Experience with pipelined multiple instruction streams

Pipelining has been used to implement efficient, high-speed vector computers. It is also an effective method for implementing multiprocessors. The Heterogeneous Element Processor (HEP) built by Denelcor Incorporated is the first commercially available computer system to use pipelining to implement multiple processes. This paper introduces the architecture and programming environment of the HEP and surveys a range of scientific applications programs for which parallel versions have been produced, tested, and analyzed on this computer. In all cases, the ideal of one instruction completion every pipeline step time is closely approached. Speed limitations in the parallel programs are more often a result of the extra code necessary to ensure synchronization than of actual synchronization lockout at execution time. The pipelined multiple instruction stream architecture is shown to cover a wide range of applications with good utilization of the parallel hardware.