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Intel 4004
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White ceramic Intel C4004 microprocessor with grey traces
Produced From 1971 to 1981
Common manufacturer(s)
  • Intel
Max. CPU clock rate 740 kHz
Min. feature size 10 μm
Instruction set 4-bit BCD-oriented
Transistors 2300
Data width 4
Address width 12 (multiplexed)
Successor Intel 4040
Intel 8008
Application Busicom calculator, arithmetic manipulation
  • 16-pin DIP

The Intel 4004 is a 4-bit central processing unit (CPU) released by Busicom and Intel Corporation in 1971. It was the first commercially available microprocessor.[1] It began as the "Busicom Project", a joint development by Japan's Busicom and America's Intel,[2][3] with initial design concepts by Busicom's Masatoshi Shima and Sharp's Tadashi Sasaki in 1968,[4][5][2] before being designed by Busicom's Shima and Intel's Marcian Hoff and Federico Faggin from 1969 to April 1970;[2][3][6] it was completed under the leadership of Shima and Faggin in January 1971. The first commercial sale of the fully operational 4004 occurred in March 1971 to Busicom, for the Busicom 141-PF calculator, for which it was originally designed and built as a custom chip.[6] In mid-November of the same year, with the prophetic ad "Announcing a new era in integrated electronics", the 4004 was made commercially available to the general market.

The 4004 is history’s first monolithic CPU, fully integrated in one small chip. Such a feat of integration was made possible by the use of the then-new silicon gate technology which allowed twice the number of random-logic transistors and an increase in speed by a factor of five compared to the incumbent technology. The 4004 microprocessor is one of 4 chips constituting the MCS-4 chip-set, which includes the 4001 ROM, 4002 RAM, and 4003 Shift Register. With these components, small computers with varying amounts of memory and I/O facilities can be built. The MCS-4 was eventually superseded by powerful microcontrollers like the Intel 8048 and the Zilog Z8 in 1978-1979. The architecture of this processor formed the basis for later models of microprocessors.

History and production[]


The origins of the 4004 date back to the the "Busicom Project",[3] which began at Japanese calculator company Busicom in April 1968, when 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 with integrated printer.[4][2] 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, and a macro-instruction set to control a decimal computer system.[4] Busicom then wanted a general-purpose LSI chipset, for not only desktop calculators, but also other equipment such as a teller machine, cash register and billing machine. Shima thus began work on a general-purpose LSI chipset in late 1968.[2]

Sharp engineer Tadashi Sasaki was also involved with its development, and conceived of a single-chip microprocessor 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 Robert Noyce from Intel in 1968, and presented the woman's four-division chipset concept to Intel and Busicom.[5]


Busicom approached the American company Intel for manufacturing help in 1969. Intel, which was more of a memory company back then, had facilities to manufacture the high density silicon gate MOS chip Busicom required.[2]

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.[5] The single-chip microprocessor design was then formulated by Marcian Hoff in 1969,[3] simplifying Shima's initial design down to four chips, including a single-chip CPU.[3] Hoff, head of Intel's Application Research Department, contributed to the architectural proposal for Busicom.

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]

In late 1969, Shima returned to Japan.[2] After that, Intel had done no further work on the project until early 1970.[2][3]


Shima returned to Intel in early 1970, and found that no further work had been done on the 4004 since he left, and that Hoff had moved on to other projects.[2] Only a week before Shima had returned to Intel,[2] Federico Faggin had joined Intel and become the project leader.[3] After Shima explained the project to Faggin, they worked together to design the 4004.[2]

Shima designed the logic[2] and the Busicom calculator firmware, and assisted Faggin during the first six months of the implementation. The manager of Intel's MOS Design Department was Leslie L. Vadász.[7] At the time of the MCS-4 development, Vadasz's attention was completely focused on the mainstream business of semiconductor memories and he left the leadership and the management of the MCS-4 project to Faggin.

Thus, the chief designers of the chip were Shima who produced the initial Busicom design and then assisted in the development of the final Intel design,[4] Faggin who created the design methodology and the silicon-based chip design, and Hoff who formulated the architecture before moving on to other projects.


The 4004 was first introduced in Japan, as the microprocessor for the Busicom 141-PF calculator, in March 1971.[2][4] In North America, the first public mention of the 4004 was an advertisement in the November 15, 1971 edition of Electronic News,[8] though unconfirmed reports put the date of first delivery as early as March 1971. Packaged in a 16-pin ceramic dual in-line package, the 4004 was the first commercially available computer processor designed and manufactured by chip maker Intel, which had previously made semiconductor memory chips. The 4004 was followed the next year by the first 8-bit microprocessor, the 3,500 transistor 8008 (and the 4040, a revised and improved 4004). It was not until the development of the 40-pin 8080 in 1974 that the address and data buses would be separated, giving faster and simpler access to memory.


