Prof. Dr. Thorsten Jungmann (last updated 2026-10-03)
George Robert Stibitz (1904–1995) was an American researcher at Bell Labs who is internationally recognized as one of the fathers of the modern digital computer. He was born in York, Pennsylvania, received a bachelor’s degree in mathematics from Denison University, a master’s degree in physics from Union College in 1927 and a Ph.D. in mathematical physics from Cornell University in 1930. He worked at Bell Labs from then until 1941. He was known for his work in the 1930s and 1940s on the realization of Boolean logic digital circuits using electromechanical relays as the switching element.
In November 1937 Stibitz completed a relay-based adder that he later dubbed the ‘Model K’, after his kitchen table, on which it was purportedly assembled; it calculated using binary addition. In late 1938 Bell Labs authorized a full research programme with Stibitz at the helm. He led the development of the Complex Number Calculator, which was completed in October 1939 and in routine use from January 1940; it used electromagnetic relay binary circuits for its operations. In September 1940 he used a modified teletype to send commands over telegraph lines to this calculator in New York, the first real-time, remote use of a computing machine. In April 1942 he suggested in a memo that the term ‘digital’ be used in place of ‘pulse’. In 1965 he received the Harry H. Goode Memorial Award together with Zuse.
Two codes are linked to his name. The Stibitz code, also called excess-3 code (German: Stibitz-Code, also Exzess-3-Code), is named after Stibitz, who used it for the decimal digits of his Complex Number Calculator. It is a self-complementary binary-coded decimal (BCD) code in which each decimal digit is represented by four bits as the digit value plus 3. Its advantage is that a decimal number can be nines’ complemented, as needed for subtraction, simply by inverting all bits. Stibitz also described a reflected binary code in a patent application of 1941, granted in 1943, and used it in a binary pulse counting device; the code later became known as the Gray code.
Reference and further reading:
https://en.wikipedia.org/wiki/George_Stibitz
https://en.wikipedia.org/wiki/Excess-3
https://en.wikipedia.org/wiki/Gray_code