View source for PDP-7

{{Short description|Minicomputer introduced in 1964}}
{{Use mdy dates|date=November 2020}}
{{Infobox computing device
| name         = PDP-7
| title        =
| aka          =
| logo         =PDP-7 wordmark.svg
| image        = pdp7-oslo-2005.jpeg
| caption      = A modified PDP-7 under restoration in [[Oslo, Norway]]
| developer    =
| manufacturer = [[Digital Equipment Corporation]]
| family       = [[Programmed Data Processor]]
| type         = [[Minicomputer]]
| generation   =
| releasedate  = {{Start date and age|1965}}
| lifespan     =
| price        = {{USD|72000|1965}}
| discontinued =
| unitssold    = 120<ref name=liinfopdp7>{{cite web |url=http://www.linfo.org/pdp-7.html |title=PDP-7 Definition |date=September 27, 2007 |work=The Linux Information Project}}</ref><ref name=microsoftpdp7>{{cite web |url=https://research.microsoft.com/~gbell/Digital/timeline/1964-3.htm |title=1964 — PDP-7 |work=DIGITAL Computing Timeline |via=Microsoft |quote=Ultimately, 120 PDP-7s were produced and sold.}}</ref>
| unitsshipped = 120<ref name=microsoftpdp7 />
| media        =
| os           = DECsys, [[Unix]] (as "Unics")
| power        =
| soc          =
| cpu          =
| memory       = {{nowrap|4K words}} {{nowrap|(9.2 KB)}} (expandable up to {{nowrap|64K words}} {{nowrap|(144 KB).}})<ref name=liinfopdp7 />
| storage      = Paper-tape and dual transport [[DECtape]] drives (type 555)
| memory card  =
| display      = Printer
| graphics     =
| sound        =
| input        = Keyboard
| controllers  =
| camera       =
| touchpad     =
| connectivity =
| platform     = DEC 18-bit
| service      =
| dimensions   =
| weight       =
| topgame      =
| compatibility= [[PDP-1]]
| predecessor  = [[PDP-4]]
| successor    = [[PDP-9]]
| related      =
| website      = <!--{{URL|example.org}}-->
}}
[[File:Pdp-7-oslo-2004.jpeg|thumb|300px|right|Modified PDP-7 under restoration in Oslo, Norway]]
[[File:DEC PDP-7.jpg|thumb|200x200px|PDP-7 at living computer museum]]

The '''PDP-7''' is an [[18-bit computing|18-bit]] [[minicomputer]] produced by [[Digital Equipment Corporation]] as part of the [[Programmed Data Processor|PDP]] series. Introduced in 1964,<ref name=SOEM_DEC57.PRES/>{{rp|p.8}}<ref>{{cite journal|title=across the editor's desk: COMPUTING AND DATA PROCESSING NEWSLETTER - PDP-7 ANNOUNCED BY DIGITAL|journal=Computers and Automation|date=July 1964|volume=XIII|issue=7|page=45|url=http://www.bitsavers.org/magazines/Computers_And_Automation/196407.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bitsavers.org/magazines/Computers_And_Automation/196407.pdf |archive-date=2022-10-09 |url-status=live|access-date=2020-09-05}}</ref> shipped since 1965, it was the first<ref name=SOEM>{{cite web
|url=https://www.soemtron.org/pdp7.html |title=Digital Equipment Corporation PDP-7 |website=soemtron.org
|date=2009 |author=Tore Sinding Bekkedal}}</ref> to use their [[Flip-Chip module|Flip-Chip]] technology. With a cost of {{USD|72,000}}, it was cheap but powerful by the standards of the time. The PDP-7 is the third of Digital's 18-bit machines, with essentially the same [[instruction set architecture]] as the [[PDP-4]] and the [[PDP-9]].

==Hardware==
The PDP-7 was the first [[wire wrap|wire-wrapped]] PDP computer.  The computer has a memory cycle time of {{nowrap|1.75 µs}} and an add time of {{nowrap|4 µs}}. [[Input/output]] (I/O) includes a keyboard, printer, [[punched tape]] and dual transport [[DECtape]] drives (type 555).<ref>{{cite web |url=https://dictionary.reference.com/browse/PDP-7 |title=Pdp-7 |work=reference.com Computing Dictionary |archive-url=https://web.archive.org/web/20130616014501/http://dictionary.reference.com/browse/PDP-7 |archive-date=June 16, 2013}}</ref> The standard [[Magnetic-core memory|core memory]] capacity is {{nowrap|4K words}} {{nowrap|(9 KB)}} but expandable up to {{nowrap|64K words}} {{nowrap|(144 KB).}}<ref name=liinfopdp7 />

The PDP-7 weighs about {{convert|1100|lb|kg}}.<ref>{{cite web |title=PDP-7 documents |url=http://www.bitsavers.org/pdf/dec/pdp7/ |website=www.bitsavers.org|at=PDP-7_Maint.pdf, p. 1-14 (32)}}</ref>

==Software==
'''DECsys''', the first operating system for DEC's 18-bit computer family (and DEC's first operating system for a computer smaller than its 36-bit timesharing systems), was introduced in 1965. It provides an interactive, single user, program development environment for [[Fortran]] and [[assembly language]] programs.<ref name=DECsys>{{cite web |url=http://simh.trailing-edge.com/docs/decsys.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://simh.trailing-edge.com/docs/decsys.pdf |archive-date=2022-10-09 |url-status=live |title=Technical Notes on DECsys |first=Bob |last=Supnik |date=June 19, 2006}}</ref>

