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IBM System/360 Model 65

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The Model 65 of the IBM System/360 family of mainframe computers, announced April of 1965, replaced two models announced one year prior [1] but never built [2].

Models

System/360 Model 65 operators's console.

"There are five models of the Model 65." [3] They differ only in their amount of main storage, and they're termed G65, H65, I65, IH65 and J65, configured with 128K, 256K, 512K, 768K or 1M of Core memory, respectively[4].

The Model 65 [5] was available in a dual-CPU offering.

Multi-processing (Dual-CPU) systems are comprised of two I65s, IH65s or J65s, and "the main storage of each processing unit is accessible to the other."[6]

Relative Performance

The performance of the Model 65 was over triple that of a 360/50, whereas the Model 75, the next step up, was less than double that of a 360/65 [7].

Features

Main memory in the Model 65[8][9]can be interleaved, for faster access to memory.

A compatibility feature exists to permit emulation of certain older models [10]. While other 360 Models also have compatibility [11], these are for higher end prior generation machines [12].

Systems software

Although the cover of IBM's MVT Guide[13] indicates that, with enough memory, even a 360/40 could run this[14] top-of-the-line operating system[15], even a 360/50 was unlikely to have the minimum required memory [16] and CPU power. For a 360/65, however, MVT was a fairly typical choice of operating system[17]. [18].


A special version of MVT was needed for the multi-process (dual CPU) Model, called MP65[19] [20].

Time-sharing

Just as the IBM System/360 Model 50 used CALL/OS for Time-sharing, time-sharing on a 360/65 (or larger) System could be done using TSO, IBM's Time Sharing Option[21].

also see

References

  1. ^ the models 60 & 62: [[IBM System/360#Table of System/360 models|Time line of S/360 models
  2. ^ http://www.computerhistory.org/revolution/mainframe-computers/7/161
  3. ^ page 5, http://bitsavers.org/pdf/ibm/360/funcChar/A22-6884-3_360-65_funcChar.pdf
  4. ^ K = 1,024 bytes, e.g. the G65's 128K = 131,072 bytes
  5. ^ like the model 67; per details in IBM System/360#Models
  6. ^ Func.Char manual
  7. ^ based on CPU performance and Bandwidth numbers in Time line of S/360 models
  8. ^ Func.Char,p.8
  9. ^ and also the Model 75; http://www.faqs.org/qa/qa-16398.html
  10. ^ e.g. A27-2716, Special Feature Description, 7080 Compatibility Feature for System/360 Model 65. Other 360/65 compatibility modes are described in A27-2715 and A27-2717.
  11. ^ e.g. 1401 emulation on the 360/30 & 40
  12. ^ 7040,7044,7070,7074,7080, 7090,7094
  13. ^ GC28-6720, http://bitsavers.trailing-edge.com/pdf/ibm/360/os/R21.7_Apr73/GC28-6720-5_MVT_Guide_Rel_21.7_Aug74.pdf
  14. ^ for its day
  15. ^ https://en.wikipedia.org/wiki/OS/360_and_successors#MVT
  16. ^ http://www.os390-mvs.freesurf.fr/mvs360.htm
  17. ^ a 360/40 typically ran IBM's DOS operating system, and a 360/50 typically ran MFT
  18. ^ see http://www.textfiles.com/bitsavers/pdf/ibm/360/mvt/GC28-6551-16_OS_Storage_Estimates_Apr73.pdf
  19. ^ https://www.scribd.com/document/82582665/Mainframes-Terminology
  20. ^ it used special CPU-to-CPU/Multisystem mode instructions, such as Write Direct
  21. ^ GC28-6698, Time Sharing Option Guide
  22. ^ System/360#Remaining machines
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