Masatoshi Shima
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The Intel 4004 Microprocessor and the Silicon Gate Technology
A testimonial from Federico Faggin, designer of the 4004 and developer of its enabling technology
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Busicom
The 4000 Family
Masatoshi Shima
Masatoshi Shima was the engineer responsible for the Busicom calculator design. He came from Japan a few days after Faggin joined Intel, to check the logic design of the chip set. He was dismayed and very angry to see that Hoff's proposal had not progressed from his last visit, six months before, against Intel's promises. He stayed on and helped Faggin with the detailed logic design to partially recover the delay in the schedule agreed upon six months before. Besides Shima, the other members of the 4000 family design team were one electronic technician, and three draftsmen, of which only one knew how to layout silicon gate devices.

Masatoshi Shima was a software and logic engineer with practically no knowledge of MOS process technology and MOS circuit and chip design. During the first six months of the MCS-4 development, he stayed at Intel to check on the project development and was the only engineer helping Faggin during the design phase of the chips. Shima took directions and learned from Faggin, while completing various tasks being assigned to him. Shima's contributions were fairly routine tasks that any good engineer could have accomplished.

On page 74 of his book "The Birth of the Microcomputer: My Recollections," Published in August 1987 by Iwanami Shoten, Tokyo, Shima says: "Mr. Faggin taught me the semiconductor process, circuitry design, layout designů. Since April I worked with Mr. Faggin in the same room and I learned a lot from him, then because of that, I could build up the basis as LSI engineer for later use. In this over 6 months period I learned circuitry techniques based on the layout which is most important basis of LSI design and I also learned how to use the mask design and I learned the methodology of LSI development and also how challenging and creative job excites the engineer and also that success bring big joy and also big money. So I learned all of this through the job of 6 months. For me developing 4004 with Mr. Faggin, for better or worse, was more than doing drugs and even now I feel my blood run backwards. Even now when I look at LSI development for new application field all my blood feels like going backward."

In 1970, the architecture and logic design of a simple CPU had been done many times before, becoming fairly routine tasks. What had not been done before was to creatively do the circuit design and the layout of such a complex chip as the 4004 to fit into a small enough chip to be commercially viable. That was Federico Faggin's key contribution, made possible by his intimate knowledge of the MOS silicon gate technology he developed at Fairchild Semiconductor two years before. Faggin was also very familiar with computer architecture and with logic design since he had co-developed and built an early experimental electronic computer at Olivetti R&D Labs in Italy before coming to the US.