Editing Programmed Data Processor

{{Short description|Name used for several lines of minicomputers}}
[[File:PDP-1.jpg|thumb|PDP-1]]
[[File:Dec pdp-6.lg.jpg|thumb|PDP-6]]
[[File:Pdp7-oslo-2005.jpeg|thumb|PDP-7]]
[[File:DEC PDP 8e.jpg|thumb|PDP-8/e]]
[[File:Pdp-11-40.jpg|thumb|PDP-11/40]]
[[File:PDP-12-Update-Uppsala.jpeg|thumb|PDP-12]]
[[File:PDP-15 at Varesezaal.jpg|thumb|PDP-15 (partial)]]
[[File:PDP-15 graphics terminal.agr.jpg|thumb|PDP-15 graphics terminal with [[light pen]] and [[Graphics tablet|digitizing tablet]] ]]

'''Programmed Data Processor''' ('''PDP'''), referred to by some customers, media and authors as "'''Programmable''' Data Processor,"<ref>{{cite web
|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19860004398.pdf
|title=VAS Demonstration  |website=nasa.gov|date=October 1985 |last1=Montgomery |first1=H. E. |last2=Uccellini |first2=L. W. }}</ref><ref>{{cite web
 |website     = harvard.edu
 |url         = http://www.innovation.seas.harvard.edu/files/Disruptive_technology.ppt
 |title       = New Market Disruption: The DEC Programmable Data Processor
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20170915114458/http://www.innovation.seas.harvard.edu/files/Disruptive_technology.ppt
 |archive-date = 2017-09-15
}}</ref><ref>{{cite book  |title=Computers in Analytical Chemistry
|page=153 |url=https://books.google.com/books?isbn=1483285626  |isbn=978-1483285627 |author=R Belcher   |date=2013}} 
"The term PDP is an acronym for Programmable Data Processor ... the series was introduced by their manufacturer, Digital Equipment Corporation ..."</ref> is a term used by the [[Digital Equipment Corporation]] from 1957 to 1990 for several lines of [[minicomputer]]s.<ref name=DEC_Hist>{{cite web
|url=https://digital.com/about/dec |title=The History of Digital Equipment Corporation}}</ref>

The name "PDP" intentionally avoids the use of the term "computer". At the time of the first PDPs, computers had a reputation of being large, complicated, and expensive machines. The [[venture capital]]ists behind Digital (especially [[Georges Doriot]]) would not support Digital's attempting to build a "computer" and the term "minicomputer" had not yet been coined.<ref>{{cite book|editor-last1=Henderson|editor-first1=Rebecca M.|editor-last2=Newell|editor-first2=Richard G.|title=Accelerating energy innovation : insights from multiple sectors|date=2011
|publisher=University of Chicago Press|location=Chicago|isbn=978-0226326832|page=180}}</ref><ref>{{cite book|last1=Huang
|first1=Han-Way|title=The atmel AVR microcontroller : MEGA and XMEGA in assembly and C|date=2014
|publisher=Delmar Cengage Learning|location=Australia ; United Kingdom|isbn=978-1133607298|page=4}}</ref> So instead, Digital used their existing line of logic modules to build a ''Programmed Data Processor'' and aimed it at a market that could not afford the larger computers.

The various PDP machines can generally be grouped into families based on [[word length]].

==Series==
Members of the PDP series include:<ref name=DEC57.PRES>{{cite book   
|title=DIGITAL EQUIPMENT CORPORATION - Nineteen Fifty-Seven To The Present
|url=http://s3data.computerhistory.org/pdp-1/dec.digital_1957_to_the_present_(1978).1957-1978.102630349.pdf
|date=1975 |publisher=Digital Equipment Corporation}}</ref>

;[[PDP-1]]: The original PDP, an [[18-bit computing|18-bit]] four-[[19-inch rack|rack]] machine used in early [[time-sharing]] [[operating system]] work, and prominent in MIT's early [[hacker culture]], which led to the (Massachusetts) [[Massachusetts Route 128#"America's Technology Highway"|Route 128 hardware startup belt]] (DEC's second home, [[Prime Computer]], etc.).  What is believed to be the first [[video game]], ''[[Spacewar!]]'', was developed for this machine, along with the first known [[word processing]] program for a general-purpose computer, "[[Expensive Typewriter]]".  It was based to some extent on the [[TX-0]] which [[Ben Gurley]] had also contributed to.  His engineering requirement was to build it from inventory (DEC's existing product, [[System Module]]s).

