J–Machine

{{Short description|Parallel computer}}The '''J–Machine''' ('''Jellybean-Machine''') was a parallel computer designed by the MIT Concurrent VLSI Architecture group in conjunction with the Intel Corporation. The machine used "jellybean" parts—cheap and multitudinous commodity parts, each with a processor, memory, and a fast communication interface—and a novel network interface to implement fine grained parallel programs.<ref>{{Cite web | title = The J-Machine: A Retrospective | url = http://cva.stanford.edu/publications/1998/jm_retro.pdf | year = 1998 | first1 = William | last1 = Dally | authorlink = Bill Dally | first2 = Andrew | last2 = Chang | first3 = Andrew | last3 = Chien | first4 = Stuart | last4 = Fiske | first5 = Waldemar | last5 = Horwat | first6 = John | last6 = Keen | first7 = Richard | last7 = Lethin | first8 = Michael | last8 = Noakes | first9 = Peter | last9 = Nuth | accessdate = 2009-06-17 }}</ref>

== History ==

The J-machine project was started in 1988 based on work in Bill Dally's doctoral work at Caltech.<ref>{{Cite web |title=J-Machine Project Page |url=http://web.mit.edu/sctv/OldFiles/old_sites/20030413045411/http://cva.stanford.edu/j-machine/cva_j_machine.html |access-date=2022-12-30 |website=web.mit.edu}}</ref>

The philosophy of the work was "processors are cheap and memory is expensive," the ''J'' in the project's title standing for jellybean which are small cheap candies. In order to make use of large numbers of processors, the machine featured a novel network interface using message passing.<ref>{{cite book | title = Principles and practices of interconnection networks | url = https://archive.org/details/principlespracti00dall_883 | url-access = limited | first1 = William J. | last1 = Dally | authorlink = Bill Dally | first2 = Brian | last2 = Towles | publisher = Morgan Kaufmann | year = 2004 | isbn = 0-12-200751-4 | pages =[https://archive.org/details/principlespracti00dall_883/page/n67 102]–109 }}</ref> This allowed a node to send a message to any other node within 2 microseconds.<ref>{{cite book | title = Parallel supercomputing in MIMD architectures | chapter = 12. The J-Machine: A fine-grain concurrent computer | last = Hord | first = R. Michael | publisher = CRC Press | year = 1993 | isbn = 0-8493-4417-4 | pages = 225–236}}</ref>

Three 1024-node J-machine systems have been built and are kept at MIT, Caltech and Argonne National Laboratory.<ref>{{cite web | url = http://cva.stanford.edu/projects/j-machine/ | title = The Jellybean Machine | publisher = CVA Group, Stanford University | accessdate = 2009-06-17 }}</ref>

== External links == * [http://cva.stanford.edu/projects/j-machine/ The Jellybean Machine]

== Notes ==

{{DEFAULTSORT:J-Machine}} Category:Massively parallel computers