Masatoshi Shima

Masatoshi Shima (嶋 正利, Shima Masatoshi^?, born August 22, 1943) is a Japanese electronics engineer, who was one of the designers of the world's first microprocessor, the Intel 4004, along with Federico Faggin, Ted Hoff, and Stanley Mazor.

He studied organic chemistry at Tohoku University in Sendai, Japan. With poor prospects for employment in the field of chemistry, he went to work for Busicom, a business calculator manufacturer. There, he learned about software and digital circuit design. When Busicom decided to use LSI circuits in their calculator products, they approached the American companies Mostek and Intel for manufacturing help. The job was given to Intel, who back then was more of a memory company and had facilities to manufacture the high density silicon gate MOS chip Busicom required. Following Marcian "Ted" Hoff's initial conception, Shima designed the 4004 processor at the Intel offices with Hoff and Federico Faggin. His company then sold the rights to use the 4004 to Intel, with the exception of use in business calculators.

Intel then designed the 8008 on their own, but the chip was a commercial failure due to various reasons. Shima was then employed to implement the transistor-level logic of Intel's next microprocessor, which became the Intel 8080 (he was not involved in creation of 8088 and 8086). Shima moved to Zilog in 1975 and, using only a small number of assistants,^[1] developed the transistor-level and physical implementation of the Z80, which Faggin had made instruction compatible with Intel 8080. This was followed by the same task for the 16-bit Z8000.^[2]

According to co-workers from Intel, Faggin's method that Shima used was to design all logic at the transistor level directly and manually (not at the gate and/or register level). The schematics were therefore hard to read, but as transistors were drawn in such a way that they suggested a "floorplan" of the chip,^[3] it actually helped when making the physical chip layout. However, according to Shima himself, the logic was first tested on breadboards using TTL chips, before being manually translated into MOS transistor equivalents.

Prizes

• 1997 Kyoto Prize (Advanced Technology)
• 2009 Fellow of the Computer History Museum

Notes

1. ^ Zilog had a total of 11 employees at the time, but grew to more than 1000 in a very short time.
2. ^ Masatoshi Shima
3. ^ Monte Dalrymple to Peter Alfke : comp.lang.vhdl

External links

• Interview with Masatoshi Shima regarding his role in the design of the 4004

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Name	Shima, Masatoshi
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Date of birth	1943
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