In November 1937, George Stibitz, then working at Bell Labs(1930-1941),
completed a relay-based calculator he later dubbed the"Model K"(for"kitchen table", on which he had assembled it), which calculated using binary addition.
In a demonstration to the American Mathematical Society
conference at Dartmouth College in September 1940, Stibitz used a modified teletype to send commands
to the Complex Number Computer in New York over telegraph lines.
While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the“Model K”(for“kitchen table”,
on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation.