The PACS name was derived from Processor Array for Continuum Simulation. Hoshino, Tsutomu who was at Kyoto University at the time, started studying a computer architecture based on a processor array, with the initial objective of simulating nuclear reactor cores. In 1980, PACS-32 (with a speed of 0.5 megaFLOPS) was completed. It was a parallel machine with 32 CPUs in an adjacently-linked two-dimensional torus array. PACS used an internal bus to directly couple CPUs, which ensured a wide bandwidth. During this time, Hoshino transferred to Tsukuba University, where he continued his PACS research.
PACS-128 was built at Tsukuba University after PACS-32, and later Mitsui Engineering & Shipbuilding produced the PAX-32J in a bid to commercialize the design.
The project continued to develop, resulting in the QCDPAX (Quantum Chromo Dynamics Processor Array Experiment) in 1990. A QCDPAX cabinet, parts, and related materials are stored at the National Museum of Nature and Science, Tokyo.
Compiled from p.194, "The History of Japanese Computers", edited by the Special Committee for the History of Computing, IPSJ. Ohmsha, 2010.