| predecessor =

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The '''IBM System/360 Model 50''' is a member of the [[IBM System/360]] family of computers. The Model 50 was announced in April 1964 with the other initial models of the family, and first shipped in August 1965 to the [[Bank of America]].<ref name=Pugh>{{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|year=1991|publisher=MIT Press|isbn=978-0-262-16123-7}}</ref>

==Models==

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===Relative performance===

The system has a CPU cycle time of 500 nanoseconds, 25% faster than the [[IBM System/360 Model 40|Model 40]] and 40% slowerof thanthe speed of the [[IBM System/360 Model 65|Model 65]] which has a 200 nanosecond cycle time. Processor storage is [[magnetic core memory]] that transfers four bytes per 2 microsecond cycle. It has "protected" and "local" core storage for registers and internal buffers with cycle times of 200 and 500 nanoseconds respectively.

==Features==

The Model 50 implements the complete [[IBM System/360 architecture|System/360 "universal instruction set" architecture]], including floating-point, decimal, and character operations as standard features. The "direct control" instructions are an optional feature. Optional logic, microcode and software providing compatibility with either the [[IBM 1410|IBM 1410/7010]] or [[IBM 7070|7070/7074]] systems is available.

An [[IBM 1050|IBM 1052]] printer/keyboard for use as an operator's console is optional. The I/O options include one [[channel-to-channel adapter]] (CTCA) and up to three [[Channel I/O|selector channel]]s. A [[Channel I/O|multiplexer channel]] for attachment of slow-speed devices is standard on all models. The F50 has 64 subchannels, so it can attach up to 64 slow-speed devices on its multiplexer channel. The other models have 128 subchannels. This can optionally increase to 256 subchannels on the H50 and I50.<ref name="FuncChar">{{cite book|publisher=IBM|title=IBM System 360 Model 50 Functional Characteristics|id=A22-6898-1|date=1967|url=http://www.bitsavers.org/pdf/ibm/360/funcCharfunctional_characteristics/A22-6898-1_360-50_funcChar_1967.pdf|accessdate=Sep 20, 2016}}</ref>

==Microcode==

The Model 50 uses a 90&nbsp;bit (or 85&nbsp;bit, depending on definition) "horizontal microcode" instruction format, with each word containing 15 (or 25) separate fields.<ref>{{cite web|last1=Smotherman|first1=Mark|title=A Brief History of Microprogramming|url=http://ed-thelen.org/comp-hist/MicroprogrammingABriefHistoryOf.pdf|accessdate=Sep 26, 2015}}</ref> There are 2816 words of microcode storage.<ref>{{cite book|editor-last1=Kent|editor-first1=Allen (ed)|editor-last2=Williams|editor-first2=James G. (ed)|title=Encyclopedia of Computer Science and Technology volume 28|date=1993|publisher=CRC Press|isbn=978-0-8247-2281-4|page=39|url=https://books.google.com/books?id=EjWV8J8CQEYC&printsec=frontcover#v=onepage&q&f=false|accessdate=Sep 26, 2015}}</ref>

Read-only control storage for microcode employs "balanced capacitor technology" (BCROS) with a cycle time of 500 nanoseconds, designed by Anthony Proudman in [[IBM Hursley|IBM's Hursley laboratory]] and implemented by Fernando "Fred" Neves. This technology uses two [[capacitor]]s to represent each bit.

