IBM System/360 Model 30: Difference between revisions

Revision as of 04:25, 14 September 2020

Revision as of 15:45, 3 January 2021

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==History==

The Model 30 was a popular [[IBM mainframe]] which was announced in 1964 as the least powerful of the [[IBM System/360|System/360]]s. The System/360 series was the first line of computers in the world to allow machine language programs to be written that could be used across a broad range of compatible machines of different sizes. It was the smallest model that had the full [[System/360]] instruction set (unlike the [[IBM System/360 Model 20|Model 20]]) and served as a stand-alone system, communications system or as a satellite processor of a larger system.<ref name="ibm-archives">{{cite web|title=IBM Archives: System/360 Model 30|url=https://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2030.html|website=IBM|accessdateaccess-date=16 August 2016}}</ref>

The first delivery of the 360/30 was in June 1965 to [[McDonnell Aircraft]].<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, Mass.|isbn=9780262161237}}</ref>

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[[Emulator|emulated]] by the [[microprogram]].<ref name="30theory">{{cite book|url=http://bitsavers.org/pdf/ibm/360/fe/2030/Y24-3360-1_2030_FE_Theory_Opns_Jun67.pdf|title=Field Engineering Theory of Operation, 2030 Processing Unit, System/360 Model 30|id=Y24-3360-1|edition=Fifth|date=June 1967|publisher=IBM}}</ref><ref>{{cite book|url=http://bitsavers.org/pdf/ibm/360/fe/2030/Model_30_Microprogramming_Lang.pdf|title=Model 30 Microprogramming Language|publisher=IBM}}</ref> Handling a 4-byte word took (at least) 6 microseconds, based on a 1.5 microsecond storage access cycle time.<ref name="30theory"/>{{rp|pg.1–4}}

The microcode was stored in [[CCROS]] (Card Capacitor Read-Only Storage) developed in Endicott. The Model 30 and Model 40 were originally supposed to share the [[transformer read-only storage]] (TROS) being developed at [[IBM Hursley]], but CCROS was cheaper to manufacture.<ref name= ibmbook/> This system used [[Mylar]] cards the size and shape of a standard IBM [[punched-card]], so the microcode could be changed using a [[keypunch]]. Each card held 720 bits, and the total microcode consisted of 4032 60-bit words. The Mylar "encased copper tabs and access lines."<ref name="encyc">{{cite book |last1=Kent (ed.) |first1=Allen |title=Encyclopedia of Library and Information Science: Volume 69 - Supplement 32 |date=2000 |publisher=CRC Press |isbn=0-8247-2069-5 |page=267 |url=https://books.google.com/books?id=1U_gOuKGFYYC&pg=PA267 |accessdateaccess-date=Dec 3, 2018}}</ref> A hole punched at a specific ___location removed the copper tab and encoded a zero, unpunched locations were read as ones.<ref name="encyc"/>

[[File:Ibm 360-30.jpg|thumb|IBM 360 Model 30 front panel and internal components]]

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The minimum memory needed to run DOS or TOS was 16&nbsp;KB.

TOS [[TOS/360|(Tape Operating System)]], as the name suggests, required a tape drive but no disk. It shared most of the code base<ref name=40Y.mem>{{cite newsgroup|url=https://groups.google.com/d/msg/alt.folklore.computers/RZA6FD27Tc0/-LoIXsOee7gJ|title=DOS/360: Forty years|author=Joe Morris|newsgroup=alt.folklore.computer|date=April 25, 2005|quote=Don't forget TOS, the bastard cousin of DOS. Either could be generated from the same set of distribution libraries...}}</ref> and some manuals<ref>{{cite web|url=http://www.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|date=October 1970|id=GC2ij-5030-8}}</ref><ref>{{cite web|url=http://www.bitsavers.org/pdf/ibm/360/dos/GC24-3465-8_DOS_and_TOS_Utility_Programs_R26.1_Aug73.pdf|title=DOS and TOS Utility Programs|date=August 1973|id=GC24-3465-8}}</ref> with IBM's DOS/360 and went through 14 releases. TOS was discontinued<ref>{{cite mailing list|url=https://www.mail-archive.com/[e-mail]/msg24371.html|author=Anne and Lynn Wheeler|title=Re: IBM 1401|date=May 28, 2009|mailinglistmailing-list=[e-mail]}}</ref>{{failed verification|date=January 2020}} when disk drives became more affordable.<ref>Computerworld,Sept.5,1977,p.40 - quotes an IBM task force report that referred to "price alone rather than by price/performance."</ref>

DOS [[DOS/360|(Disk Operating System)]] was a popular choice for the 360/30.<ref>Of those 360/30 and 360/40 machines still around in 1981/being replaced by 4300 systems, a Computerworld survey showed that DOS was what they ran/had run, May 25, 1981, p. 26</ref><ref>{{cite web|url=http://www.edwardbosworth.com/My3121Textbook_HTM/MyText3121_Ch03_V01.htm|title=Programming Assembler Language on the IBM Mainframes: An Introduction|at=Chapter 3 – The Heritage of the IBM System/360|author=Edward L. Bosworth}}</ref><ref>{{cite web|url=http://ed-thelen.org/comp-hist/ibm-360-30.html|title=IBM System 360, Model 30|author=Ed Thelen}}</ref><ref>{{cite web|url=http://www.highersystems.co.uk/ibm_360_30.html|title=IBM 360/30}}</ref>