Computer History MuseumSemiconductor History

1953 - Transistorized Computers Emerge

A transistorized computer prototype demonstrates the small size and low-power advantages of semiconductors compared to vacuum tubes.

During the 1950s, semiconductor devices gradually replaced vacuum tubes in digital computers. By 1960 new designs were fully transistorized. Operational in April 1950, the National Bureau of Standards Eastern Automatic Computer (SEAC) employed 10,500 germanium diodes and 747 vacuum tubes.

Working under Tom Kilburn at Manchester University, Richard Grimsdale and Douglas Webb, demonstrated a prototype transistorized computer on November 16, 1953. The 48-bit machine used 92 point-contact transistors and 550 diodes fabricated by STC, the UK arm of ITT. An enhanced version with 250 junction transistors was completed in 1955. The Metropolitan Vickers Electrical Company manufactured six units as the Metrovick 950, which they used commercially within the company from 1956.

Jean H. Felker led a Bell Labs team including engineer James R. Harris that designed and built a fully transistorized computer dubbed TRADIC (TRAnsistor DIgital Computer) for the U. S. Air Force in 1954. Involving about 700 point-contact transistors and over 10,000 diodes, the prototype operated at 1 MHz while requiring less than 100 watts of power. A lighter airborne version (Flyable TRADIC) using junction transistors replaced an analog computer for navigation and bombing control in a C-131 aircraft. Led by William Papian, in April 1956 members of the Advanced Development Group of MIT Lincoln Labs used fast germanium switching transistors from Philco Corporation to build a 5 MHz general-purpose digital computer known as TX-0 (Transistor Experimental). Also in 1956, Japan’s first transistorized computer, the ETL Mark III, using 130 point-contact transistors and 1800 diodes was built under the direction of Hiroshi Wada at the Electrotechnical Laboratory in Tokyo.

Contemporary Documents

Felker, Jean H. "Regenerative Transistor Amplifier," U. S. Patent No. 2,670,445 (Filed 6 November 1951, issued 23 February 1954).

Felker, J. H. "Regenerative Amplifier for Digital Computer Applications," Proceedings of the Institute of Radio Engineers (November 1952) pp. 1584–1596.

Harris, J. R. "A Transistor Shift Register and Serial Adder," Proceedings of the Institute of Radio Engineers (November 1952), pp. 1597–1602.

Kilburn, T., R. L. Grimsdale, and D. C. Webb. "A Transistor Digital Computer with a Magnetic-drum Store," Proceedings of the IEEE Convention on Digital Computer Techniques Vol. 103, Part B (1956).

Harris, J. R. "TRADIC: The First Phase," Bell Laboratories Record (September 1958), pp. 330-334.

RCA 501 Electronic Data Processing System. Promotional brochure, RCA Corporation. (1958).

Philco TRANSAC S-2000: World's fastest all-transistor data processing system. Promotional brochure, Philco Corporation. (1958).

More Information

McKenzie, John A. "TX-O Computer History," RLE Technical Report No. 627 Massachusetts Institute of Technology (October 1, 1974).

Takahasi, Sigeru. "Early Transistor Computers in Japan," Annals of the History of Computing Vol. 8, No. 2 (April 1986) pp. 144-153.

Enticknap, Nicholas ed. "Early computers at Manchester University: Transistor Computer," Computer RESURRECTION: The Bulletin of the Computer Conservation Society Vol. 1, No. 4 (Summer 1992).

Logue, Joseph C. "From Vacuum Tubes to Very Large Scale Integration: A Personal Memoir," IEEE Annals of the History of Computing, Vol. 20, No. 3, (1998) p. 61.

Harris, James R. "The Earliest Solid-State Digital Computers," Annals of the History of Computing, Vol. 21, No. 4 (October-December 1999) pp. 49–54.

Brown, Louis C. "Flyable TRADIC: The First Airborne Transistorized Digital Computer," Annals of the History of Computing, Vol. 21, No. 4 (October-December 1999), pp. 55–61.