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Guy Harris (talk | contribs) For the IBM System/370 Model 145, and pictures thereof, see IBM System/370 Model 145. |
Guy Harris (talk | contribs) →Operating systems: We already distinguish between the 155 and 155-II; the 155 only supported virtual-memory OSes if you upgraded it to a 155-II. Remove some extra stuff about MVS. |
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The '''IBM System/370 Model 155''' (and the [[IBM System/370 Model 165|Model 165]])<ref name=IBMarc.165>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3165.html|title=System/370 Model 165|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230729090329/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3165.html|archive-date=2023-07-29|url-status=dead}}</ref>
were jointly announced Jun 30, 1970<ref name=IBMarc.155>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3155.html|title=System/370 Model 155|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230516082850/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3155.html|archive-date=2023-05-16|url-status=dead}}</ref> as "designed for ... the Seventies." That same day [[IBM]] announced the 370/195.<ref
Since none of them came with [[virtual memory]], "which was to be a hallmark of the 370 line",<ref name="what-course-for-the-3081">{{cite news|newspaper=Computerworld|date=November 24, 1980|page=34|url=https://books.google.com/books?id=cKmJJd7R8PIC&pg=PA34|title=What Course for the 3081?}}</ref> some said about these early members of the [[IBM System/370]] family, especially about the 155 and 165, that they were not "the real 370 line."<ref name="what-course-for-the-3081" />
Three months later a fourth IBM System/370, the [[IBM System/370 Model 145|Model 145]], was announced.
The 370/155 was described as able to "run under [[DOS/360 and successors|DOS]]." Both the 155 and the larger 370/165 could "run under [[OS/360 and successors|OS/360]]." Being members of the System/370 family, the Model 155 and Model 165 were compatible with each other. Neither machine, as announced, could run a virtual memory operating system.▼
==Virtual memory==
The initially announced System/370 Models 155 and 165 systems did not support virtual memory.
In 1972 an upgrade option was announced "to provide the hardware necessary to operate in a virtual memory mode."<ref>{{cite news|newspaper=Computerworld|date=August 15, 1973|page=17|title=First IBM DAT Box Installed|url=https://books.google.com/books?id=T3qky0Z-gc0C&pg=PA17}}</ref> Unlike the [[IBM System/370 Model 145]], which as early as June 1971 included the hardware necessary to support virtual memory, and for which a [[microcode]] update from a floppy disk, adding support for virtual memory, was announced in 1972, the Model 155 and Model 165 needed expensive hardware additions - $200,000 for the 155 and $400,000 for the 165 - to add virtual memory capability. An upgraded 155 was known as an IBM System/370 Model 155-II.<ref>{{cite journal | author = A. Padegs | title = System/360 and Beyond | journal = IBM Journal of Research & Development | volume = 25 | issue = 5 | pages = 377–390 |date=September 1981 | publisher = IBM | doi = 10.1147/rd.255.0377}} – tables include model characteristics (Table 1) and announcement/shipment dates (Table 2). The S/370-155-II and -165-II are listed under the former but not the latter, because the upgraded systems were not formally announced as separate models. The "System/370 Advanced Function" announcement, including the -158 and -168, was the main public event.</ref>
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==Channels==
Channel 0 was a byte multiplexor channel, channel 1 to 5 were block multiplexor channels. Channel 0 and 1 were standard, channel 2 to 5 were optional upgrades.
==Operating systems==
▲The 370/155
A 370/155 upgraded to a 370/155-II, with support for virtual memory added, supported [[DOS/VS]] (DOS/360 with virtual storage), [[OS/VS1]] ([[OS/360 and successors#OS/MFT|OS/360 MFT]] with virtual storage), OS/VS2 Release 1 ([[OS/360 and successors#OS/MVT|OS/360 MVT]] with virtual storage), termed [[OS/VS2 (SVS)|SVS]] (Single Virtual Storage), and Release 2, termed [[MVS]] (Multiple Virtual Storage), and [[VM (operating system)|VM/370]].
==See also==
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