PDP-11/03

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PDP-11/03
Pdp11-03.JPG
PDP-11/03
Manufacturer: Digital Equipment Corporation
Architecture: PDP-11
Year Introduced: 1975
Bus Architecture: QBUS

The PDP-11/03, which initially shipped with the new LSI-11 CPU, marked a major change in the PDP-11 family in two ways:

  • it was the first PDP-11 to essentially use a microprocessor (although the LSI-11 chip set was 4 chips, not 1, it was effectively a microprocessor);
  • it was the first to use a new system bus, the QBUS, which used fewer lines (thus allowing cards which plugged into QBUS backplanes to have fewer contact fingers), thereby reducing costs.

hampage.hu

Quoting:

1975. With the use of LSI semiconductor technology (the LSI-11 and LSI-11/2 processor), it was a compact implementation of the -11 architecture. It was limited though, to 32KW memory, only one processor operating mode, and limited floating-point instructions (the FIS). Available options: CIS, WCS, EIS/FIS.
The /03 used the new LSI bus, later known as the QBUS, and was aimed at the low-end market, as the successor of the /05. The slowest of the -11s (one third of the 11/20's performance).

A PDP-11/03 was also used as the diagnostic and control unit for the VAX-11/780's CPU; it would bootstrap the system.

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