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Guy Harris (talk | contribs) Some said" means "the author of the Computerworld column said", so use it as a reference. Remove a non-reference footnote whose relevance is not clear (other than that, as noted in the "Virtual memory" section, those two models, unlike all subsequent models, needed an expensive hardware upgrade to support VM). The "not real 370s" applied to the 155 and 165, not the 145, which already had the hardware necessary for VM, and only needed a microcode update. |
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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[[File:IBM_magnetic_disk_drives_3330+3333.png|thumb|The IBM 3330 <br>Direct Access Storage Facility, <br>code-named Merlin, was introduced in June 1970 for use with the IBM System/370. Its removable disk packs could hold 100 MB]]
The '''IBM System/370 Model 155''' (and the [[IBM System/370 Model 165|Model 165]])<ref name=IBMarc.165>{{cite web|url=https://www
were jointly announced Jun 30, 1970<ref name=IBMarc.155>{{cite web|url=https://www
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" />
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Three months later a fourth IBM System/370, the [[IBM System/370 Model 145|Model 145]], was announced.
==
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
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.▼
▲Unlike the [[IBM System/370 Model 145]], which as early as June 1971 could have virtual memory capability added to it with a simple [[microcode]] update from a floppy disk, 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, and even this had to wait until 1972, at which time their 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>
==Physical memory==
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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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