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Attached Support Processor

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Attached Support Processor (ASP) is an implementation of loosely-coupled multiprocessing for IBM's OS/360 operating system.[1][2]

ASP evolved from the design of the 7094/7044 Direct Coupled System, using data channel to data channel communication. By attaching an IBM 7044 as a peripheral processor throughput was more than doubled.

ASP was introduced in March 1967, and initially allowed connection of two System/360 computers via a channel-to-channel adapter (CTCA).[3]

As initially defined an ASP system consisted of a large System/360 computer, a Model 50, 65, or 75 running OS/360, called the main processor, and a smaller System/360, Model 40 or larger, called the support processor, running the ASP supervisor as a single task under OS/360 PCP (Primary Control Program). The support processor performed functions such as printing, card reading and punching, freeing the main processor to run the application workload.[2]

The main processor was configured identically to a "stand-alone processor operating under OS/360, except that the channel-to-channel adapter replaces the normal system input and output devices." The support processor was a minimum of a Model 40 G (G indicates memory size of 128KB) with two selector channels, a 1052 console typewriter, a 2540 card read/punch, a 1403 printer, and three 2311 disk drives. It was recommended that the support processor have access to one 2400-series tape drive for support.

The OS version on the main processor was modified to be able to overlay itself with the 7090/94 emulator program when an emulator job was to be run, and the emulator program would similarly overlay itself with OS/360 when done, to process emulated 709x jobs intermixed with standard 360 jobs.[2]

With the introduction of System/370 ASP was renamed Job Entry Subsystem 3 (JES3) and is still in use as of 2014.

References

  1. ^ "Representative ASP Installation". Computerworld. September 13, 1967. Retrieved February 7, 2013.
  2. ^ a b c IBM Corporation (1967). Catalog of Programs for IBM System/360 August 1967 (PDF).
  3. ^ Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems. MIT Press. p. 710. ISBN 0262161230.

See also

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