A logic package of NEAC Series 2200 Model 500

In October 1966, NEC completed the NEAC Series 2200 Model 500, a large computer which was the first Japanese produced machine to use monolithic integrated circuits (ICs) throughout the system. CTL (Complementary Transistor Logic) was used for the ICs, thus reducing the size of the system to one third to one sixth the size of equipment using discrete components, and improving reliability by more than 10 times.

Model 400 and lower models of NEAC series 2200 were developed under a license agreement with a U.S. company,　Honeywell. However, Model 500 was developed completely in-house and had many enhanced features in addition to those of other models to make it suitable for the central processing unit of a large-scale IDP (Information Data Processing) and real time system.

In the Model 400 and lower, the main memory unit was accessed character by character, but with the Model 500, 8 characters could be accessed simultaneously with a 1.5-microseconds cycle time, and this improved the effective memory cycle time from the viewpoint of the logic unit. Instruction look-ahead control, simultaneous operation of computation and input/output operation, and enhanced program-interruption capability were incorporated. Maximum memory capacity was 524,288 characters, and floating point division speed was 18.0 microseconds.