Japanese Computer Pioneers

Shima MasatoshiShima Masatoshi

Shima Masatoshi was born at Shizuoka on August 22, 1943. He graduated from Department of Chemistry, Faculty of Science, Tohoku University in March 1967, and then he joined Busicom Corporation. Shima started to work as a programmer at computer division, learning several programming languages. In October 1967, Shima moved to desktop calculator division, and then took charge of manufacturing for trial a desktop calculator which was implemented by the hardwired logic design method. In those days, OEM business for desktop calculator grew up very rapidly in Japan. Busicom started to look for new logic design method that would be much more suitable for OEM business. In November 1968, Shima developed new desktop calculator with printer, introducing decimal computer's instruction set architecture and ROM based stored program method.

In early 1969, Busicom decided to develop a general-purpose LSI family that would be used for not only a desktop calculator but also business machines such as a billing machine, a cash register and a tellers machine. Busicom chose Intel Corporation as a co-developer since Intel had an advanced silicon gate MOS process technology. In June 1969, Shima went to the States with a proposal and started to discuss with Intel engineer, M.E.Hoff, showing the proposed logic schematic. Hoff agreed to the proposed stored program method, but did not agree to the decimal computer architecture since its logic looked very complicated for him. After many discussions, in August 1969, a 4-bit binary computer's architecture was proposed by Hoff. He showed only three boxes such as a 4-bit ALU, an 8/16 sets of 8/4-bit general purpose register file and a 4 levels of stack with a program counter. However, his proposal was only framework, and many problems were surfaced. At that time, the scientific desktop calculator had many peripherals such as a keyboard, a card reader for application program loader, a CRT display, and a printer. The most difficult problem to be solved was how to control many peripherals under real time manner by program, using a slow 4-bit binary processor and a slow memory. Also, 16 pin package had to be used since Intel was a memory company. In order to solve those problems, at first, it was agreed that a time shared 4-bit width system bus was introduced, and the 4004 system was composed by only four kinds of LSI such as 4004 CPU, 4001 ROM for program, 4002 RAM for data, and 4003 IO-Expander. Next, the 4004 instruction set was examined and optimized in order to satisfy application specific requirements in performance and memory, developing various application programs to be critical. In December 1969, a concrete plan for the 4004 system was finalized. An actual chip design started in April 1970. Shima took charge of 4004 CPU logic design, layout check and test program generation. The world first microprocessor 4004 development was finally completed in March 1971. A total transistor number of 4004 CPU was 2,300 and its chip size was 12 square mm. The 4004 CPU achieved 0.065 MIPS performance at 750KHz operating frequency. In 1971, Shima developed a desktop calculator with printer, using the 4004 system with 1 K bytes of ROM.

Shima joined Ricoh in September 1971, and then had various important development experiences such as an interface between mini-computer and I/O typewriter, a channel controller between Main Frame and a graphical mini-computer, an electronic control for high-speed printer, and a drum tester with 8-bit mini-computer. All of these development experiences became the basis of 8-bit microprocessor development.

Shima joined Intel in November 1972, and then developed 8-bit microprocessor 8080 in January 1974. A total transistor number of 8080 was 5,500 and its chip size was 19.6 square mm. The 8080 microprocessor achieved 0.33 MIPS performance at 2 MHz operating frequency. After the success of 8080 development, Shima developed various 8080 peripheral chips, which some of them were used in IBM personal computer, such as 8259 interrupt controller chip, 8255 parallel port chip, 8253 timer chip, 8257 DMA chip, and 8251 serial communication USART chip as a department manager.

Microprocessors, which became the "break through technology" to open up a new era, had two outstanding impacts, an intelligent power and a calculating power. First, microprocessors opened up a new "era of program" through replacing hardware with software. This led to the development of "intelligent" microcontrollers. Next, microprocessors allowed young engineers to access to the power of microprocessors, encouraging the creative development of personal computers and computer games, which in turn led to growth in the software industry, and paved the way to the development of high-performance microprocessors.

Shima developed 8-bit microprocessor Z80 in 1976 and 16-bit microprocessor Z8000 in 1979 at Zilog. In 1980, Shima came back to Japan and established Intel Japan Design Center as a director. In 1986, Shima co-founded VM Technology Corporation, and then developed 16-bit microprocessor VM860 and 32-bit microprocessor VM 8600 whose instruction sets are compatible with Intel x86 microprocessors, for Japanese word processor market. The microprocessor development in his young days resulted in his Doctor's Degree from the University of Tsukuba in March 1992. In April 2000, Shima became Professor at the University of Aizu.

Main awards:

- The Kyoto Prizes (1997 Advanced Technology Category)
- "Inventor of MPU (Micro Processor Unit)"
A salute to the 50th Anniversary of the Semiconductor Industry, 1998

(As of June 14, 2004)