[[File:IBM1970 360-50,CNRZ ZETOMécanographie-8-cliche ZOWARJean (I197703)Weber.jpg|thumb|right|B&W closeup of 360/50 console]]

[[File:IBM 360-50, ZETO ZOWAR (I197703).jpg|thumb|right|B&W closeup of 360/50 console]]

==System software==

It was possible to choose [[DOS/360]], [[OS/360 and successors#MFT|OS/360 MFT]] (Multi-programming with a Fixed number of Tasks), or [[OS/360 and successors#MVT|OS/360 MVT]] (Multi-programming with a Variable number of Tasks) as the [[Operatingoperating Systemsystem]] of an IBM System/360 Model 50. Few chose MVT.<ref name="most-didnt-run-mvt">{{cite mailing list|url=https://groups.google.com/forum/#!original/bit.listserv.ibm-main/zqAApnIeXec/qZ-fhTcVKz0J|title=Re:the 40thconsole anniversarysubsystem ofpriority IBM|via=Google System/360Groups on 7 Apr 2004|date=January 18, 2004|author=William H. Blair|mailing-list=ibm-main|quote=Your point is well taken. But most didn't run MVT, and many that did had LCS (Large Capacity Storage). MVT was not very popular. Nonetheless, I ran a system that ran MVT just fine with only 256MB; maximum REGION size was 114MB, which was perfectly fine for the workload. I suspect that if MVT was being used on a /65 or /75, then 512KB was installed. But, there were a lot of folks that ran MVT on a /50 with 384KB. We got blood out of the turnip back in those days. |url-status=live |archive-url=https://archive.today/20240410212204/https://groups.google.com/g/bit.listserv.ibm-main/c/zqAApnIeXec/m/qZ-fhTcVKz0J |archive-date= 10 April 2024 }}</ref>

The choice of operating system for the System/360 Model 50 was based primarily on the amount of main storage. The F50, with 65,536 bytes of main storage, can not run OS/MFT, which requires a minimum of 131,072 bytes of main storage.<ref>{{cite book|url=http://bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC27-6939-10_MFT_Guide_R21.7_Mar72.pdf|title=IBM System/360 Operating System: MFT Guide OS Release 21.7|id=GC27-6939-10|publisher=IBM|date=March 1972|page=69 |via=bitsavers |url-status=live |archive-url= https://web.archive.org/web/20231224064716/http://bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC27-6939-10_MFT_Guide_R21.7_Mar72.pdf |archive-date= Dec 24, 2023 }}</ref>

DOS/360 has a minimum of 16,384 bytes of main storage.<ref>{{cite book|url=http://bitsavers.org/pdf/ibm/360/dos/GC24-5030-8_Disk_and_Tape_Operating_Systems_Concepts_and_Facilities_Oct70.pdf|title=IBM System/360 Disk and Tape Operating Systems Concepts and Facilities|id=GC24-5030-8|publisher=IBM|date=October 1970|page=5}} &ldquo;|via=bitsavers |quote=Disk and Tape Operating Systems are comprehensive sets of language translators and service programs operating under the supervisory coordination of an integrated control program. They require an IBM System/360 with at least 16K bytes of main storage.&rdquo; |url-status=live |archive-url=https://web.archive.org/web/20231224064716/http://bitsavers.org/pdf/ibm/360/dos/GC24-5030-8_Disk_and_Tape_Operating_Systems_Concepts_and_Facilities_Oct70.pdf |archive-date= Dec 24, 2023 }}</ref>

Systems with 131,072 or more bytes of main storage could run OS/360. Although 360/50 systems equipped with 1 MB or more<ref>{{cite conference|url=https://books.google.com/books?id=_BGDRGWzVw4C&pg=PA33&lpg=PA33|title=Using SMF and TFLOW for Performance Enhancement|conference=Eighth Meeting of Computer Performance Evaluation Users Group (CPEUG)|author=J. M. Graves|year=1974}}</ref> could and did run MVT<ref>{{cite mailing list|url=http://www.classiccmp.org/pipermail/cctalk/2015-May/006672.html|title=Re: 360/50 microcode listing|mailing-list=[e-mail]|date=May 7, 2015}}</ref><ref>{{cite web|url=https://www3.epa.gov/storet/pptfiles/manning.ppt|archive-url=https://web.archive.org/web/20040711025501/http://www.epa.gov/storet/pptfiles/manning.ppt|url-status=dead|archive-date=July 11, 2004|title=An overview of the history of development of the EPA STORET System, with some comments on future timelines and plans.|date=November 7, 2001|page=3|format=PPT}}</ref> one IBMer described this as "[getting] blood out of the turnip", and noted that "most didn't run MVT".<ref name="most-didnt-run-mvt"/>

