Programmed data processor

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PDP-1 (the actual computer is in the background)
PDP 8 / E

Programmed Data Processor ( PDP ) is the name for many different computers made by Digital Equipment Corporation (DEC, today HP ). PDP is an abbreviation for Programmable Data Processor or Programmed Data Processor .


In order not to enter into direct competition with the powerful IBM , DEC avoided the word computer in the name of their computers in the 1960s . Instead, the company called their devices a programmable data processor . The PDP computers were numbered starting with the small PDP-1 (18 bit word length, 4096 memory words by default) in the order of their development (there are still rumors about the lack of PDP-2 and PDP-3). As a result, related systems never have consecutive numbers. Between 1959 and 1982 there were a total of more than 60 PDP models, which were spread over four system families and which in some cases also competed with each other:

  • the 18-bit family with PDP-1, PDP-4, PDP-7, PDP-9 and PDP-15
  • the 12-bit family with PDP-5, PDP-8, PDP-12, PDP-14 and PDP-16
  • the 36-bit family with PDP-6 and PDP-10
  • the 16/32-bit family with PDP-11 and VAX

There were many variants of the particularly successful PDP computers, e.g. B. PDP-8 : -8 / S, -8 / I, -8 / L, -8 / E, -8 / M, -8 / A.

The best known and most successful PDP was the PDP-11 .

Many PDPs were relatively inexpensive (the PDP-8 was available for less than US $ 20,000 ) and quickly found use in universities and as process computers, for example in the computerization of AT & T's American telephone network . At the other end of the price spectrum were the mainframe 36-bit computers PDP-6 and PDP-10 , which could cost several million US $ with the appropriate configuration.

An exemplary application of the PDP-8 in the history of technology is Olympia Multiplex 80 in the 1970s.

The PDPs were classic at first; H. from discrete components such. B. transistors built, then from integrated TTL circuits, later DEC went over to integrate the processors on an IC (T11, J11).

In addition to the increasing integration of the components, the connection technology also experienced considerable progress. The joining plane between the printed cards was initially from thousands of individual winding connections (engl. Wire Wrap ). As a significant advance, the so-called omnibus (a special version of a bus (data processing) ) was introduced as a replacement for the first time with the PDP-8 / E version , which also allowed a flexible, modular expansion of the system with additional components. The Swiss project manager for the development of the PDP-8 / E has published a report on this.

The significantly higher packing density then made it possible to accommodate a complete PDP-11 on a Q-Bus card and to build multiprocessor systems with these PDP-11s. Under the name MicroPDP, DEC launched a series of PDP-11s as desktop (personal) computers in which these processors were also used. In the early 1980s, a MicroPDP replica was produced in the Soviet Union under the name Elektronika BK-0010 .

Models (selection)

Operating systems

The following operating systems ran on PDP computers:


  • Computer Engineering, A DEC View of Hardware Systems Design, ISBN

Web links

Commons : Programmed Data Processor  - collection of images, videos and audio files

Individual evidence

  1. Pedigree of PDP computers
  2. ↑ Field report project manager PDP-8 / E development