Design, hardware, and operating software of a special purpose computer built for the Monte Carlo simulations of a wide class of random Ising spin systems is described. The machine is quite versatile, easy to operate, and executes programs written in a high level C language. It is a 32‐bit bus oriented system, with a very fast, dedicated Monte Carlo processor and a general purpose single‐board computer sharing the 16‐Mbyte address space. The former processor executes the basic Monte Carlo heat bath algorithm, and the latter performs required physical ‘‘measurements’’ on spin configurations and handles communication with a UNIX host machine. The host computer is used to compile and download programs and to receive small quantities of reduced data for permanent storage and further analysis.