ICL Distributed Array Processor - Revision history

imported>PaulBoddie: /* After ICL */ Added CPP, Gamma reference.

2025-12-02T23:29:43Z

After ICL: Added CPP, Gamma reference.

← Previous revision		Revision as of 23:29, 2 December 2025
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	==After ICL==		==After ICL==
	The DAP [IP] was sold off to a [[venture capital]]-funded [[start-up]] company [[Active Memory Technology]]		The DAP [IP] was sold off to a [[venture capital]]-funded [[start-up]] company [[Active Memory Technology]]
	(AMT) which was then taken over by [[Cambridge Parallel Processors]] (CPP).		(AMT) which was then taken over by [[Cambridge Parallel Processors]] (CPP). It was enhanced and made smaller and faster as the Gamma series.<ref name="unigramx19941114_amt">{{ cite news \| url=https://archive.org/details/UnigramX1994468-518/page/n330/mode/1up \| title=Cambridge Parallel to Debut Gamma MPP Box \| work=Unigram/X \| date=14 November 1994 \| access-date=3 December 2025 \| pages=7 }}</ref> An 8-bit processor with some local 8-bit wide memory was added to the processor and fast IO capabilities were implemented. It could be programmed in either [[C++]] or [[Fortran-Plus]]. These were more flexible than DAP FORTRAN, in particular they automatically took care of choosing a mapping from user specified matrix and vector bounds to the underlying hardware.
	It was enhanced and made smaller and faster as the Gamma series.
	An 8-bit processor with some local 8-bit wide memory was added to the
	processor and fast IO capabilities were implemented. It could be programmed in either [[C++]] or [[Fortran-Plus]]. These were more flexible than DAP FORTRAN, in particular they automatically took care of choosing a mapping from user specified matrix and vector bounds to the underlying hardware.

	Sample DAPs are in storage at the [[Computer History Museum]].		Sample DAPs are in storage at the [[Computer History Museum]].
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	==Mini-DAP and Mil-DAP==		==Mini-DAP and Mil-DAP==
	~~Between~~ 1984 and 1987~~, ICL developed a scaled-down version of the original DAP featuring a 32×32 array of processing elements~~. The commercial ~~iteration~~ was ~~marketed as~~ the '''Mini-DAP''' ~~and was typically interfaced~~ to ~~the~~ [[PERQ]] ~~workstation~~, ~~earning it~~ the ~~alternative name~~ '''~~PERQ~~-DAP'''.<ref ~~name="dap-brochure"~~>{{cite ~~web~~ \|url=~~https~~://www.~~chilton-computing~~.~~org~~.uk/~~inf/literature~~/~~brochures~~/~~p007~~.htm \|title=DAP ~~510 Brochures~~ \|~~publisher~~=~~Chilton Computing / UKRI Science and Technology Facilities Council~~ \|~~access-~~date=~~25 June 2025~~}}</ref>		{{Expand section\|date=June 2008}}
			A smaller 32x32 version was created between 1984 and 1987. The commercial version was called the '''Mini-DAP''', normally attached to a [[PERQ]] system (so was sometimes called the PERQ-DAP), and the ruggedised military version was called the '''Mil-DAP'''.<ref>{{cite journal \|url=http://www.cs.man.ac.uk/CCS/res/res25.htm#h \|title=Mil-DAP Resurrection Project \|author=Brian Russell \|journal=Computer Resurrection \|issue=5 \|date=Summer 2001}}</ref><ref name="sciencemuseum-2004-246">{{ cite web \| url=https://collection.sciencemuseumgroup.org.uk/objects/co520977/parallel-processor-computer \| title=Parallel Processor Computer \| website=Science Museum Group Collection \| access-date=21 October 2025 }}</ref>
	ICL's Research Applications Laboratory (RAL) recognized the Mini-DAP as a "very fast add-on parallel processor to the ICL PERQ", particularly effective for image-processing workloads where the DAP’s memory could serve as a bitmap frame buffer.<ref name="~~dap~~-~~brochure" /> Initial prototype work began around mid-1983, with delivery to RAL delayed from early 1985 due to interface development challenges.<ref name="dap~~-~~brochure~~" />

	A military-grade version, dubbed the '''Mil-DAP''', was also created. This ruggedized variant was designed to withstand field deployment and environmental extremes. One surviving specimen, serial number M002/005, is identified as an early example of parallel processor computers in military use.<ref>{{cite web \|url=https://collection.sciencemuseumgroup.org.uk/objects/co520977/parallel-processor-computer \|title=Parallel Processor Computer ~~– Mil-DAP~~ \|~~publisher~~=Science Museum Group Collection \|access-date=25 June 2025}}</ref><ref>{{cite web \|url=https://www.gettyimages.ae/detail/news-photo/small-military-version-of-of-the-icl-distributed-array-news-photo/90758793 \|title=MIL-DAP parallel processor computer, c.1979 \|publisher=Getty Images \|access-date=25 June 2025}}</ref>

	==See also==		==See also==

imported>BossyPirate: Expanded the "Mini-DAP and Mil-DAP" section with historical and technical details; added reliable sources.