The first commercial product to use a microprocessor was the Busicom calculator 141-PF. Busicom also used it for other equipment such as a teller machine, cash register and billing machine. Shima thus began work on a general-purpose LSI chipset in late 1968.[2]

The 4004 was also used in the first microprocessor-controlled pinball game, a prototype produced by Dave Nutting Associates for Bally in 1974.

According to Federico Faggin in a lecture for the Computer History Museum in 2006, the Pioneer 10, the first spacecraft to leave the solar system, used an Intel 4004 microprocessor.[9]


  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Masatoshi Shima, IEEE
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Federico Faggin, The Making of the First Microprocessor, IEEE Solid-State Circuits Magazine, Winter 2009, IEEE Xplore
  4. 4.0 4.1 4.2 4.3 4.4 Nigel Tout. The Busicom 141-PF calculator and the Intel 4004 microprocessor. Retrieved on November 15, 2009.
  5. 5.0 5.1 5.2 Aspray, William (1994-05-25). Oral-History: Tadashi Sasaki. Interview #211 for the Center for the History of Electrical Engineering. The Institute of Electrical and Electronics Engineers, Inc.. Retrieved on 2013-01-02.
  6. 6.0 6.1 Faggin, F. (1992). "The Birth of the Microprocessor". Byte, pp. 145–150, March 1992.
  7. The Intel4004. Retrieved on 2008-03-15.
  8. Gilder, George (1990). Microcosm: the quantum revolution in economics and technology. Simon and Schuster. p. 107. ISBN 978-0-671-70592-3. "Intel's first advertisement for the 4004 appeared in the November 15, 1971 issue of Electronic News," 
  9. Intel 4004 Microprocessor 35th Anniversary. Computer History Museum (2006-11-13). Retrieved on 2011-07-06.

Historical documents[]

  • Faggin F., Capocaccia F. "A New Integrated MOS Shift Register”, Proceedings XV International Electronics Scientific Congress, Rome, April 1968, pp. 143–152. This paper describes a novel static MOS shift register, developed at SGS-Fairchild (now ST Micro) at the end of 1967, before Federico Faggin joined Fairchild's R&D in Palo Alto (Ca) in February 1968. Faggin later used this new shift register in the MCS-4 chips, including the 4004.
  • Cover and abstract of the IEDM (International Electron Devices Meeting) Program (October 1968). The Silicon Gate Technology (SGT) was first presented by its developer, Federico Faggin, at the IEDM on October 23, 1968 in Washington, D.C. It was the only commercial process technology for the fabrication of MOS integrated circuits with self-aligned gate that was later universally adopted by the semiconductor industry. The SGT was the first technology to produce commercial dynamic RAMs, CCD image sensors, non volatile memories and the microprocessor, providing for the first time all the fundamental elements of a general purpose computer with LSI integrated circuits.
  • Cover of Electronics Magazine (September 29, 1969). The Electronics article introduces the Fairchild 3708, designed by Federico Faggin in 1968. It was the world's first commercial integrated circuit using the Silicon Gate Technology, proving its viability.
  • Initials F.F. (Federico Faggin) on the 4004 design (1971). The 4004 bears the initials F.F. of its designer, Federico Faggin, etched on one corner of the chip. Signing the chip was a spontaneous gesture of proud authorship and was also an original idea imitated after him by many Intel designers.
  • Busicom 141-PF Printing Calculator Engineering Prototype (1971). (Gift of Federico Faggin to the Computer History Museum, Mountain View, CA). The CHM collection catalog shows pictures of the engineering prototype of the Busicom 141-PF desktop calculator. The engineering prototype used the world’s first microprocessor to have ever been produced. This one-of-a-kind prototype was a personal present by Busicom’s president Mr. Yoshio Kojima to Federico Faggin for his successful leadership of the design and development of the 4004 and three other memory and I/O chips (the MCS-4 chipset). After keeping it in his home for 25 years, Faggin donated it to the CHM in 1996.
  • F. Faggin and M.E. Hoff: "Standard parts and custom design merge in four-chip processor kit". Electronics/April 24, 1972, pp. 112–116. Reprinted on pp. 6–27 to 6–31 of The Intel Memory Design Handbook: August 1973.
  • F. Faggin, M. Shima, M.E. Hoff, Jr., H. Feeney, S. Mazor: "The MCS-4—An LSI micro computer system". IEEE '72 Region Six Conference. Reprinted on pp. 6–32 to 6–37 of The Intel Memory Design Handbook: August 1973.

Further reading[]

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