Programmed Data Processor

Series of computers made by Digital Equipment Corporation. PDP is an abbreviation for Programmable Data Processor -- 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 was aimed at a market who couldn't afford them.

Some of the PDP machines are related to each other; but most have little more in common than having been made by the same company.

Members of the PDP series include:

PDP-1: the original PDP. It had the first multiuser operating system. One of the first computer games, "Spacewar", was developed for this machine.
PDP-6: 36-bit timesharing machine. Was considered a mainframe, although small by today's standards
LINC LINC (Laboratory Instrument Computer): A 12-bit machine with a tiny instruction set. The LINC and the PDP-8 can be considered the first mini computers and perhaps the first personal computers as well. Unlike today's personal computers, the LINC sold for about $50,000. Interfaced well with laboratory experiments. Was designed by Wesley Clark at Lincoln Labs, Massachusetts as a smaller version of the TX-0/TX-1 computers, but manufactured by Digital. Not in the PDP family, but important as progenitor of the PDP-12
PDP-8: 12-bit machine with a tiny instruction set. The first successful "personal computer", many were purchased by schools; 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: ???
PDP-10: 36-bit timesharing machine. Slightly elaborated form of PDP-6.
PDP-11: 16-bit machine. Also LSI-11, primarily for embedded systems. The VAX series was descended from it.
PDP-12: Descendant of the LINC-8
PDP-14: An industrial controller

The PDP-8 and PDP-11 were the most popular of the PDP series of machines.