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. Their manager and a major contributor was John K Iliffe[2] who had designed the Basic Language Machine—he is well known nowadays for Iliffe vectors.
The ICL DAP had 64×64 single bit processing elements (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 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.[3]
After ICLedit
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.
This section needs expansion. You can help by adding to it. (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.[4]
^Gordon G Scarrott (Summer 1995). "From Torsional Mode Delay Lines to DAP". Computer Resurrection (12).
^Stewart Reddaway (Spring 2004). "Letter to the editor". Computer Resurrection. 48 (33): 149–150. doi:10.1016/j.lungcan.2004.09.011. PMID 15777984.
^S. F. Reddaway (1973). "DAP - a distributed array processor" (PDF). Proceedings of the 1st Annual Symposium on Computer Architecture, (Gainesville, Florida). ACM Press. 2 (4): 61–65. doi:10.1145/633642.803971.
^Brian Russell (Summer 2001). "Mil-DAP Resurrection Project". Computer Resurrection (5).
External linksedit
Dennis Parkinson; John Litt (1990). Massively parallel computing with the DAP. Research monographs in parallel and distributed computing. Pitman. ISBN978-0-273-08809-7.
DAP personal history
PERQ-DAP
November 15, 2023
distributed, array, processor, distributed, array, processor, produced, international, computers, limited, world, first, commercial, massively, parallel, computer, original, paper, study, complete, 1972, building, prototype, began, 1974, first, machine, delive. 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 College in 1979 1 Contents 1 Development 2 After ICL 3 Mini DAP and Mil DAP 4 See also 5 References 6 External linksDevelopment editThe 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 Their manager and a major contributor was John K Iliffe 2 who had designed the Basic Language Machine he is well known nowadays for Iliffe vectors The ICL DAP had 64 64 single bit processing elements 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 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 3 After ICL editThe 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 editThis section needs expansion You can help by adding to it 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 4 See also editConnection Machine Goodyear MPP MasPar Parsytec SUPRENUMReferences edit Gordon G Scarrott Summer 1995 From Torsional Mode Delay Lines to DAP Computer Resurrection 12 Stewart Reddaway Spring 2004 Letter to the editor Computer Resurrection 48 33 149 150 doi 10 1016 j lungcan 2004 09 011 PMID 15777984 S F Reddaway 1973 DAP a distributed array processor PDF Proceedings of the 1st Annual Symposium on Computer Architecture Gainesville Florida ACM Press 2 4 61 65 doi 10 1145 633642 803971 Brian Russell Summer 2001 Mil DAP Resurrection Project Computer Resurrection 5 External links editDennis Parkinson John Litt 1990 Massively parallel computing with the DAP Research monographs in parallel and distributed computing Pitman ISBN 978 0 273 08809 7 DAP personal history PERQ DAP Retrieved from https en wikipedia org w index php title ICL Distributed Array Processor amp oldid 1162838452, wikipedia, wiki, book, books, library,
