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IBM System/370 Model 145

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IBM System/370 Model 145 system console

The IBM System/370 Model 145 was announced Sep 23, 1970,[1] three months after the 155 and 165[2] models.

New capabilities

As with all IBM 370 systems, the 145 could "out of the box" provide support for for an architecture described as "extended, but not redesigned, for System/370."[2].

The 370 introduced some new instructions, such as

  • MOVE CHARACTER LONG (MVCL) and
  • COMPARE CHARACTER LONG (CLCL),

thereby permitting operations on up to 2^24-1 bytes (16 MB), vs. the 256-byte limits on the 360's MVC and CLC.[3][4], but lacked a DAT (Dynamic Address Translation) box.

Virtual memory

Some said about the 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."[5]

Unlike the earlier Model 155 and 165 systems, for which an upgrade to Virtual memory required the purchase of expensive hardware[6][7], the 145's customers had two advantages:

  • 370/145 customers did not have to wait as long for this lack of virtual memory to be remedied[8]
  • there was no need to buy extra hardware: An upgrade to the 145's microcode through a new microcode floppy disk [9] via floppy drive[10][11] enabled virtual memory capability.

VM/CMS

Upon gaining virtual memory capability via a microcode update, the 145 could now support the VMF (Virtual Machine Facility) and VM/CMS, a time-sharing system.

See also

References

  1. ^ "System/370 Model 145". IBM Archives. IBM.
  2. ^ a b "System/370 Model 165". IBM Archives. IBM.
  3. ^ http://faculty.cs.niu.edu/~byrnes/csci360/notes/360ex.htm
  4. ^ http://research.microsoft.com/en-us/um/people/ gbell/tcmwebpage/timeline/chap51_ibm370_cs2.pdf
  5. ^ Computerworld, Nov. 24, 1980, p.34, in an article that looked back, from the vantage point of the IBM 3081.
  6. ^ Computerworld, Nov. 24, 1980, p.34
  7. ^ a Dynamic Address Translation (DAT) box
  8. ^ June 1971 vs. Aug. 1972
  9. ^ IBM Maintenance Library 3145 Processing Unit Theory - Maintenance. IBM. pp. CPU 117–129. SY24-3581-2
  10. ^ https://books.google.com/books?id=pGJK0ayV3S8C Computerworld,July 5, 1976
  11. ^ www.computerhistory.org/timeline/memory-storage
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