TAC Williams Tube, a Vacuum Tube and Related Materials

TAC Williams Tube

TAC Williams Tube



TAC a Vacuum Tube

TAC a Vacuum Tube



TAC Programming Manual・Report on the TODAI AUTOMATIC COMPUTER

TAC Programming Manual・Report on the TODAI AUTOMATIC COMPUTER



Manufactured in 1959
Manufactured by The University of Tokyo
Owner Department of Computer and Information Sciences, Tokyo University of Agriculture Technology
Location of historical materials Department of Computer and Information Sciences, Tokyo University of Agriculture Technology 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588
Visitor information Not open to the public (Ask for a visit)
Contact Tokyo University of Agriculture Technology
Professor Keiichi Kaneko Tel.+81-43-388-7155 http://www.tuat.ac.jp/


TAC stands for Todai Automatic Computer. This is a vacuum tube computer developed by the University of Tokyo (Todai) in 1959. In 1951, a general-research group called "Electronic Computer Research" was formed at the University of Tokyo, with a science and technology research grant from the Ministry of Education. The research was conducted by the group leader Hideo Yamashita.

In 1952 eleven million yen grant was given to the University of Tokyo for this project and the research was continued by a team centered around Ayao Amemiya. Basic logic specification was developed by the University of Tokyo and the hardware manufacturing was ordered Tokyo Shibaura Electric (TOSHIBA). Detail design was implemented by Shigeru Mita et. al. of Toshiba. The prototype was manufactured and was installed at the Engineering Research institute of the University of Tokyo in late 1954.

Adjustments, which began in the following year (1955), ran into trouble. After 1956, Kenro Murata and Kisaburo Nakazawa of University of Tokyo redesigned the system and reformed it and the machine was completed in February, 1959. It was used in many research projects until operation was stopped in 1962.

TAC is a binary serial computer with the EDSAC instruction set. For instructions, it used a 17-bit short word, and for numerical values a 35-bit long word. Main memory capacity was 1,024 short words (512 long words).

TAC used 7,000 vacuum tubes and 3,000 diodes. The random access system, using 16 Williams tubes (cathode ray tubes), was employed in the main memory unit, and this enabled high-speed memory write and read. At first only a fixed point arithmetic unit was implemented but in in June 1959 a floating point arithmetic unit was provided in hardware. This machine was an earliest adopter of the index register in Japan, which was used for the first time in the EDSAC II.