:The last of DEC's 53 PDP-1 computers was built in 1969, a decade<ref group="NB">the first was in December 1959, but often is referred to as "1960."</ref><ref name=DEC57.PRES/> after the first, and nearly all of them were still in use as of 1975.<ref name=DEC57.PRES/>{{rp|p.4}} "An average configuration cost $120,000" at a time "when most computer systems sold for a million dollars or more."

:Its architectural successors as 18-bit machines were the PDP-4, PDP-7, PDP-9, and the PDP-15.<ref name=EdT>{{cite web |url=http://ed-thelen.org/comp-hist/pdp-1.html  |title=PDP-1 |author=Ed Thelen}}</ref>

;PDP-2: A number reserved for an unbuilt, undesigned 24-bit design.
;PDP-3: First DEC-designed (for US "[[black budget]]" outfits) 36-bit machine, though DEC did not offer it as a product. The only PDP-3 was built from DEC modules by the [[CIA]]'s Scientific Engineering Institute (SEI) in [[Waltham, Massachusetts]] to process [[radar cross section]] data for the [[Lockheed A-12]] [[reconnaissance aircraft]] in 1960.<ref>{{cite web
|url=http://www.decconnection.org/announcements.htm
|title=Announcements from The DEC Connection
|date=2007-02-14
|access-date=2008-11-24
|work=The DEC Connection}}</ref><ref>{{cite web
|url=http://www.faqs.org/faqs/dec-faq/pdp8/
|title=PDP-8 Frequently Asked Questions
|date=2001-04-08
|access-date=2008-11-24
|work=www.faqs.org}}</ref>  Architecturally it was essentially a PDP-1 controlling a PDP-1 stretched to 36-bit word width.<ref>{{cite web|url=http://bitsavers.org/pdf/dec/pdp3/PDP-3_PrelimSpec.pdf|title=Preliminary Specification - Programmed Data Processor Model Three (PDP-3)|publisher=Digital Equipment Corporation|date=October 1960}}</ref><ref name=DEC57.PRES/>{{rp|p.4}}
;[[PDP-4]]: This 18-bit machine, first shipped in 1962<ref>{{cite book |title=Portraits in Silicon |page=[https://archive.org/details/portraitsinsilic00slat/page/210 210] |author=Robert Slater |date=1989 |isbn=978-0262691314 |url-access=registration |url=https://archive.org/details/portraitsinsilic00slat/page/210 }}</ref> of which "approximately 54 were sold" was a compromise: "with slower memory and different packaging" than the PDP-1, but priced at $65,000 - considerably less than its predecessor (about half the price).<ref name=DEC57.PRES/>{{rp|p.4}}  All later 18-bit PDP machines (7, 9 and 15) are based on a similar, but enlarged [[instruction set]], more powerful, but based on the same concepts as the 12-bit PDP-5/PDP-8 series. 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]]: It was the world's first commercially produced minicomputer<ref name=DEC57.PRES/>{{rp|p.4}} and DEC's first [[12-bit computing|12-bit]] machine (1963).  The instruction set was later expanded in the [[PDP-8]] to handle more bit rotations and to increase the maximum memory size from 4K words to 32K words. It was one of the first computer series with more than 1,000 built.{{clarify|reason=[[IBM 650]] from 1954 had ~2000 units; where did the claim that it was the first come from, I wonder?|date=January 2021}}
;[[PDP-6]]: This [[36-bit computing|36-bit]] machine, DEC's first large PDP computer, came in 1964 with the first DEC-supported [[timesharing]] system. 23 were installed.<ref name=DEC57.PRES/>{{rp|p.6}} Although the PDP-6 was "disappointing to management," it introduced the instruction set and was the prototype for the far more successful [[PDP-10]] and [[DECSYSTEM-20|DEC System-20]],<ref>{{cite book
|title=A History of Modern Computing  |page=[https://archive.org/details/historyofmodernc00ceru_0/page/209 209] |url=https://archive.org/details/historyofmodernc00ceru_0   |url-access=registration  |isbn=978-0262532037
|author=Paul E. Ceruzzi  |date=2012}}</ref><ref>{{cite book  |date=2014 
|title=Computer Engineering: A DEC View of Hardware Systems Design
|url=https://books.google.com/books?isbn=1483221105  |isbn=978-1483221106
|last1=Bell  |first1=C. Gordon   |last2=Mudge  |first2=J. Craig |last3=McNamara  |first3=John E. }}</ref> of which hundreds were sold.<ref>{{cite web |url=http://ed-thelen.org/comp-hist/pdp-6.html |title=PDP-6 |author=Ed Thelen   |website=Ed-Thelen.org}}</ref>
;[[PDP-7]]: Replacement for the PDP-4; DEC's first [[wire-wrap]]ped machine using the associated [[Flip-Chip module]] form-factor.  It was introduced in 1964,<ref name=EdT/> and a second version, the 7A, was subsequently added. A total of 120 PDP-7 and PDP-7A systems were sold.<ref name=DEC57.PRES/>{{rp|p.8}}

