Programmed Data Processor

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Programmed Data Processor

Programmed Data Processor (abbreviated PDP) was the name of a series of minicomputer

Minicomputer

A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems ....
s made by Digital Equipment Corporation

Digital Equipment Corporation

Digital Equipment Corporation was a pioneering United States company in the computer industry. It is often referred to within the computing industry as DEC ....
. 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

Georges Doriot

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Programmed Data Processor (abbreviated PDP) was the name of a series of minicomputer

Minicomputer

Digital Equipment Corporation

Georges Doriot

Georges F. Doriot was one of the first American venture capitalists. In 1946, he founded American Research and Development Corporation, the first publicly owned venture capital firm....
) wouldn't support Digital's attempting to build a "computer". The word "minicomputer" was not 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

PDP-11

The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s. Though not explicitly conceived as successor to DEC's PDP-8 computer in the Programmed Data Processor series of computers , the PDP-11 replaced the PDP-8 in many Real-time computing....
, the various architectures all show strong similarities, with the 36-bit PDP-6

PDP-6

The PDP-6 was a computer model developed by Digital Equipment Corporation in 1963. It was influential primarily as the prototype for the later PDP-10; the instruction sets of the two machines are almost identical....
and PDP-10

PDP-10

The PDP-10 was a mainframe computer manufactured by Digital Equipment Corporation from the late 1960s on; the name stands for "Programmed Data Processor model 10"....
architecture being the most elaborate version.

PDP series

Members of the PDP series include: PDP-1

PDP-1

The PDP-1 was the first computer in Digital Equipment Corporation's Programmed Data Processor series and was first produced in 1960. It is famous for being the computer most important in the creation of Hacker culture, at Massachusetts Institute of Technology, Bolt, Beranek and Newman and elsewhere....
: The original PDP, an 18-bit

18-bit

Possibly the most well-known 18-bit computer architectures are the PDP-1, PDP-4, PDP-7, PDP-9 and PDP-15 minicomputers produced by Digital Equipment Corporation from 1960 to 1975....
machine used in early time-sharing

Time-sharing

Time-sharing refers to sharing a computing resource among many users by Computer multitasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major historical shift in the history of computing....
operating system

Operating system

An operating system is an interface between hardware and applications; it is responsible for the management and coordination of activities and the sharing of the limited resources of the computer....
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 did not offer it as a product. The only PDP-3 was built by the CIA's Scientific Engineering Institute (SEI) in Waltham, MA to process radar cross section

Radar cross section

Radar cross section is a measure of how detectable an object is with a radar. When radar waves are beamed at a target, only a certain amount is reflected back....
data for the Lockheed A-12 reconnaissance aircraft 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

Instruction set

An instruction set is a list of all the instruction , and all their variations, that a processor can execute.Instructions include:* Arithmetic such as add and subtract...
. One customer of these early PDP machines was Atomic Energy of Canada. The installation at Chalk River, Ontario included an early PDP-4 with a display system and a new PDP-5 as interface to the research reactor instrumentation and control. PDP-5: DEC's first 12-bit

12-bit

Possibly the best-known 12-bit CPU is the PDP-8 and its relatives, produced in various incarnations from August 1963 to mid-1990. Many Analog-to-digital converters have a 12-bit resolution....
machine. Introduced the instruction set later used in the PDP-8. PDP-6

PDP-6

Minicomputer

Mainframe computer

Mainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, Enterprise Resource Planning, and financial transaction processing....
. PDP-7

PDP-7

The Digital Equipment Corporation PDP-7 is a minicomputer produced by Digital Equipment Corporation. Introduced in 1965, the first to use their Flip Chip technology, with a cost of only $72,000 USD, it was cheap but powerful....
: Replacement for the PDP-4; DEC's first wire-wrapped machine. The first version of Unix

Unix

Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
was for this machine. PDP-8

PDP-8

The PDP-8 was the first successful commercial minicomputer, produced by Digital Equipment Corporation in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date....
: 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

