Computer History MuseumSemiconductor History

1974 - General-Purpose Microcontroller Family is Announced

A single-chip calculator design emerges as the TMS 1000 micro-control unit or MCU, a concept that spawned families of general-purpose digital workhorses that power the tools and toys of the developed world.

A microcontroller unit (MCU) comprises the same basic ROM, RAM and CPU elements as a microprocessor (MPU) for less demanding tasks such as controlling a toy or a microwave oven. As these applications do not require the ultimate in speed or program complexity, MCU designs can be implemented with fewer components so that the complete function will fit on a single chip.

Gary Boone and Michael Cochran's 1971 design of Texas Instruments TMS1802 single-chip calculator device provided the foundation for the TMS1000 general-purpose 4-bit MCU family announced in 1974. Priced at $2 in volume, it powered burglar alarms, garage door openers, games, and toys such as "Speak and Spell" that introduced digital electronics to the consumer.

In 1976 both Intel and Mostek (3870) introduced 8-bit architectures that served more demanding applications in automobiles and PC peripherals. The Intel MCS-48 family offered both EPROM (8748) and masked-ROM (8048) versions. The EPROM version made MCUs practical for prototyping and low-volume production systems. (1971 Milestone) Intel's more powerful 1980 successor, the 8051, established a standard architecture that survives today in numerous variants for specific applications.

By the 1980s MCU architectures from European, Japanese and US manufacturers served numerous special-purpose applications. Bell Laboratories' MAC-4 met telecommunications needs. Motorola and Hitachi derived high-performance MCUs from the 68000 MPU. General Instrument's PIC family (today Microchip) won low-cost consumer designs. Hidden by the hundreds in appliances, automobiles, and personal electronics products, the MCU may be today's most ubiquitous semiconductor device.



Contemporary Documents

Boone, Gary W. "Computing Systems CPU" U. S. Patent 3,757,306 (Filed August 31, 1971. Issued September 4, 1973).

Blume, H., Budde, D., Raphael, H. & Stamm, D. "Single-Chip 8-Bit Microcomputer Fills Gap between Calculator Types and Powerful Multichip Processors," Electronics (November 25, 1976) pp. 99-105.

Boone, Gary W. and Cochran, Michael J. "Variable function programmed calculator" U. S. Patent 4,074,351 (Filed February 24, 1977. Issued February 14, 1978).

Eldumiati, I.I., Huang, V.K.L., Kirby, D.B., Shichman, H., Stanzione, D.C., Townsend, R.L., Ukeiley, R.L. "MAC-4: A Single-Chip Microcomputer," Compcon Fall 79, Proceedings (September 4-7, 1979) pp. 13-17.

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.

More Information

Augarten, Stan. "The Most Widely Used Computer on a Chip," State Of The Art: A Photographic History of the Integrated Circuit. (New Haven & New York: Ticknor and Fields, 1983) p. 38.

Malone, Michael S. The Microprocessor: A Biography. (New York: Springer-Verlag TELOS, 1995) p. 132.

Nunnally, C.E. "Teaching Microcontrollers," Frontiers in Education Conference, 1996. FIE '96. Proceedings of 26th Annual Conference, Vol. 1 (November 6-9, 1996) pp. 434-436.

Seitz, Frederick, and Einsprunch. Norman G. "1970s and the Microcontroller" Chapter 19 of Electronic Genie: The Tangled History of Silicon. (Urbana and Chicago, IL: University of Illinois Press, 1998) p. 229.