The Busicom Engineering Prototype Calculator Home   Back The Intel 4004 Microprocessor and the Silicon Gate Technology A testimonial from Federico Faggin, designer of the 4004 and developer of its enabling technology Photograph of Faggin with the original engineering prototype of the Busicom desktop printing calculator. The Busicom Engineering Prototype Calculator This is a picture of the original engineering prototype of the Busicom desktop printing calculator, the world’s first commercial product to use a microprocessor. The microcomputer that powered the calculator used five 4001’s, two 4002’s, three 4003’s and the 4004 CPU. The one and only engineering prototype calculator was a personal gift to Faggin, as the leader of the 4004 project, by Busicom’s President, Mr. Yoshio Kojima, in recognition of his successful job. Faggin donated it to the Computer History Museum in Silicon Valley in 1996. Photo of the original engineering prototype of the Busicom desktop printing calculator.