In 1969, [[Ken Thompson]] wrote the first [[Unix|UNIX]] system, then named Unics as a pun on [[Multics]] despite only using two design elements from Multics,<ref>{{cite conference |last=Ritchie |first=Dennis M. |author-link=Dennis Ritchie |year=1977 |title=The Unix Time-sharing System: A retrospective |conference=Tenth Hawaii International Conference on the System Sciences |url=https://www.bell-labs.com/usr/dmr/www/retro.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.bell-labs.com/usr/dmr/www/retro.pdf |archive-date=2022-10-09 |url-status=live |quote=a good case can be made that UNIX is in essence a modern implementation of MIT’s CTSS system}}</ref><ref>{{cite book |last=Seibel |first=Peter |date=2009 |title=Coders at work : reflections on the craft of programming |location=New York |publisher=Apress |page=463 |isbn=9781430219491 |quote=The things that I [Ken Thompson] liked [about Multics] enough to actually take were the hierarchical file system and the shell}}</ref> in assembly language on a PDP-7,<ref>{{cite web |first=Dennis M. |last=Ritchie |url=https://www.bell-labs.com/usr/dmr/www/chist.html |title=The Development of the C Language}}</ref> as the operating system for ''[[Space Travel (video game)|Space Travel]]'', a game which requires graphics to depict the motion of the planets. A PDP-7 was also the development system used during the development of [[MUMPS]] at [[Massachusetts General Hospital|MGH]] in [[Boston]] a few years earlier.

==Sales==
The PDP-7  was described as "highly successful."<ref name=RICM>{{cite web |url=https://www.ricomputermuseum.org/collections-gallery/equipment/dec-pdp-9
|website=Rhode Island Computer Museum |title=DEC PDP-9, System Number 319}}</ref> A combined total of 120 of the PDP-7 and PDP-7A were sold.<ref name=SOEM_DEC57.PRES>{{cite web
|url=https://www.soemtron.org/downloads/decinfo/decdigital1957tothepresent1978-102630349.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.soemtron.org/downloads/decinfo/decdigital1957tothepresent1978-102630349.pdf |archive-date=2022-10-09 |url-status=live
|title=Digital Equipment Corporation - 1957 to the present}}</ref>{{rp|p.8}} A [[Digital Equipment Corporation|DEC]] publication states that the first units shipped to customers in November 1964.

Eleven systems were shipped to the UK.<ref name=SOEM/>

==Restorations==
At least four PDP-7s were confirmed to still exist as of 2011<ref name=SOEM/> and a fifth was discovered in 2017.<ref name=Yerian/>

A PDP-7A (serial number 115) was under restoration in [[Oslo]], Norway;<ref>{{cite web|url=https://heim.ifi.uio.no/~toresbe/dec |title=Picture album of PDP-7 restoration project |access-date=June 24, 2005 |url-status=dead |archive-url=https://web.archive.org/web/20120715211948/https://heim.ifi.uio.no/~toresbe/dec/pdp7/agi/ |archive-date=July 15, 2012 }} PDP-7 restoration project located in Oslo, Norway.</ref> a second PDP-7A (serial number 113) previously located at the [[University of Oregon]] in its Nuclear Physics laboratory is now at the [[Living Computer Museum]] in Seattle, Washington and is completely restored to running condition after being disassembled for transport;<ref>{{cite web|url=https://www.cs.uoregon.edu/Activities/talks/20110113-Lefevre.php |title=Colloquium Details - The University's 40 year old PDP-7 computer is alive again in Seattle|access-date=March 2, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120314021733/http://www.cs.uoregon.edu/Activities/talks/20110113-Lefevre.php |archive-date=March 14, 2012 }} University of Oregon's PDP-7 moves to the Living Computer Museum in Seattle, Washington. Alternate host at https://www.soemtron.org/pdp7no113systeminfo.html "January 2011" section.</ref> Another PDP-7 (serial number 47) is known to be in the collection of Max Burnet near Sydney, Australia, a fourth PDP-7 (serial number 33) is in storage at the [[Computer History Museum]]  in Mountain View, California  and a fifth PDP-7 (serial number 129) belonging to Fred Yerian is also located at the Museum, and has been demonstrated running Unix version 0 and compiling a [[B (programming language)|B program]].<ref name=Yerian>{{cite web|url=https://livingcomputers.org/Blog/Restoring-UNIX-v0-on-a-PDP-7-A-look-behind-the-sce.aspx |title=Restoring UNIX v0 on a PDP-7: A look behind the scenes|access-date=November 18, 2019 }}</ref>

==References==
{{Reflist}}

==External links==
* [https://www.soemtron.org/pdp7.html Information about the PDP-7 and PDP-7/A], including some manuals and a customer list covering 99 of the systems shipped, Digital Equipment Corporation PDP-7.
* {{webarchive |url=https://web.archive.org/web/20140402194704/http://www.bell-labs.com/history/unix/pdp7.html |date=April 2, 2014 |title=''"The famous PDP-7 comes to the rescue"'' (Bell Labs' Unix history) }}

{{DEC hardware}}

[[Category:DEC minicomputers]]
[[Category:Transistorized computers]]
[[Category:18-bit computers]]
[[Category:Computer-related introductions in 1965]]
[[Category:Products introduced in 1965]]