IBM System/370 Model 168
ManufacturerInternational Business Machines Corporation (IBM)
Product familySystem/370
Release dateAugust 2, 1972 (1972-08-02)
DiscontinuedSeptember 15, 1980
Memoryup to eight megabytes of integrated monolithic processor storage
WebsiteOfficial website IBM Archives

The IBM System/370 Model 168 and Model 158[1] were both announced on August 2, 1972.[2] Prior 370 systems had not "offered virtual storage capability, which was to be a hallmark of the 370 line," and some said that the 168 and 158 were the first "real 370" products.[3] By contrast, "in 1972, the System/370 Advanced Function was released and had new Address Relocation Hardware and now supported four new operating systems (VM/370, DOS/VS, OS/VS1, OS/VS2)."[4]

The 158 and 168 were withdrawn on September 15, 1980.

Features

Main memory

Main memory, which was four-way doubleword interleaved, could be 1 to 8 megabytes, with offerings selectable in increments of one megabyte.[5]

The Model 168 used semiconductor memory, rather than the magnetic-core memory used by the 370/165[5] introduced 2 years prior, resulting in a system that was faster and physically smaller than a Model 165.[5]: pp.3–5 

System console

The newly introduced IBM 3066 Model 2 System console

  • included a light pen[NB 1]
  • replaced "most switch, pushbutton, and indicator functions"[NB 2][5]: p.32 
  • as with the 165's Model 1, had a microfiche document viewer,[NB 3] a feature introduced for the 360/85's console.[NB 4]

A console printer (up to 85 characters per second) to provide hard copy was optional when the console was in display mode, and required when it was in printer-keyboard mode.

Disk storage

The newly introduced Model 11 of IBM's 3330 family of disk drives, featuring removable disk packs, has double the capacity of the prior 100-megabyte offerings.[NB 5][NB 6] It can't be attached to a 370/165.[5]: p.94 

Multiprocessing

Both the 370/168 and the 370/158 had MP (multiprocessing) models that offered "tightly coupled multiprocessing.[1]

The 168 was described[2] as having "two types of multiprocessing support" since it also offered attaching a second processing unit, an IBM 3062 Attached Processing Unit, which lacked access to Input/Output channels.

Extended precision floating-point

This feature adds support for 128-bit "hexadecimal" floating-point operands. It is standard on all 165 and 168 models, and is an "Optional (no-charge)" feature on the 370/158.[5]: p.137 

Emulation

The optional IBM 7070/7074 Compatibility Feature allowed the 168 to "run 7070 and 7074 programs at speeds that, in general, equal or exceed those of the original systems"[6] and yet "not affect normal operation of System/370."[5]: p.139 [6]: p.5 

Other listed options are:

  • 7080 Compatibility
  • 709/7090/7094 II Compatibility

There is a limitation, however, described as:
"Note: Compatibility features are mutually exclusive."

System/370 Extended Facility

This optional facility of the 168-3 provides support for MVS/System Extensions (MVS/SE) and for the later MVS/System Product (MVS/SP).[7]

168-1 & 168-3

The Third (June 1975) edition of IBM's 168 Guide introduced the 168-3.
"There are two versions of the Model 168: the Model 1 and the Model 3."[5]: preface 

IBM referred to the System/370 Model 168-3 as "the company's ... flagship."[NB 7]

The 168-3 CPU's internal performance has been described as 5–13% faster than the 168-1.[5]: p.125 

See also

Notes

  1. ↑ Although only the 158 announcement mentioned the light pen, the 168's manual says "light pen is standard."
  2. ↑ among the few retained: "system clear" and "cooling reset alarm"
  3. ↑ the online manual has an extra dot: "d.ocument"
  4. ↑ the 360/85 article includes a photo of same
  5. ↑ It has the same number of platters but double the number of data cylinders.
  6. ↑ Similar to the Massbus / DEC RP05/RP06 100 MB/200 MB capacities and number of cylinders.
  7. ↑ https://www-03.ibm.com/ibm/history/exhibits/3033/3033_intro.html, when comparing it and the then-new IBM 3033.

References

  1. 1 2 "System/370 Model 158". IBM Archives. IBM. 23 January 2003.
  2. 1 2 "System/370 Model 168". IBM Archives. IBM. 23 January 2003.
  3. ↑ "What Course for the 3081?". Computerworld. November 24, 1980. p. 34.
  4. ↑ Marshall, David; Reynolds, Wade A.; McCrory, Dave (17 May 2006). Advanced Server Virtualization. p. 8. ISBN 1420013165.
  5. 1 2 3 4 5 6 7 8 9 "A Guide to the IBM System/370 Model 168" (PDF). IBM. June 1975.
  6. 1 2 "7070/7074 Compatibility Feature for IBM System/370 Models 165, 165 II, and 168" (PDF). IBM. June 1973. GA22-6958-1.
  7. ↑ "IBM System/370 Extended Facility" (PDF). IBM System/370 Extended FacilitY (PDF). IBM. January 1978. p. 4. GA22-7072-0. The IBM System/370 extended facility or feature is available on all processor complexes and some models of System/370. Developed to support the internal structure of the MVS control program, this facility enhances the capabilities and performance of the MVS system when it is used with the MVS/System Extensions program product (program No. S740-XE1).
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