Reasons for a 360/50 site to run MFT<ref>{{cite newsgroup|url=https://groups.google.com/forum/#!original/alt.folklore.computers/3H0Iz7lGHYE/_Gk2OHyKshoJ|title=Re: Price of core memory|author=Gerard S.|date=June 1, 2001|newsgroup=alt.folklore.computers|quote=We had to revert to MFT to get a 98K partition, plus a reader and writer.}}</ref> rather than MVT were:

* MVT's minimum memory requirements of 256KB<ref>{{cite book|quote=The minimum main storage is 262,144 (256K) bytes|url=http://www.bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC28-6720-5_MVT_Guide_Rel_21.7_Aug74.pdf|title=IBM System/360 Operating System: MVT Guide|date=August 1974|publisher=IBM|id=GC28-6720-5}}</ref><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|id=GC28-6551-16|publisher=IBM|date=April 1973}}</ref> - the F50 and G50 models hadhave less;

* CPU power: the next larger System/360, the [[IBM System/360 Model 65|Model 65]], hadhas triple the power.<ref name="Padegs">{{cite journal|last = Padegs |first = A.|date = September 1981|title = System/360 and Beyond|journal = [[IBM Journal of Research and Development]]|doi = 10.1147/rd.255.0377|volume=25 |issue=5 |pages=377–390}}</ref><ref>A convenience sample of ads for used 360/50 and 360/65 configurations in the back of Computerworld for the 1971 - 1973 period show mostly MVT installed on 360/65 OS and NOT EVEN ONE 360/50 with MVT</ref>

==={{Anchor|CALL/OS}}Time-sharing (CALL/OS)===

IBM advertised [[time-sharing]] capability<ref>{{cite book

IBM advertised [[time-sharing]] capability by featuring what originally was known as CALL/360<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/CALL_360_Terminal_Reference_Manual_Sep69.pdf|title=CALL/360: Terminal Reference Manual|publisher=IBM|year=1969}}</ref> (note the 'SLASH' - which was retained in the name of its successor) and later<ref>{{cite web|url=http://ed-thelen.org/2005MiniGE-Reunion.html|title=2005 Mini GE-Reunion|author=Ed Thelen}}</ref> was named '''CALL/OS'''. CALL/OS featured its own versions of [[BASIC]] <ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/CALL_360_BASIC_Reference_Handbook_1970.pdf|title=CALL/360: BASIC Reference Handbook|publisher=[[Service Bureau Corporation]]|year=1970}}</ref> as well as [[Fortran|FORTRAN IV]]<ref name="dissim">{{cite journal|url=https://link.springer.com/content/pdf/10.3758%252FBF03201546|title=The calculation of the index of dissimilarity on a computer terminal|author=Jerry W. Wicks|journal=Behavior Research Methods & Instrumentation|volume=7|issue=4|page=380|year=1975|quote=The program (Dissim) is written in Call-os Fortran IV and is now in use on an IBM 360/75 with teletypewriter remote facilities.}}</ref> and [[PL/I]],<ref>{{cite journal|url=https://archive.org/details/creativecomputing-1980-11|title=Adventure (letter to the editor)|author=Timothy Marino|journal=[[Creative Computing]]|volume=6|issue=11|date=November 1980|page=12|quote=Can you or any of your readers direct me to a version of Adventure written in standard Basic, Fortran, or IBM Call-OS PL/I?}}</ref><ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/GY20-0567-1_CALL_360_PL1_System_Manual_Vol_1_Jan71.pdf|title=CALL/360 - OS PL/I System Manual - Volume I|id=GY20-0561-1|date=January 1971|publisher=IBM}}</ref> rather than the versions implemented by the MFT/MVT compilers known as FORTRAN G, FORTRAN H and PL/I F. CALL/OS is sometimes referred to as "CALL-OS".<ref>{{cite book|title=CALL-OS: learning FORTRAN; terminal-oriented self-study text|publisher=IBM|year=1972}}</ref>

|title=100 Days: How Four Events in 1969 Shaped America

|quote=... a happy timeshare user .. 'This man is sharing a $2 million computer.'

