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Masatoshi Shima: Wikis


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Masatoshi Shima (嶋正利 Shima Masatoshi, born on August 22, 1943 in Shizuoka, Japan) was one of the designers of the world's first microprocessor, the Intel 4004, along with Ted Hoff, Stanley Mazor, and Federico Faggin.

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 by Intel to design the next microprocessor, which became the Intel 8080 (it is unclear if Shima also was involved in creation of 8088 and 8086). Later, Shima moved to Zilog to develop the Z80, which he made instruction compatible with Intel 8080. This was followed by the 16-bit Z8000.[1]

According to co-workers from Intel, Shima designed all logic at the transistor level 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,[2] 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.



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