The NYU Ultracomputer—Designing an MIMD Shared Memory Parallel Computer

Allan Gottlieb, Ralph Grishman, Kevin P. McAuliffe, Marc Snir, Clyde P. Kruskal

Research output: Contribution to journalArticlepeer-review


We present the design for the NYU Ultracomputer, a shared-memory MIMD parallel machine composed of thousands of autonomous processing elements. This machine uses an enhanced message switching network with the geometry of an Omega-network to approximate the ideal behavior of Schwartz's paracomputer model of computation and to implement efficiently the important fetch-and-add synchronization primitive. We outline the hardware that would be required to build a 4096 processor system using 1990's technology. We also discuss system software issues, and present analytic studies of the network performance. Finally, we include a sample of our effort to implement and simulate parallel variants of important scientific programs.

Original languageEnglish (US)
Pages (from-to)175-189
Number of pages15
JournalIEEE Transactions on Computers
Issue number2
StatePublished - Feb 1983


  • Computer architecture
  • MIMD
  • VLSI
  • fetch-and-add
  • multiprocessor
  • omega-network
  • parallel computer
  • parallel processing
  • shared memory
  • systolic queues

ASJC Scopus subject areas

  • Software
  • Theoretical Computer Science
  • Hardware and Architecture
  • Computational Theory and Mathematics


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