NEC ACOS System 250

This was a small general-purpose computer, whose CPU was comprised of main memory and 5 distributed processors (an arithmetic processor, system control processor, service processor, magnetic disk processor and communications control processor). It employed N-channel MOS LSI with 3,300 gates for LSI logic, and 64K MOS RAM for memory, thereby reducing size, weight and floor space, and enabling use of commercial power sources. It had enhanced RAS design, and at the same time was capable of automatic operation. The main memory capacity was a maximum of 2 megabytes, and cycle time was 580 nanoseconds per 4 bytes. Due to the use of LSI throughout, the S250 had a cost-performance ratio far better than IBM machines, and which made the S250 a best-seller, selling a total of 2,146 machines.