Computer History MuseumSemiconductor History

1971 - Microprocessor Integrates CPU Function onto a Single Chip

Silicon-gate process technology and design advances squeeze computer central processing units (CPU) onto single chips.

By the late-1960s, designers were striving to integrate the central processing unit (CPU) functions of a computer onto a handful of MOS LSI chips, called microprocessor unit (MPU) chip sets. Building on 8-bit arithmetic logic units (3800/3804) he designed earlier at Fairchild, in 1969 Lee Boysel created the Four-Phase Systems Inc. AL-1 an 8-bit CPU slice that was expandable to 32-bits. In 1970 Steve Geller and Ray Holt of Garrett AiResearch designed the MP944 chip set to implement the F-14A Central Air Data Computer on six metal-gate chips fabricated by AMI.

Intel's first microprocessor, the 4004, was conceived by Ted Hoff and Stanley Mazor. Assisted by Masatoshi Shima, Federico Faggin used his experience in silicon-gate MOS technology (1968 Milestone) to squeeze the 2300 transistors of the 4-bit MPU into a 16-pin package in 1971. Faggin also supervised Hal Feeney's design of the 8-bit 8008 device announced in 1972. Designed for CTC (later Datapoint), prototypes of the 8008 function were also built by Texas Instruments as the TMX1795 but never offered commercially. Second generation 8-bit designs from Intel (8080) and from a team led by Tom Bennett at Motorola (6800) in 1974 established widespread acceptance of the MPU concept. A low-cost variant on the 6800 architecture by MOS Technology (6502) enabled personal computers and games from Apple, Atari, Commodore and others. By the mid-1970s many vendors offered enhanced 8-bit architectures, with Zilog's Z80 being the most enduring. Two 1975 MPUs that presaged important later trends included RCA's CMOS COSMAC 1802 (1963 Milestone) and John Cocke’s 801 RISC device at IBM.

Beginning in the mid-1970s, 16-bit MPUs emerged from General Instrument (CP1600), National (PACE), TI (TMS9900), and Zilog (Z8000). Boosted by the PC boom of the 1980s, Intel's 8086/8088 (IBM PC) and Motorola's 68000 (Macintosh) devices enjoyed the widest market success.



Contemporary Documents

Sack, E. A., Lyman R. C. and Chang, G. Y. "Evolution of the Concept of a Computer on a Slice," Proceedings of the IEEE , vol. 52, no. 12, (December 1964) pp. 1713-20.

Boysel, Lee. "Adder on a Chip: LSI Helps Reduce Cost of Small Machine." Electronics (March 18, 1968) pp. 119-123.

Boysel Lee L. & Murphy, Joseph P. "Four-Phase LSI Logic Offers New Approach to Computer Designers," Computer Design (April 1970) pp. 141-146.

Holt, Ray M. “Architecture of a Microprocessor” Accepted for publication in Computer Design (1971 withdrawn for security reasons, released 1998).

Faggin, F. and Hoff, M.E. "Standard parts and custom design merge in four-chip processor kit," Electronics (April 24, 1972) pp. 112-116.

Faggin, F., Shima, M., Hoff, M.E., Feeny, H., Mazor S. "The MCS4 - An LSI micro-computer system," IEEE 1972 Region Six Conference, IEEE Press (1972) pp. 8-11.

Hoff, Jr., M. E., Mazor, Stanley, Faggin, Federico. "Memory System for a Multi-Chip Digital Computer" U. S. Patent 3,821,715 (Filed January 22, 1973. Issued June 28, 1974).

Oral History transcripts online at the Computer History Museum

Faggin, Federico (Fairchild, Intel, Zilog), an oral history (2004-9-22)

Feeney, Hal (Intel), an oral history (2004-6-23)

House, Dave (Honeywell, Intel), an oral history (2004-4-20)

Poor, Vic (CTC, Datapoint), an oral history (2004-12-8)

AMD 2900 Microprocessor oral history panel - Downing, Ghest, Holbrook, McConnell, Mick, Simonsen, Springer (2009-2-11)

Intel 4004 Microprocessor, interview with Ted Hoff & Stan Mazor (2006-9-20)

Intel 4004 Microprocessor oral history panel - Faggin, Feeny, Hoff, Masatoshi, Mazor (2007-4-25)