|isbn=978-1538125915 |publisher=Rowman & Littlefield Publishers

IBM advertised [[time-sharing]] capability|author=Harlon Lebo |year=2019}}</ref> by featuring what originally was known as CALL/360<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/CALL_360_Terminal_Reference_Manual_Sep69.pdf|title=CALL/360: Terminal Reference Manual|publisher=IBM|year=1969}}</ref> (note the 'SLASH' - which was retained in the name of its successor) and later<ref>{{cite web|url=http://ed-thelen.org/2005MiniGE-Reunion.html|title=2005 Mini GE-Reunion|author=Ed Thelen}}</ref> was named '''CALL/OS'''. CALL/OS featured its own versions of [[BASIC]] <ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/CALL_360_BASIC_Reference_Handbook_1970.pdf|title=CALL/360: BASIC Reference Handbook|publisher=[[Service Bureau Corporation]]|year=1970}}</ref> as well as [[Fortran|FORTRAN IV]]<ref name="dissim">{{cite journal|url=https://link.springer.com/content/pdf/10.3758%252FBF03201546|title=The calculation of the index of dissimilarity on a computer terminal|author=Jerry W. Wicks|journal=Behavior Research Methods & Instrumentation|volume=7|issue=4|page=380|year=1975|quote=The program (Dissim) is written in Call-os Fortran IV and is now in use on an IBM 360/75 with teletypewriter remote facilities.|doi=10.3758/BF03201545|doi-access=free}}</ref> and [[PL/I]],<ref>{{cite journal|url=https://archive.org/details/creativecomputing-1980-11|title=Adventure (letter to the editor)|author=Timothy Marino|journal=[[Creative Computing]]|volume=6|issue=11|date=November 1980|page=12|quote=Can you or any of your readers direct me to a version of Adventure written in standard Basic, Fortran, or IBM Call-OS PL/I?}}</ref><ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/call_360/GY20-0567-1_CALL_360_PL1_System_Manual_Vol_1_Jan71.pdf|title=CALL/360 - OS PL/I System Manual - Volume I|id=GY20-0561-1|date=January 1971|publisher=IBM}}</ref> rather than the versions implemented by the MFT/MVT compilers known as FORTRAN G, FORTRAN H and PL/I F. CALL/OS is sometimes referred to as "CALL-OS".<ref>{{cite book|title=CALL-OS: learning FORTRAN; terminal-oriented self-study text|publisher=IBM|year=1972}}</ref>

Installations with a larger model of the System/360 family sometimes ran/retained the combination of MFT and CALL/OS,<ref name="dissim"/> rather than switch to MVT, a pre-requisite for [[Time Sharing Option|TSO]],<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/os/tso/GC28-6698-5_Time_Sharing_Option_Guide_Jul72.pdf|title= IBM System/360 Operating System: Time Sharing Option Guide|id=GC28-6698-5|publisher=IBM|date=July 1972}}</ref> after an upgrade.

IBM System/360 Operating System: Time Sharing Option Guide|id=GC28-6698-5|publisher=IBM|date=July 1972}}</ref> after an upgrade.

==References==

{{Reflist}}

==External links==

*{{cite web |first=Ken |last=Shirriff |title=Simulating the IBM 360/50 mainframe from its microcode |date=January 2022 |url=http://www.righto.com/2022/01/ibm360model50.html}}

{{IBM System/360 line}}

{{DEFAULTSORT:IBM System 360 Model 50}}

[[Category:IBM System/360 mainframe line|System/ 360 Model 50]]