Difference between revisions of "Interface Message Processor"

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(Native mode C/30.)
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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.
 
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' [[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 had [[microcode]] which emulated the Honeywell machines).
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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).
  
 
==External links==
 
==External links==

Revision as of 19:15, 24 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