:The first version of [[Unix]], and the first version of [[B (programming language)|B]], a predecessor of [[C (programming language)|C]], were written for the PDP-7 at Bell Labs, as was the first version (by DEC) of [[MUMPS]].
;[[PDP-8]]: 12-bit machine (1965) with a tiny instruction set; DEC's first major commercial success and the start of the [[minicomputer]] revolution. Many were purchased (at discount prices, a DEC tradition, which also included free manuals for anyone who asked during the [[Ken Olsen]] years) by schools, university departments, and research laboratories.

:Over 50,000 units among various models of the family (A, E, F, I, S, L, M) were sold.<ref>{{cite web
|url=https://videogamehistorian.wordpress.com/tag/pdp-5
|title=PDP-5 Historical Interlude: From the Mainframe to the Minicomputer Part 3, DEC and Data General |date=11 December 2014 }}</ref> Later models are also used in the [[DECmate]] [[word processor]] and the [[VT-78]] [[workstation]]. 
;[[LINC-8]]: The system contained both a PDP-8 CPU and a [[LINC]] CPU; two instruction sets; 1966. Progenitor of the PDP-12.
;[[PDP-9]]: Successor to the PDP-7; DEC's first [[micro-program]]med machine (1966). It features a speed increase of approximately twice that of the PDP-7. The PDP-9 is also one of the first small or medium scale computers to have a keyboard monitor system based on DIGITAL's own small magnetic tape units ([[DECtape]]).<ref>{{cite web|title=PDP-9|url=https://archive.computerhistory.org/resources/text/DEC/dec.digital_(DEC)_timeline_1957-1997.102630354/1966-1.htm|work=Digital Computing Timeline|publisher=Computer History Museum|access-date=11 May 2020}}</ref>  The PDP-9 established [[minicomputer]]s as the leading edge of the computer industry.{{dubious|date=November 2018}}
;[[PDP-10]]: Also marketed as the DECsystem-10,<ref group="NB">whose CPU manual was named ''DECsystem-10/DECSYSTEM-20 Processor Reference Manual'' {{cite web|url=http://www.36bit.org/dec/manual/ad-h391a-t1.pdf|title=DECsystem-10/DECSYSTEM-20 Processor Reference Manual|publisher=DEC|access-date=14 November 2015|ref=referencemanual|url-status=dead|archive-url=https://web.archive.org/web/20151011152807/http://www.36bit.org/dec/manual/ad-h391a-t1.pdf|archive-date=11 October 2015}}</ref><ref group="NB">sometimes called a DEC-10</ref> this 36-bit timesharing machine (1966) was quite successful over several different implementations (KA, KI, KL, KS) and models.<ref group="NB">1055, 1090, 2020, 2040, 2065 and others</ref>  The instruction set is a slightly elaborated form of that of the PDP-6.

