EDVAC

ENIAC inventors, John Mauchly and J. Presper Eckert, proposed the EDVAC's construction in August 1945.

The design would implement a number of important architectural and logical improvements conceived during the ENIAC's construction and would incorporate a high-speed serial-access memory.

[3] Like the ENIAC, the EDVAC was built for the U.S. Army's Ballistics Research Laboratory at the Aberdeen Proving Ground by the University of Pennsylvania's Moore School of Electrical Engineering.

[2]: 626–628  Eckert and Mauchly and the other ENIAC designers were joined by John von Neumann in a consulting role; von Neumann summarized and discussed logical design developments in the 1945 First Draft of a Report on the EDVAC, written between February and June of that year.

Simultaneously, the duo founded the Electronic Control Company (later renamed the Eckert-Mauchly Computer Corporation) in Philadelphia.

[8] The EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory[3] capacity of 1,024 44-bit words, thus giving a memory, in modern terms, of 5.6 kilobytes.

For executable instructions, the 44-bit word was divided into four 10-bit addresses and four bits to encode the index of an operation.

After a number of problems had been discovered and solved, the computer began operation in 1951 although only on a limited basis.

EDVAC received a number of upgrades including punch-card I/O in 1954, extra memory in slower magnetic drum form in 1955, and a floating-point arithmetic unit in 1958.