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Manufacturer | International Business Machines Corporation (IBM) |
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Product family | System/370 |
Release date | June 30, 1970 |
Discontinued | December 23, 1977 |
Website | Official website IBM Archives |
The IBM System/370 Model 165 (and the Model 155 [1] ) were jointly announced June 30, 1970 [2] as "designed for ... the Seventies." That same day IBM announced the 370/195. [3] They were the first three models of the IBM System/370 line of computers.
Since none of them came with virtual memory, "which was to be a hallmark of the 370 line", [4] some said about these early members of the IBM System/370 family, especially about the 165 and 155, that they were not "the real 370 line." [4]
Three months later a fourth IBM System/370, the Model 145, was announced.
The initially announced System/370 Models 165 and 155 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." [5] 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 165 was known as an IBM System/370 Model 165-II. [6]
The 370/165, when equipped with the appropriate compatibility feature, [7] [8] [9] [10] with the use of an emulator program permits running
The IBM 7070/7074 Compatibility Feature allowed the 165 to "run 7070 and 7074 programs at speeds that, in general, equal or exceed those of the original systems" [7] and yet "not affect normal operation of System/370." [7] : p.5
Although the joint 155/165 announcement [2] did not have the word virtual, there were multiple references to (physical) memory, storage (both main memory and disk storage), and cache memory under the name "buffer".
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.
The 370/165 supported both DOS/360 and OS/360. [1] Being members of the System/370 family, the Model 155 and Model 165 were compatible with each other. Lacking virtual memory support, neither machine, as announced, could run a virtual memory operating system.
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The IBM System/370 Model 145 was announced September 23, 1970, three months after the 155 and 165 models. It was the fourth member of the IBM System/370 line of computers, and was the first IBM computer to use semiconductor memory for its main memory instead of magnetic core memory. It was described as being five times faster than the IBM System/360 Model 40. First shipments were scheduled for late summer of 1971.
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