Difference between revisions of "Interface Message Processor"
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The IMPs were Honeywell DDP-516 'ruggedized' [[minicomputer]]s, with added special high-speed modem interfaces, and asynchronous bit-serial Host interfaces. Later, other variant minicomputers were also used; the Honeywell DDP-316 (the non-ruggedized version of the 516), the Pluribus, and the [[BBN]] C/30 (which first had [[microcode]] which emulated the Honeywell machines, later an updated "native mode" microcode exposing the full 20-bit hardware). | The IMPs were Honeywell DDP-516 'ruggedized' [[minicomputer]]s, with added special high-speed modem interfaces, and asynchronous bit-serial Host interfaces. Later, other variant minicomputers were also used; the Honeywell DDP-316 (the non-ruggedized version of the 516), the Pluribus, and the [[BBN]] C/30 (which first had [[microcode]] which emulated the Honeywell machines, later an updated "native mode" microcode exposing the full 20-bit hardware). | ||
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==External links== | ==External links== | ||
* [http://walden-family.com/impcode/ Resurrection of the 1973 IMP code] - While focused on the retrieval, and running under a simulator, of the original IMP code, this site contains much other IMP-related material too (manuals, etc) | * [http://walden-family.com/impcode/ Resurrection of the 1973 IMP code] - While focused on the retrieval, and running under a simulator, of the original IMP code, this site contains much other IMP-related material too (manuals, etc) | ||
| − | ** [https://walden-family.com/impcode/imp-hardware.pdf Intermodem Processor System] - Honeywell manual covering much of the custom IMP hardware | + | ** F.E. Heart, R.E. Kahn, S.M. Ornstein, W.R. Crowther, and D.C. Walden, [http://www.walden-family.com/public/1970-imp-afips.pdf The interface message processor for the ARPA computer network], Proceedings AFIPS, 1970 SJCC, Vol. 36, pp. 551-567.** [https://walden-family.com/impcode/imp-hardware.pdf Intermodem Processor System] - Honeywell manual covering much of the custom IMP hardware |
** [https://walden-family.com/impcode/imp-code.pdf The Arpanet IMP Program: Retrospective and Resurrection] | ** [https://walden-family.com/impcode/imp-code.pdf The Arpanet IMP Program: Retrospective and Resurrection] | ||
* [http://www.chiappa.net/~jnc/tech/arpanet.html ARPANET Technical Information] | * [http://www.chiappa.net/~jnc/tech/arpanet.html ARPANET Technical Information] | ||
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[[Category: Networking]] | [[Category: Networking]] | ||
Revision as of 14:31, 27 October 2021
The Interface Message Processor (or IMP, as they were universally known) was the packet switch which the ARPANET was made out of; the IMPs were connected to each other via high-speed dedicated point-point telephone links, connected to the IMPs via a modem. All ARPANET hosts connected to an IMP, using the Host-to-IMP Protocol.
A message from one Host to another was sent via the source Host's IMP, then routed through some number (possibly zero) intermediate IMPs, then through the destination Host's IMP (possibly the same IMP as the first one, in which case the message never went over a telephone line), on to the destination Host.
The IMPs were Honeywell DDP-516 'ruggedized' minicomputers, with added special high-speed modem interfaces, and asynchronous bit-serial Host interfaces. Later, other variant minicomputers were also used; the Honeywell DDP-316 (the non-ruggedized version of the 516), the Pluribus, and the BBN C/30 (which first had microcode which emulated the Honeywell machines, later an updated "native mode" microcode exposing the full 20-bit hardware).
External links
- Resurrection of the 1973 IMP code - While focused on the retrieval, and running under a simulator, of the original IMP code, this site contains much other IMP-related material too (manuals, etc)
- F.E. Heart, R.E. Kahn, S.M. Ornstein, W.R. Crowther, and D.C. Walden, The interface message processor for the ARPA computer network, Proceedings AFIPS, 1970 SJCC, Vol. 36, pp. 551-567.** Intermodem Processor System - Honeywell manual covering much of the custom IMP hardware
- The Arpanet IMP Program: Retrospective and Resurrection
- ARPANET Technical Information
