Matsuzaki Isokazu was born on July 3, 1927, and graduated from Musashi College of Technologies in 1949. He soon joined Electrotechnical Laboratory of MITI (Ministry of International Trade and Industry) and started his career of engineering scientist with ETL's Materials Research Division. He was assigned to Materials Measurement laboratory headed by Takahashi Shigeru. Nakajima Tatsuji, Nishino Hiroji, Kondo Kaoru and others were his colleagues there. Matsuzaki was excellent at manufacturing tangible equipment, and talented in making a careful observation in experiments and measurements. An equipment to read out immediately dielectric loss coefficient, which Matsuzaki manually completed, was made a commercial product by Nisshin-Denki. A Transformer Bridge, on which he elaborated, was made a popular commercial product by Ando-Denki.
When Electronics Division launched in July 1954 within the ETL, Matsuzaki was assigned to this new Division together with Takahashi Shigeru, Nishino Hiroji and Kondo Kaoru from Materials Research Division. At the beginning, they interested themselves in measuring various characteristics of transistors that had only recently become available for samples. In November 1954, however, Takahashi and Wada Hiroshi, Head of the Division decided to develop a transistor computer.
The storage unit of this computer named ETL Mark III was a supersonic delay-line through a medium of hard glass, and made by Kinseki-sha. Takahashi assigned Matsuzaki to develop a circuit to amplify, reshape and synchronize pulses to be stored in this delay-line, and assumed this was an easy task for him. However, it did not proceed as anticipated, and Matsuzaki had a hard time for about two weeks to find out what the problem was. One day, however, he suddenly shouted, "Oh yes, pulses could come at anytime. Should not use self-bias!" Not being talkative, Matsuzaki rarely shouted like this, but he could understand at that time the inherent characteristics of digital circuits. After that, the machine debugging proceeded smoothly, and ETL Mark III was completed in July 1956. It was the second stored program computer, and the first transistor computer, in Japan.
Based on the self-confidence acquired by the speedy completion of Mark III, Takahashi's group started to develop ETL Mark IV computer with the use of junction transistors (Mark III used early unreliable transistors of point contact type). The slower junction transistors required slower storage unit, and a high-speed magnetic drum was adopted instead of supersonic delay-lines. Matsuzaki was assigned to develop peripheral circuits of the drum. ETL Mark IV was completed in November 1957, not more than one and half years after the completion of the Mark III. The technology of the Mark IV were transferred to NEC, Hitachi Hokushin-Denki, Matsushita Communications Industry, and others, and helped in great deal the Japanese Computer Industry develop.
In October 1962, Matsuzaki left the ETL and joined Hitachi. He worked mostly at Kanagawa Plant. The most remarkable contribution Matsuzaki made to Hitachi was the development of ROM (Read-only Memory). He invented a ROM consisting of sheets of thin plastic film and ferrite cores of EI shape. When it was about to be decided to employ this ROM for HITAC 8400 computer, IBM Japan announced System/360 Model 40, and exhibited a part of its hardware at the Prince Hotel in Akasaka. Takahashi saw this display and found that it was almost similar to Matsuzaki's ROM. He immediately called Matsuzaki to the Hotel. Only difference of IBM's ROM from Matsuzaki's was that it used cores shaped like UI instead of EI. Matsuzaki inspected the IBM's ROM through display window for about an hour, and realized its merit. He altered the design of HITAC 8400 ROM, and the similar design was employed for all the early models of HITAC 8000 series. DIPS-1L that Hitachi developed employed high-speed ROM consisting of resistors. Matsuzaki was responsible also for its design.
Matsuzaki retired from Hitachi in 1983, and joined Minato Electronics. When the position of a Director of the Board was offered, he declined it, stating that it is not a job suitable for him. After leaving this Company, he taught at Nihon-Kogakuin College at Kamata, but died of pancreatic cancer rather suddenly on April 6, 1993.
Matsuzaki always preferred to be inconspicuous wherever he went. However, without his devotion in and talent for the job, the speedy completion of, for instance, ETL Mark III must have been very difficult.