IBM System/370 Model 155: Difference between revisions

Revision as of 04:34, 12 February 2021

Revision as of 21:06, 29 May 2021

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==Limitations==

Some said about these early members of the [[IBM System/370]] family, looking back, that they were not "the real 370 line" because

"neither offered virtual storage capability, which was to be a hallmark of the 370 line."<ref name="what-course-for-the-3081">{{cite newspapernews|newspaper=Computerworld|date=November 24, 1980|page=34|url=https://books.google.com/books?id=cKmJJd7R8PIC&pg=PA34#v=onepage&q&f=false|title=What Course for the 3081?}}</ref>

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.

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===Upgrade option===

In 1972 an upgrade option was announced "to provide the hardware necessary to operate in a virtual memory mode."<ref>{{cite newspapernews|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#v=onepage&q&f=false}}</ref>

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}} &ndash; 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>