Kayashima Kozo was born on Nov. 10, 1932, and graduated from Electrical Engineering Course of Engineering Faculty of Kyoto University in March 1955. Immediately after his graduation, he joined Hitachi, and started his carrier of research engineer at its Central Research Laboratory. After studying statistics and operations research for about a year, he started developing an electronic computer with the use of parametron, under the leadership of Takada Shohei and Shimada Shozo. In December 1957, he completed the computer named HIPAC Mk-1, which consisted of about 3,000 parametrons as logic elements and a magnetic drum as a memory device. The magnetic drum stored 1,024 words of 38 bits each, and its average access time was about 5 ms. HIPAC Mk-1 processor had a capability of multiple address modification by 3 index registers and the instruction address register.
In June 1959, UNESCO held the 1st International Conference of Information Processing in Paris. Takada and Kayashima attended the Conference and exhibited, at the AUTO-MATH 1959 held in conjunction with the Conference, HIPAC101, an improved model of HIPAC Mk-1.
In Feb. 1960, he moved from the Central Research Laboratory to Totsuka Works of Hitachi, where the Company launched its computer business. In August 1962, Hitachi established Computer Division and its Kanagawa Works. Kayashima, as a Kanagawas design engineer, was responsible for designing the parametron computer HIPAC101, and its successor, HIPAC103.
After Takahashi Shigeru moved to Hitachi from the ETL, Kayashima participated in developing new series of computers, HITAC8000, based on the technical licensing from RCA. He joined the Hitachi-RCA cooperation project at West Palm Beach, Florida to develop RCA Spectra70/35. The project turned out a success, resulting in HITAC8300 computer.
In May 1969, he began participation in DIPS Project, which was a joint effort of NTT, NEC, Hitachi and Fujitsu to develop a series of computers to be used by NTT for data communication services. Kayashima was responsible to develop DIPS1-L(H), Hitachi Version of DIPS, succeeded in shipping it in time to NTT Musashino Telecommunications Laboratory in June 1971.
In 1979, he was appointed the General Manager of Asahi Works of Hitachi, where he managed developing and producing mini-computers, office computers and data terminals. In 1984, he was assigned to the Chief Engineer of Computer Division of Hitachi, and in 1985, he retired from the Company.
Then, Kayashima was appointed Managing Director of Hitachi Electronics Engineering Company (Hitachi DECO). From June 1993 to June 1999, he was the President of this Company. In 1999, he was assigned to its CEO, and in 2001 to its Adviser. He retired from Hitachi DECO in 2002.
Kayashima served as the Director /Senior Director of the Information Processing Society of Japan (ISPJ) in 1976/77.
He died on June, 2018.