DECmate

DECmate was the name of a series of PDP-8-compatible computers produced by the Digital Equipment Corporation in the early 1980s. All of the models used an Intersil or Harris 6100 6120 microprocessor which emulated the 12-bit DEC PDP-8 CPU....
word processor

Word processor

A word processor is a computer Application software used for the production of any sort of printable material.Word processor may also refer to an obsolete type of stand-alone office machine, popular in the 1970s and 80s, combining the keyboard text-entry and printing functions of an electric typewriter with a dedicated computer for th...
and the VT-78 workstation

Workstation

A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems....
. It is reported that Edson de Castro, who had been a key member of the design team, left to form Data General

Data General

Data General was one of the first minicomputer firms from the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation....
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

Data General Nova

The Data General Nova was a popular 16-bit minicomputer built by the United States company Data General starting in 1969. The Nova was packaged into a single rack mount case and had enough power to do most simple computing tasks....
, although that is a common myth. LINC-8

LINC-8

LINC-8 was the name of a minicomputer manufactured by Digital Equipment Corporation between 1966 and 1969. It combined a LINC computer with a PDP-8 in one cabinet, thus being able to run programs written for either of the two architectures....
: A hybrid of the LINC

LINC

The LINC was a 12-bit, 2048-word computer. The LINC can be considered the first minicomputer and a foreruner to the personal computer.The LINC and other "MIT Group" machines were designed at Massachusetts Institute of Technology and eventually built by Digital Equipment Corporation ....
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

PDP-10

The PDP-10 was a mainframe computer manufactured by Digital Equipment Corporation from the late 1960s on; the name stands for "Programmed Data Processor model 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

PDP-11

16-bit

16-bit architectureThe HP 2100#Descendants and variants , introduced in 1975, was the world's first 16-bit microprocessor.Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816....
machine and another commercial success for DEC. (Also the LSI-11, primarily for embedded system

Embedded system

An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints....
s). The 32-bit

32-bit

The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295 or -2,147,483,648 through 2,147,483,647 using two's complement encoding....
VAX

VAX

VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs....
series was descended from it, and early VAX models had a PDP-11 compatibility mode. The 16-bit PDP-11 instruction set has been very influential, with processors ranging from the Motorola 68000

Motorola 68000

The Motorola 68000 is a 16/32-bit Complex instruction set computer microprocessor core designed and marketed by Freescale Semiconductor ....
to the Renesas H8 and Texas Instruments

Texas Instruments

Texas Instruments , better known in the electronics industry as TI, is an United States company based in Dallas, Texas, Texas, United States, renowned for developing and commercializing semiconductor and computer technology....
MSP430, inspired by its highly orthogonal, general-register oriented instruction set

Instruction set

An instruction set is a list of all the instruction , and all their variations, that a processor can execute.Instructions include:* Arithmetic such as add and subtract...
and rich addressing modes

Addressing mode

Addressing modes are an aspect of the instruction set architecture in most central processing unit designs. The various addressing modes that are defined in a given instruction set architecture define how Machine code Instruction in that architecture identify the operand of each instruction....
. The PDP-11 family was extremely long-lived, spanning 20 years and many different implementations and technologies. PDP-12: Descendant of the LINC-8. See LINC

LINC

The LINC was a 12-bit, 2048-word computer. The LINC can be considered the first minicomputer and a foreruner to the personal computer.The LINC and other "MIT Group" machines were designed at Massachusetts Institute of Technology and eventually built by Digital Equipment Corporation ....
and . PDP-13: Designation was not used, apparently due to superstition. PDP-14: A 1-bit machine intended as an industrial controller (PLC

Programmable logic controller

A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, control of amusement rides, or control of lighting fixtures....
). 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. It was their only 18-bit machine constructed from TTL

Transistor-transistor logic

File:68k ttl.jpgTransistor?transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor?transistor logic because both the logic gating function and the amplifying function are performed by transistors ....
integrated circuit