2025-06-25T13:22:44Z

Expanded the "Mini-DAP and Mil-DAP" section with historical and technical details; added reliable sources.

← Previous revision		Revision as of 13:22, 25 June 2025
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	==Mini-DAP and Mil-DAP==		==Mini-DAP and Mil-DAP==
	~~{{Expand section\|date=June 2008}}~~		Between 1984 and 1987, ICL developed a scaled-down version of the original DAP featuring a 32×32 array of processing elements. The commercial iteration was marketed as the '''Mini-DAP''' and was typically interfaced to the [[PERQ]] workstation, earning it the alternative name '''PERQ-DAP'''.<ref name="dap-brochure">{{cite web \|url=https://www.chilton-computing.org.uk/inf/literature/brochures/p007.htm \|title=DAP 510 Brochures \|publisher=Chilton Computing / UKRI Science and Technology Facilities Council \|access-date=25 June 2025}}</ref>
	~~A smaller 32x32 version was created between~~ 1984 and 1987. The commercial ~~version~~ was ~~called~~ the '''Mini-DAP'''~~, normally attached~~ to a [[PERQ]] ~~system (so was sometimes called~~ the PERQ-DAP), ~~and~~ the ~~ruggedised~~ military version ~~was called~~ the '''Mil-DAP'''.<ref>{{cite ~~journal~~ \|url=~~http~~://~~www.cs~~.~~man~~.ac.uk/~~CCS~~/~~res~~/~~res25.htm#h~~ \|title=Mil-DAP ~~Resurrection Project~~ \|~~author~~=~~Brian Russell~~ \|~~journal~~=~~Computer Resurrection~~ \|~~issue~~=5 \|date=~~Summer 2001~~}}</ref>
			ICL's Research Applications Laboratory (RAL) recognized the Mini-DAP as a "very fast add-on parallel processor to the ICL PERQ", particularly effective for image-processing workloads where the DAP’s memory could serve as a bitmap frame buffer.<ref name="dap-brochure" /> Initial prototype work began around mid-1983, with delivery to RAL delayed from early 1985 due to interface development challenges.<ref name="dap-brochure" />

			A military-grade version, dubbed the '''Mil-DAP''', was also created. This ruggedized variant was designed to withstand field deployment and environmental extremes. One surviving specimen, serial number M002/005, is identified as an early example of parallel processor computers in military use.<ref>{{cite web \|url=https://collection.sciencemuseumgroup.org.uk/objects/co520977/parallel-processor-computer \|title=Parallel Processor Computer – Mil-DAP \|publisher=Science Museum Group Collection \|access-date=25 June 2025}}</ref><ref>{{cite web \|url=https://www.gettyimages.ae/detail/news-photo/small-military-version-of-of-the-icl-distributed-array-news-photo/90758793 \|title=MIL-DAP parallel processor computer, c.1979 \|publisher=Getty Images \|access-date=25 June 2025}}</ref>

	==See also==		==See also==

imported>Headbomb: Add: journal, title. | Use this tool. Report bugs. | #UCB_Gadget

2025-06-06T13:44:03Z

Add: journal, title. | Use this tool. Report bugs. | #UCB_Gadget

New page

{{Use dmy dates|date=April 2022}}
The '''Distributed Array Processor''' ('''DAP''') produced by
[[International Computers Limited]] (ICL) was the world's first commercial
[[massively parallel computer]]. The original paper study was
complete in 1972 and building of the prototype began in 1974.
The first machine was delivered to
[[Queen Mary, University of London|Queen Mary College]] in 1979.<ref>{{cite journal |url=http://www.cs.man.ac.uk/CCS/res/res12.htm#f |title=From Torsional Mode Delay Lines to DAP |author=Gordon G Scarrott |journal=Computer Resurrection |issue=12 |date=Summer 1995}}</ref>

