IBM System/370 Model 155: Difference between revisions

Revision as of 08:32, 28 December 2016

Revision as of 22:33, 11 January 2017

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and https://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3195.html</ref> They were the first three models of the [[IBM System/370]] line of computers.

Three months later a fourth IBM System/370, the [[IBM System/370 Model 145|Model 145]], was announced. Since none of them came with [[virtual memory]], "which was to be a hallmark of the 370 line"<ref>{{cite newspaper|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> some said about these early members, of the [[IBM System/370]] family, especially about the 165 & 155, that they were not "the real 370 line."<ref group="NB">The 195 was noted as "at the time of its introduction, ... IBM's most powerful computing system" and the 145's [[microcode]] could be upgraded from a floppy disk. By contrast, the 155 & 165 needed a hardware addition priced at $200,000 and $400,000 respectively</ref>

==Limitations==

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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>

==Physical Memory==

Although the joint 155/165 announcement<ref name=IBMarc.165/> did not have the word virtual, there were multiple references to (physical) memory, storage (both main memory and disk storage), and [[buffer]]s.

The 155 had seven main memory choices, ranging from 256K to 2 MB; the 165: five possibilities, from 512K to 3 MB. Both models were described as having "a very high-performance buffer storage backed by a large" main memory.

==See also==