PDP
PDP is an abbreviation for
Programmable Data Processor; they were a series of
computers, several of them ground-breaking and very influential, made by
Digital Equipment Corporation. They were given that name because at the time of their introduction, computers had a reputation of being large and expensive machines, and the PDP machines were aimed at a market which couldn't afford the larger computers.
Some of the PDP machines are related to each other in families; but most have little more in common than having been made by the same company.
PDP Series
Members of the PDP series include:
- PDP-1: The original PDP, an 18-bit machine used in early time-sharing operating system work, and prominent in early hacker culture. One of the first computer games, Spacewar, was developed for this machine.
- PDP-4: Supposed to be a slower, cleaper alternative to the PDP-1, but not commercially successful; all later PDP 18-bit machines were based on its instruction set.
- PDP-6: 36-bit timesharing machine. It was considered a mainframe, although small by today's standards.
- PDP-7: Replacement for the PDP-4; DEC's first wire-wrapped machine. The first version of Unix was for this machine.
- PDP-8: 12-bit machine with a tiny instruction set; DEC's first wildly successful computer. The first successful "personal computer", many were purchased by schools, university depts, and research labs; also used in the DECmate word processor and the VT-78 workstation.
- LINC-8: A hybrid of the LINC and PDP-8 computers; two instruction sets. Progenitor of the PDP-12.
- PDP-9: Successor to the PDP-7, DEC's first micro-programmed machine.
- PDP-10: 36-bit timesharing machine, and fairly successful over several different models. The instruction set was a slightly elaborated form of that of the PDP-6.
- PDP-11: 16-bit machine, widely regarded as the best 16-bit instruction set ever created, and another huge hit for DEC. Also the LSI-11, primarily for embedded systems. The VAX series was descended from it.
- PDP-12: Descendant of the LINC-8.
- PDP-14: A 12-bit machine intended as an industrial controller.
- PDP-15: DEC's final 18-bit machine.
Related computers:
- LINC (Laboratory Instrument Computer), originally designed by MIT's Lincoln Labs, some built by DEC. Not in the PDP family, but important as progenitor of the PDP-12.
The LINC and the PDP-8 can be considered the first minicomputers, and perhaps the first personal computers as well. The PDP-8 and PDP-11 were the most popular of the PDP series of machines.
Digital never made a PDP-20, although the term was sometimes used for a PDP-10 running TOPS-20.
Further Reading
- C. Gordon Bell, J. Craig Mudge, John E. McNamara, Computer Engineering: A DEC View of Hardware Systems Design (Digital, 1979)
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