Integrated circuit

In electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin Wafer of semiconductor material....
s 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
TX-0

The TX-0, for Transistorized Experimental computer zero but affectionately referred to as tixo , was an early fully transistorized computer and contained a then-huge 64kilo of 18-bit words of core memory....
designed by MIT
Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private university research university located in Cambridge, Massachusetts, Massachusetts, United States....
's Lincoln Laboratory
Lincoln Laboratory

MIT Lincoln Laboratory, also known as Lincoln Lab, is a federally funded research and development center managed by the Massachusetts Institute of Technology and primarily funded by the United States Department of Defense....
, important as influence for DEC products including Ben Gurley's design for the PDP-1
LINC
LINC

The LINC was a 12-bit, 2048-word computer. The LINC can be considered the first minicomputer and a foreruner to the personal computer.The LINC and other "MIT Group" machines were designed at Massachusetts Institute of Technology and eventually built by Digital Equipment Corporation ....
(Laboratory Instrument Computer), originally designed by MIT
Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private university research university located in Cambridge, Massachusetts, Massachusetts, United States....
's Lincoln Laboratory
Lincoln Laboratory

MIT Lincoln Laboratory, also known as Lincoln Lab, is a federally funded research and development center managed by the Massachusetts Institute of Technology and primarily funded by the United States Department of Defense....
, 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 minicomputer
Minicomputer

A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems ....
s, and perhaps the first personal computer
Personal computer

A personal computer is any general-purpose computer whose original sales price, size, and capabilities make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator....
s 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
PDP-10

The PDP-10 was a mainframe computer manufactured by Digital Equipment Corporation from the late 1960s on; the name stands for "Programmed Data Processor model 10"....
running TOPS-20
TOPS-20

The TOPS-20 operating system by Digital Equipment Corporation was the second proprietary OS for the PDP-10 mainframe computer. TOPS-20 began in 1969 as Bolt, Beranek and Newman's TENEX operating system, using special paging hardware....
(officially known as a DECSYSTEM-20
DECSYSTEM-20

The DECSYSTEM-20 was a 36-bit Digital Equipment Corporation PDP-10 mainframe computer running the TOPS-20 operating system.PDP-10 computers running the TOPS-10 operating system were labeled DECsystem-10 as a way of differentiating them from the PDP-11....
).
SM EVM
SM EVM

SM EVM was general name for several types of Soviet Union minicomputers in 1970s and 1980s.Production started in 1975.Most types of SM EVM have been clone s of Digital Equipment Corporation PDP-11 and VAX....
series of computers in the USSR
DVK
DVK

DVK is a Russian clone of Programmed Data Processor minicomputer.The design is also known as Elektronika MS-0501 and Elektronika MS-0502.Earlier models of DVK series were based on K1801BM1 or K1801BM2 microprocessors with 16 bit address bus....
personal computers series are PDP clones developed in USSR in 70s.
Elektronika BK
Elektronika BK

Elektronika BK was a series of 16-bit PDP-11-compatible Soviet Union home computers developed by NPO Scientific Center, at that time the leading Soviet microcomputer design team, responsible also for more powerful UKNC and DVK micros....
UKNC
UKNC

UKNC was a Soviet Union PDP-11-compatible educational computer, aimed at teaching school informatics course. It is also known as Elektronika MS-0511....

External links

, still runnable in a German computer museum
Gordon Bell interview at the Smithsonian
on Gordon Bell's site at Microsoft.
shows a recently restored PDP-12
information about the PDP-7 and PDP7A including some manuals and a customer list covering 99 of the 120 systems shipped.

Various sites list documents by Charles Lasner, the creator of the alt.sys.pdp8 discussion group, and related documents by various members of the alt.sys.pdp8 readership with even more authoritative information about the various models, especially detailed focus upon the various members of the PDP-8 "family" of computers both made and not made by DEC.