Ultracomputer
Encyclopedia
The NYU
New York University
New York University is a private, nonsectarian research university based in New York City. NYU's main campus is situated in the Greenwich Village section of Manhattan...

 Ultracomputer is a significant processor design in the history of parallel computing
Parallel computing
Parallel computing is a form of computation in which many calculations are carried out simultaneously, operating on the principle that large problems can often be divided into smaller ones, which are then solved concurrently . There are several different forms of parallel computing: bit-level,...

. The system has N processors, N memories and an N log N message-passing switch
Switch
In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....

 connecting them. The switch uses an innovative fetch-and-add
Fetch-and-add
In computer science, the fetch-and-add CPU instruction is a special instruction that atomically modifies the contents of a memory location. It is used to implement mutual exclusion and concurrent algorithms in multiprocessor systems, a generalization of semaphores.In uniprocessor systems, it is...

 instruction which will combine references from several processors into a single reference, to reduce memory contention.

The machine was developed in the 1980s
1980s
File:1980s decade montage.png|thumb|400px|From left, clockwise: The first Space Shuttle, Columbia, lifted off in 1981; American President Ronald Reagan and Soviet leader Mikhail Gorbachev eased tensions between the two superpowers, leading to the end of the Cold War; The Fall of the Berlin Wall in...

 at the Courant Institute of Mathematical Sciences
Courant Institute of Mathematical Sciences
The Courant Institute of Mathematical Sciences is an independent division of New York University under the Faculty of Arts & Science that serves as a center for research and advanced training in computer science and mathematics...

 Computer Science Department, based on a concept developed by Jacob T. Schwartz. Most of the work done was theoretical, but two prototypes were built:
  • An 8 processor bus-based machine
  • A 16 processor, 16 memory-module machine with custom VLSI switches supporting the fetch-and-add instruction.
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