:The KL was also used for the [[DECSYSTEM-20]]. The KS was used for the 2020, DEC's entry in the [[Distributed computing|distributed processing]] market, introduced as "the world's lowest cost mainframe computer system."<ref>{{cite web |url=http://gordonbell.azurewebsites.net/digital/timeline/1978-2.htm |title=DECsystem-2020 - Gordon Bell}}</ref>
;[[PDP-11]]: The archetypal minicomputer (1970); a [[16-bit computing|16-bit]] machine and another commercial success for DEC. The [[LSI-11]] is a four-chip PDP-11 used primarily for [[embedded system]]s. The [[32-bit computing|32-bit]] [[VAX]] series is descended from the PDP-11, and early VAX models have a PDP-11 compatibility mode. 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 mode]]s. The PDP-11 family was extremely long-lived, spanning 20 years and many different implementations and technologies.
;[[PDP-12]]: 12-bit machine (1969), descendant of the LINC-8 and thus of the PDP-8.  It had one CPU that could change modes and execute the instruction set of either system.  See [[LINC]] and [http://users.rcn.com/crfriend/museum/doco/PDP-12/index.shtml PDP-12 User Manual]. With slight redesign, and different livery, officially followed by, and marketed as, the "Lab-8".<ref>examples of customer references to DEC-marketed LAB-8:<br>*A package of LAB 8/E subroutines for DEC OS/8 FORTRAN II - https://link.springer.com/article/10.3758/BF03202095 by U Arend - ?Sep 1, 1981 - Gonzalez, G.FORTRAN (Extended). An improved and extended version of the OS/8 FOR TRAN II compiler.
* DEC LAB-8/e (PDP-8/e) playing music - YouTube Video for DEC "lab-8" https://www.youtube.com/watch?v=akvSE5Z474c Apr 1, 2008 - Uploaded by Philipp Hachtmann This is a video of my 1971 DEC LAB-8/e minicomputer playing music.  In this video it is revealed where ...
* DEC LAB-8/e (PDP-8/e) CRT display running kaleidoscope - YouTube Video for DEC "lab-8" https://www.youtube.com/watch?v=tBaTzbsgQYk Mar 1, 2008 - Uploaded by Philipp Hachtmann. This is my LAB-8/e running the Kaleidoscope program on VC8-E (vector display controller) and VR14</ref>

;PDP-13: Designation was not used.
;[[PDP-14]]: A machine with 12-bit instructions, intended as an industrial controller ([[Programmable logic controller|PLC]]; 1969). It has no data memory or data registers; instructions can test Boolean input signals, set or clear Boolean output signals, jump conditional or unconditionally, or call a subroutine. Later versions (for example, the PDP-14/30) are based on PDP-8 physical packaging technology. I/O is line voltage.
;[[PDP-15]]: DEC's final 18-bit machine (1970).  It is the only 18-bit machine constructed from [[Transistor-transistor logic|TTL]] [[integrated circuit]]s rather than discrete transistors, and, like every DEC 18-bit system (except mandatory on the PDP-1, absent on the PDP-4) has an optional integrated [[vector graphics]] terminal, DEC's first improvement on its early-designed 34n where n equalled the PDP's number. Later versions of the PDP-15 run a real-time multi-user OS called "XVM". The final model, the PDP-15/76 uses a small PDP-11 to allow Unichannel peripherals to be used.<ref>{{cite book|title=Computer Engineering: A DEC View of Hardware Systems Design|first1=C. Gordon|last1=Bell|first2=J. Craig|last2=Mudge|first3=John E.|last3=McNamara|publisher=Digital Press|date=May 12, 2014|page=162|url=http://research.microsoft.com/en-us/um/people/gbell/Computer_Engineering/00000184.htm}}</ref>
;[[PDP-16]]: A "roll-your-own" digital system using [[Register-transfer level|Register Transfer Modules]],<ref>{{cite web
|url=https://www.researchgate.net/publication/306993084
|title=The Register Transfer Module Design Concept - ResearchGate}}</ref> mainly intended for industrial control systems with more capability than the PDP-14.  They could be used to design a custom controller consisting of a control structure and associated data storage and manipulation modules, or to design a small computer which could then be programmed.  The PDP-16 modules were based on the RTMs designed by Gordon Bell during his time at [[CMU]].  The PDP-16/M was introduced in 1972 as a pre-assembled set of the PDP-16 modules that could be programmed and was nicknamed a "Subminicomputer".