Intel 8008 Microprocessor oral history panel - Faggin, Feeny, Gelbach, Hoff, Mazor, Smith (2006-9-21)

Intel 8080 Microprocessor oral history panel - Bisset, Faggin, Feeny, Gelbach, Hoff, Mazor, Shima (2007-4-26)

Intel 386 Microprocessor Sole Source Decision oral history panel - Carsten, Dunlap, House, Jenkins (2008-08-14)

Intel 386 Microprocessor Development Team oral history panel - Crawford, Hill, Jarrett, Leukhardt, Prak, Slager (2008-12-02)

Intel 386 Microprocessor Marketing Oral History Panel- Alexy, Krelle, Leglise, Leukhardt, Rey (2008-12-02)

Motorola 6800 Microprocessor oral history panel - Bennett, Ekiss, Lattin, LaVell (2008-3-28)

Motorola 68000 Microprocessor oral history panel - Browne, Goldman, Gunter, Shahan, Walker (2007-7-23)

National 32000 Microprocessor oral history panel - Alpert, Bal, Freund, Sanquini, Yaron (2008-2-26)

Zilog Z80 Microprocessor oral history panel - Faggin, Shima, Ungermann (2007-4-27)

Zilog Z8000 Microprocessor oral history panel - Faggin, Peuto, Shima, Ungermann (2007-4-27)

More Oral Histories

Boone, Gary. An Interview Conducted by David Morton, Center for the History of Electrical Engineering, June 22, 1996, Interview #273 for the Center for the History of Electrical Engineering, The Institute of Electrical and Electronics Engineers, Inc. and Rutgers, The State University of New Jersey.

Faggin, Federico. Electrical Engineer, an oral history conducted in 2004 by John Vardalas, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.

Faggin, Federico (Fairchild and Intel) The Silicon Genesis Interviews (3.3.1995). Department of Special Collections, Stanford University Libraries, Stanford, California.

Hoff, Marcian (Ted) (Intel) The Silicon Genesis Interviews (3.3.1995). Department of Special Collections, Stanford University Libraries, Stanford, California.

Mazor, Stan (Intel) The Silicon Genesis Interviews (6.9.2000). Department of Special Collections, Stanford University Libraries, Stanford, California.

Shima, Masatoshi. Electrical Engineer, an oral history conducted in 1994 by William Aspray, IEEE History Center, Rutgers University, New Brunswick, NJ, USA

More Information

Altman, Laurence "Single Chip Microprocessors open up a New World of Applications," Electronics (April 18, 1974) pp. 81-87

Noyce, R., and Hoff, M. "A History of Microprocessor Development at Intel," IEEE Micro, Vol. 1, No. 1 (1981) pp. 8-21

Augarten, Stan. "The First Microprocessor - 4004," State Of The Art: A Photographic History of the Integrated Circuit. (New Haven & New York: Ticknor and Fields, 1983) pp.30, also see pp. 34, 36, 40, 44, 46, and 48

Malone, Michael S. The Microprocessor: A Biography. (New York: Springer-Verlag TELOS, 1995) pp.10-15

Faggin, F.; Hoff, M.E., Jr.; Mazor, S.; Shima, M. "The history of the 4004," IEEE Micro Vol. 16, Issue 6 (December 1996) pp: 10–20

Aspray, William. "The Intel 4004 Microprocessor: What Constituted Invention?" IEEE Annals of the History of Computing, Vol. 19, No. 3 (July-September 1997) pp. 4-15

Betker, Michael R., Fernando, John S., Whalen, Shaun P. "The History of the Microprocessor," Bell Labs Technical Journal (Autumn 1997) pp. 29-59.

Seitz, Frederick, and Einsprunch. Norman G. Electronic Genie: The Tangled History of Silicon. (Urbana and Chicago, IL: University of Illinois Press, 1998) p. 229.

Mazor, Stanley. "Intel 8080 CPU Chip Development," IEEE Annals of the History of Computing, Vol. 29, No. 2 (Apr-June, 2007) pp. 70-73

Mazor, Stanley. "Intel's 8086" IEEE Annals of the History of Computing, Vol. 32, No. 1 (January 2010) pp. 75-79