OKITAC 5090C

The OKITAC 5090 "A Model" was first completed in 1961, but its predecessor (the OKITAC 5080) was developed as a prototype in the previous year. The results gained by developing the OKITAC 5080 were reflected in the OKITAC 5090 and six models were eventually produced as a series until 1963. While almost all other Japanese models at that time used magnetic drums, these models were transistor-based computers that used magnetic core memory for their main memory unit and employed a static circuit system.

The OKITAC 5090 was a best-seller primarily at universities, which were a big market at that time. The reasons usually given for this are its high-speed processing by use of magnetic cores, its efficiency in connecting high-speed input/output devices without needing to use buffer memory at input/output interfaces, its wealth of numerous input/output devices in general, and above all, the fact that it was connected to a high-speed line printer. The application of magnetic core memory is most notably attributed to the research results of Professor Toru Motooka at Tokyo University.

The particular computer system being considered for certification is an OKITAC 5090 "C Model", which had a main memory of 4,096 words (numeric words were decimal, 12 digits/word and instruction words were the pair-order type with 2 instructions/word) with a calculation speed of 0.4 milliseconds for fixed-point arithmetic calculation and 0.7–1.4 milliseconds for floating point arithmetic calculation. The system was equipped various input/output devices, such as an electric typewriter, a photoelectric paper tape reader, a high-speed line printer, and a magnetic tape drive.

This very computer system was used in actual lessons taught at the Senshu University School of Business Administration (established in 1962) and later kept in a warehouse for many years after completing its primary use. However, in 2001, it was put on display in front of the present-day Senshu University Information Technology Center's front desk.