==Related computers==
* [[TX-0]] designed by [[Massachusetts Institute of Technology|MIT]]'s [[Lincoln Laboratory]], important as influence for DEC products including Ben Gurley's design for the PDP-1.  When the memory was replaced with a smaller one, the instruction set was expanded, and it was moved to the MIT campus.  When a PDP-1 arrived on campus, it was placed in the next room.  Software such as an assembler was ported from the TX-0 to the PDP-1 and the machines were connected for communications between them.
* [[LINC]] (Laboratory Instrument Computer), originally designed by [[Massachusetts Institute of Technology|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 [[minicomputer]]s, and perhaps the first [[personal computer]]s as well. The PDP-8 and PDP-11 are 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]]).
* Several [[PDP-11#Unlicensed clones|unlicensed clones of the PDP-11]].
* [[XKL#TOAD-1|TOAD-1]] and [[XKL#TOAD-2|TOAD-2]], [[Foonly]], and [[Systems Concepts]] PDP-10/DECSYSTEM-20-compatible machines.

==Notes==
{{Reflist|group="NB"}}

==References==
{{Reflist}}
* [[C. Gordon Bell]], [[J. Craig Mudge]], [[John E. McNamara]], [http://research.microsoft.com/%7EGBell/Computer%5FEngineering/ ''Computer 	Engineering: A DEC View of Hardware Systems Design''] (Digital, 1978)
* {{cite web|archive-url=https://web.archive.org/web/20060615180503/http://ed-thelen.org/comp-hist/TheCompMusRep/TCMR-V08.html |url=http://www.ed-thelen.org/comp-hist/TheCompMusRep/TCMR-V08.html |archive-date=2006-06-15|title=The Computer Museum Report, Volume 8: TX-0 alumni reunion, Spring 1984}}
* [[C. Gordon Bell|Bell]], C.G., [[John Grason|Grason]], J., and [[Allen Newell|Newell]], A., [http://research.microsoft.com/~gbell/designing_computers_and_digital_systems/index.html Designing Computers and Digital Systems]. Digital Press, Maynard, Mass., 1972.
* [[Conversations]] with David M. Razler (dmrazler@razler.net), owner/restorer of PDP-7s,8s,9s and 15s until the cost of hauling around 2 tons of DEC gear led him to sell off or give away everything he owned.

==External links==
{{Commons category|Programmed Data Processor}}
* [https://web.archive.org/web/20030807152602/http://www.village.org/pdp11/faq.pages/Crispin.html Mark Crispin's 1986 list of PDP's]
* [http://www.technikum29.de/en/computer/early-computers Several PDP and LAB's], still runnable in a German computer museum
* [https://web.archive.org/web/20050204001658/http://americanhistory.si.edu/csr/comphist/bell.htm#first%20commercial%20timesharing DEC's PDP-6 was the world's first commercial time-sharing system ] Gordon Bell interview at the Smithsonian
* [http://www.decodesystems.com/dec-product-timeline.html DEC PRODUCT TIMELINE]
* [http://research.microsoft.com/~gbell/CGB%20Files/Description%20and%20Use%20of%20RTM%20IEEE%207205%20c.pdf Description and Use of Register Transfer Modules] on Gordon Bell's site at Microsoft.
* [https://web.archive.org/web/20100709005751/http://pdp12.lofty.com/pdp12/index.html pdp12.lofty.com] shows a recently restored PDP-12
* http://www.soemtron.org/pdp7.html information about the PDP-7 and PDP7A including some manuals and a customer list covering 99 of the 120 systems shipped.
* {{gutenberg|no=29461|name=Preliminary Specifications: Programmed Data Processor Model Three}}

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.

{{DEC hardware}}
{{Authority control}}

[[Category:Minicomputers]]
[[Category:DEC hardware]]