Japanese Computer Pioneers

Yajima ShuzoYajima Shuzo

Yajima Shuzo was born on December 6, 1933. He graduated from the Department of Electrical Engineering, Faculty of Engineering, Kyoto University in 1956, and completed his Master’s Degree at the Department of Electrical Engineering, Graduate School of Engineering in 1958. Immediately after he became a Ph.D candidate, he was dispatched to Totsuka Works of Hitachi, Ltd. to participate in the development of Kyoto University's first digital all-purpose electronic computer, KDC-I (Kyoto Daigaku Digital Computer - I) also known as HITAC 102B, for the Ministry of Education's research project led by his supervisor, Professor Maeda Ken-ichi. Referring to the ETL Mark V also known as HITAC 102A, which was under development at Hitachi, the KDC-I was developed in parallel with the ETL Mark V , as a germanium transistor- based computer. KDC-I was a pioneering commercial machine, in that it has both a magnetic core memory and a magnetic tape unit, as well as an extended instruction set including detailed floating-point arithmetic operations especially designed for scientific and engineering calculations. For nearly two years, Yajima focused his energy on the coordination and arrangement for the logic design and the design of the magnetic tape unit as well as their development, and finally succeeded in running the core part at the end of 1959. At that time, Yajima implemented a computer program to solve the routing problem of logic designs and executed the computer program as a test program on KDC-I, which was an early CAD (computer-aided design) program. During the development of the machine, he also invented and developed a certain kind of logic tester to measure the margins of transistor circuits, which was later commercially manufactured.

Upon the completion of KDC-I, Yajima returned to Kyoto University in the summer of 1960. KDC-I was the first transistor- based computer in Japanese universities. The machine was also commercially manufactured as HITAC 102B and was introduced to certain institutes such as the Economic Planning Agency of Japan. In 1961, the first computation center among Japanese universities was established at Kyoto University, where the shared use of KDC-I started. For approximately 15 years many students and teachers used the machine. KDC-I received technical achievement at the Electrotechnical Laboratory, and, owing to the intelligence and passion of Hitachi's engineers and Kyoto University's teachers and graduate students, KDC-I finally came to fruition. The machine was truly "the crown of a government-industry-academia collaboration". The success of KDC-1 cannot be mentioned without also mentioning Yajima's role in the project. His notes on design and development, his diaries, records, drawings of logic designs, manufacturing drawings and notes on arrangements, were donated to Kyoto University Archives in 2004. These documents turned out to be uncommonly useful in passing down the processes of the technological developments of those days.

In 1961, Yajima became a research associate at the Department of Electronics, Faculty of Engineering, Kyoto University. After he served as a lecturer and an associate professor, he took charge of the Laboratory of Logic Circuits and Automata as professor at the Department of Information Science in 1971. In 1976, he developed the computer network, LABOLINK, with Sumitomo Electric Industries, Ltd., which linked computers via optical fibers, and, in 1977, he also developed the relational database system ARIS. Both are pioneering achievements in their related fields. Yajima obtained a patent on a graphic system for logic CAD for which he had carried out the research and development. Around 1987, related to logic CAD, Yajima started to boost research on binary decision diagrams. As for theoretical research, he also has many achievements in various fields such as logic circuit theory, automaton theory, logic CAD, logic design verification, logic circuit algorithms, and computational complexity theory, from which not a few ideas have come into practical use. Many students who did research in these fields under Yajima's supervision have contributed to the establishment of many fields of computer and information science from theory to practice such as VLSI design technology, database technology, computational complexity theory, and algorithm theory. Many of Yajima's students have taken positions at Japanese universities including more than 10 as professors. It is particularly worth noting Yajima's foresight in pioneering new fields, and his contribution to educating young people in Japan in the area of information science and computer science.

After retiring from Kyoto University in 1997, Yajima served as a professor at Kansai University, and was appointed Chairperson of the Graduate School of Informatics. He also served as Director of the Research Center for Advanced Informatics in 2005. He has obtained about 50 patents including approximately 10 KDC-I related patents. Many pioneering papers have been published in journals and transactions of Japanese academic societies and of IEEE, and in the proceedings of international conferences. He is an IEICE Fellow and an IEEE Life Fellow. In the Information Processing Society of Japan, Yajima also served as a Trustee, a Managing Trustee and Chairperson of the IFIP Committee in 1978 and 1979, and also contributed to the establishment of the Journal of Information Processing.

(Kikuno Tohru)
(As of Sep. 14, 2006)