UWGSP4 (University of Washington Graphics System Processor) consists of four parts: a parallel vector processor, a shared-memory system, an interconnection network, and a graphics subsystem. The parallel vector processor was provided mainly for imaging and general-purpose computing, whereas the main functions of the graphics subsystem are to generate realistic three-dimensional images and to draw the display screen. Among the four parts, the shared memory and the interconnection network were designed to fully support the parallel vector processor and graphics subsystem so as to yield high sustained performance. A discussion is presented of the architecture of UWGSP4, simulated performance figures for several imaging and graphics algorithms, and applications areas. >