Programmed Data Processor Totally Explained

Everything about Programmed Data Processor totally explained

Programmed Data Processor (abbreviated PDP) was the name of a series of minicomputers, several of them ground-breaking and very influential, made by Digital Equipment Corporation. The name 'PDP' intentionally avoided the use of the term 'computer' because at the time of the first PDPs, computers had a reputation of being large, complicated, and expensive machines, and the venture capitalists behind Digital (esp. Georges Doriot) wouldn't support Digital's attempting to build a "computer". The word "minicomputer" wasn't invented yet. So instead, Digital used their existing line of logic modules to build a Programmable Data Processor and aimed it at a market which couldn't afford the larger computers. The various PDP machines can generally be grouped into families based on word length. With the notable exception of the 16-bit PDP-11, the various architectures all show strong similarities, with the 36-bit PDP-6 and PDP-10 architecture being the most elaborate version.

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-2: An unbuilt 24-bit design.

PDP-3: First 36-bit machine DEC designed, though DEC didn't offer it as a product. The only PDP-3 was built by a customer (alleged to be an intelligence agency) in 1960. Architecturally it was essentially a PDP-1 stretched to 36-bit word width. ;PDP-4: Supposed to be a slower, cheaper alternative to the PDP-1, but not commercially successful; all later 18-bit PDP machines were based on its instruction set.

PDP-5: DEC's first 12-bit machine. Introduced the instruction set later used in the PDP-8. ;PDP-6: 36-bit timesharing machine. Very elegant architecture. It was considered a large minicomputer or a mainframe.

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 major commercial success. Many were purchased by schools, university departments, and research laboratories. Later models were also used in the DECmate word processor and the VT-78 workstation. It is reported that Edson de Castro, who had been a key member of the design team, left to form Data General when his design for a 16-bit successor to the PDP-8 was rejected in favour of the PDP-11; the "PDP-X" did NOT resemble the Data General Nova, although that's a common myth.

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: The archetypal minicomputer; a 16-bit machine and another commercial success for DEC. (Also the LSI-11, primarily for embedded systems). The 32-bit VAX series was descended from and mostly backwards-compatible with it. The 16-bit PDP-11 instruction set has been very influential, with processors ranging from the Motorola 68000 to the Renesas H8 and Texas Instruments MSP430, inspired by its highly orthogonal, general-register oriented instruction set and rich addressing modes. The PDP-11 family was incredibly long-lived, spanning 20 years and many different implementations and technologies.

PDP-12: Descendant of the LINC-8. See LINC and PDP-12 User Manual. ;PDP-13: Designation wasn't used, apparently due to superstition.

PDP-14: A 1-bit machine intended as an industrial controller (PLC). Latter versions (for example, the PDP-14/30) were based on PDP-8 physical packaging technology. I/O was line voltage. ;PDP-15: DEC's final 18-bit machine. Their only 18-bit machine constructed from TTL integrated circuits rather than discrete transistors. Later versions of the system were referred to as the "XVM" family.

PDP-16: A "roll-your-own" sort of computer using Register Transfer Modules, mainly intended for industrial control systems with more capability than the PDP-14. The PDP-16/M was introduced as a standard version of the PDP-16.

Related computers

TX-0 designed by MIT's Lincoln Laboratory, important as influence for DEC products including Ben Gurley's design for the PDP-1
LINC (Laboratory Instrument Computer), originally designed by MIT's Lincoln Laboratory, 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 (officially known as a DECSYSTEM-20).
SM EVM series of computers in the USSR
DVK personal computers series are PDP clones developed in USSR in 70s.
Elektronika BK
UKNC

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