==Development==
The initial Pilot DAP was designed and implemented by Dr Stewart F Reddaway with the aid of David J Hunt and Peter M Flanders at the ICL Stevenage Labs.{{citation needed | date=July 2024}} Their manager and a major contributor was [[John Iliffe (computer designer)|John K Iliffe]], designer of the Basic Language Machine and known for [[Iliffe vector]]s.<ref>{{cite journal |url=http://www.cs.man.ac.uk/CCS/res/res33.htm#g |title=Letter to the editor |author=Stewart Reddaway |journal=Computer Resurrection |issue=33 |date=Spring 2004|volume=48 |pages=149–150 |doi=10.1016/j.lungcan.2004.09.011 |pmid=15777984 |url-access=subscription }}</ref> The pilot implementation had a 32×32 processing element arrangement.<ref name="newscientist19760617_dap">{{ cite magazine | url=https://archive.org/details/bub_gb_m8S4bXj3dcMC/page/n11/mode/2up | title=Computers by the thousand | magazine=New Scientist | last1=Parkinson | first1=Dennis | date=17 June 1976 | access-date=7 July 2024 | pages=626–627 }}</ref>

The ICL DAP had 64×64 single bit [[processing element]]s (PEs) with 4096 bits of storage per PE. It was attached to an [[ICL mainframe]] and its memory was mapped into the mainframe's memory. Programs for the DAP were written in [[DAP FORTRAN]] which was [[FORTRAN]] extended with 64×64 matrix and 64 element vector primitives. DAP Fortran compiled to an [[assembly language]] called APAL (Array Processor Assembly Language). The DAP had a [[single instruction, multiple data]] (SIMD) architecture. Each operation could be performed under the control of a mask which controlled which elements were affected. Array programs were executed as [[subroutines]] of normal mainframe FORTRAN programs and IO was handled by the mainframe.

Operationally, there was an overhead to transfer computational data into and out of the array, and problems which did not fit the 64×64 matrix imposed additional complexity to handle the boundaries (65×65 was perhaps the worst case!)—but for problems which suited the architecture, it could outperform the current [[Cray]] pipeline architectures by two orders of magnitude. The [[ICL 2900 Series|ICL 2980]] was not a popular machine and this held back the use of the DAP as an attached processor was restricted initially to this one range.

The design as described in Reddaway's 1973 paper is pretty much that which was implemented in the first commercial version except the facility to supply address bits from the processing elements was removed. This change greatly simplified hardware error detection. A notable extra facility was carry propagation to simplify vector mode addition.<ref>{{cite journal |url=http://aggregate.org/EE686/SIMD/p61-reddaway.pdf |author=S. F. Reddaway |title=DAP—a distributed array processor |journal=ACM SIGARCH Computer Architecture News |pages=61–65 |publisher=ACM Press |year=1973|volume=2 |issue=4 |doi=10.1145/633642.803971 }}</ref>

==After ICL==
The DAP [IP] was sold off to a [[venture capital]]-funded [[start-up]] company [[Active Memory Technology]]
(AMT) which was then taken over by [[Cambridge Parallel Processors]] (CPP).
It was enhanced and made smaller and faster as the Gamma series.
An 8-bit processor with some local 8-bit wide memory was added to the
processor and fast IO capabilities were implemented. It could be programmed in either [[C++]] or [[Fortran-Plus]]. These were more flexible than DAP FORTRAN, in particular they automatically took care of choosing a mapping from user specified matrix and vector bounds to the underlying hardware.

Sample DAPs are in storage at the [[Computer History Museum]].

CPP ceased trading in 2004.

==Mini-DAP and Mil-DAP==
{{Expand section|date=June 2008}}
A smaller 32x32 version was created between 1984 and 1987. The commercial version was called the '''Mini-DAP''', normally attached to a [[PERQ]] system (so was sometimes called the PERQ-DAP), and the ruggedised military version was called the '''Mil-DAP'''.<ref>{{cite journal |url=http://www.cs.man.ac.uk/CCS/res/res25.htm#h |title=Mil-DAP Resurrection Project |author=Brian Russell |journal=Computer Resurrection |issue=5 |date=Summer 2001}}</ref>

==See also==
* [[Connection Machine]]
* [[Goodyear MPP]]
* [[MasPar]]
* [[Parsytec]]
* [[SUPRENUM]]

==References==
<references />

==External links==
* {{cite book |title=Massively parallel computing with the DAP |author1=Dennis Parkinson |author2=John Litt |publisher=Pitman |year=1990 |series=Research monographs in parallel and distributed computing |isbn=978-0-273-08809-7}}
* [http://www.fano.co.uk/history/DAP.html DAP personal history]
* [http://www.chilton-computing.org.uk/acd/sus/perq_history/part_5/c25.htm PERQ-DAP]

{{ICL hardware|Distributed Array Processor}}

{{DEFAULTSORT:Icl Distributed Array Processor}}
[[Category:ICL mainframe computers|DAP]]
[[Category:Massively parallel computers]]
[[Category:SIMD computing| ]]
[[Category:International Computers Limited|DAP]]