Revision as of 09:27, 3 July 2019

Busicom, formerly known as Nippon Calculating Machine Corp, is a now-defunct Japanese high-end desktop calculator maker best known for their partnership with Intel that resulted in the world's first commercial microprocessor.

It owned the rights to the first commercial microprocessor, the Intel 4004, which began as the "Busicom Project" in 1968, before being developed as a single-chip microprocessor in partnership with Intel from 1969 to 1970.

History

Japan has had a long tradition of mathematics and calculator building dating back to as early as 1902. March that year, Ryōichi Yazu applied for a patent on his mechanical calculator, Japan's first mechanical calculator. In 1906, the Japanese Ministry of Communications and Transportation built an electronic calculator.

In 1945, a company by the name Nippon Calculating Machine Corp was founded to build calculators. The company was later renamed Business Computer Corporation - Busicom in 1967. At the same time the company was also developing a brand of electronic calculators called Busicom. During the spring of 1969 Intel had a MOS team that was working on silicon-gate memory.

Microprocessor

In April 1968, engineer Masatoshi Shima was tasked with designing a special-purpose LSI chipset, along with his supervisor Tadashi Tanba, for use in the Busicom 141-PF desktop calculator.^[1][2] This later became known as the "Busicom Project".^[3] His initial design consisted of seven LSI chips, including a three-chip CPU.^[3] His design included arithmetic units (adders), multiplier units, registers, read-only memory (ROM), and a macro-instruction set to control a decimal computer system.^[1] Busicom then wanted a general-purpose LSI chipset, for not only desktop calculators, but also other equipment such as an automatic teller machine (ATM), cash register and billing machine. Shima thus began work on a general-purpose LSI chipset in late 1968.^[2]

People who were influential in the development of the microprocessor were Sharp engineer Tadashi Sasaki and Intel founder Robert Noyce. Sasaki conceived of a single-chip CPU in 1968, when he discussed the concept at a brainstorming meeting that was held in Japan. Sasaki attributes the basic invention to break the calculator chipset into four parts with ROM (4001), RAM (4002), shift registers (4003) and CPU (4004) to an unnamed woman, a software engineering researcher from Nara Women's College, who was present at the meeting. Sasaki then had his first meeting with Noyce in 1968, and presented the woman's four-division chipset concept to Intel and Busicom.^[4]

In 1969, Busicom contacted a Silicon Valley company called Intel to help develop a microprocessor for its high-end calculator, the 141-PF calculator. At the time, Intel was only a memory company. Working with Busicom on their chips was orthogonal to Intel's primary business.

In 1969, Busicom asked Intel, a company founded one year earlier in 1968 for the purpose of making solid state random-access memory (RAM), to finalize and manufacture their calculator engine. Intel, which was more of a memory company back then, had facilities to manufacture the high density silicon gate MOS chip Busicom required.^[2]

At the time, Busicom was looking to develop a set of 12 specialized chips, each consisting of 3,000 to 5,000 transistors. Busicom planned on sending a team of engineers to Intel to design the chips on-site and have Intel manufacture its calculator chip sets for roughly $100,000. Busicom expected Intel to manufacture at least 60,000 of them and buy them for $50 each. The Busicom engineering group arrived in California at the end of June 1969. Soon after arriving, the concept of 12 chips proved to be very complex - 1 chip was to be used exclusively to store values, another was to interface with the keyboard, another to interface with the screen.

Shima went to Intel in June 1969 to present his design proposal. Due to Intel lacking logic engineers to understand the logic schematics or circuit engineers to convert them, Intel asked Shima to simplify the logic.^[2] Intel wanted a single-chip CPU design,^[2] influenced by Sharp's Tadashi Sasaki who presented the concept to Busicom and Intel in 1968.^[4]

The single-chip microprocessor design was then formulated by Intel's Ted Hoff in 1969,^[3] simplifying Shima's initial design down to four chips, including a single-chip CPU.^[3] Marcian Hoff, an employee at Intel proposed an alternative scheme where a single general-purpose chip would do the bulk of the work.

Hoff was assigned to studying Busicom's design, and formulated a simpler, 4 ICs architecture centered on what was to become the 4004 microprocessor.^[5] Hoff's design was more elegant, requiring just four chips, memory, a shift register, and a general purpose chip.

Due to Hoff's formulation lacking key details, Shima came up with his own ideas to find solutions for its implementation. Shima was responsible for adding a 10-bit static shift register to make it useful as a printer's buffer and keyboard interface, many improvements in the instruction set, making the RAM organization suitable for a calculator, the memory address information transfer, the key program in an area of performance and program capacity, the functional specification, decimal computer idea, software, desktop calculator logic, real-time I/O control, and data exchange instruction between the accumulator and general purpose register. Hoff and Shima eventually realized the 4-bit microprocessor concept together, with the help of Intel's Stanley Mazor to interpret the ideas of Shima and Hoff.^[2] The specifications of the four chips were developed over a period of a few months in 1969, between an Intel team led by Hoff and a Busicom team led by Shima.^[3]

Busicom's management agreed to the new proposal,^[6] and the chips' implementation was then led by Federico Faggin who had previously developed the Silicon Gate Technology at Fairchild Semiconductor. It was this technology that made the design of the microprocessor and the dynamic RAMs a reality. The 4 ICs were delivered to Busicom in January 1971.^[7]

References