comparative display of relays for Harvard Mark I-IV computers
Date: 1944-1952
Inventory Number: 1997-1-0244
Classification: Computer Part
Subject:
Maker: Harvard Computation Laboratory (1944 - 1997)
Maker: International Business Machines Corporation (1911-present)
Maker: Howard H. Aiken (1900 - 1973)
Maker: Benjamin M. Durfee (1897 - 1980)
Maker: Clair D. Lake (1888 - 1958)
Maker: Frank E. Hamilton (1898 - 1972)
Associate Name: Grace Murray Hopper (1906 - 1992)
User: United States Navy (founded 1775)
Maker: Harvard Computation Laboratory (1944 - 1997)
Cultural Region:
Place of Origin:
Dimensions:
7.5 × 28.5 × 14.5 cm (2 15/16 × 11 1/4 × 5 11/16 in.)
Description:
Black plastic base with four relays mounted on it. The typed paper label above the relays reads:
MARK 1
Coil Res #1 1480 Ohms
Coil Res #2 1500 Ohms
Contact Pressure 30 grams
P.U. 12.6 ms. D.O. 9.2 ms.
MARK 2
Coil Res 4 in series 2400
Contact Pressure 30 Grams
P.U. 8.6 ms. D.O. 5.3 ms.
MARK 3
Coil Res 2200 Ohms
Contact Pressure 30 grams
P.U. 6.5 ms. D.O. 5.3 ms.
MARK 4
Coil Res 1620 Ohms
Contact Pressure 30 grams
P.U. 5.0 ms. D.O. 4.7 ms.
MARK 1
Coil Res #1 1480 Ohms
Coil Res #2 1500 Ohms
Contact Pressure 30 grams
P.U. 12.6 ms. D.O. 9.2 ms.
MARK 2
Coil Res 4 in series 2400
Contact Pressure 30 Grams
P.U. 8.6 ms. D.O. 5.3 ms.
MARK 3
Coil Res 2200 Ohms
Contact Pressure 30 grams
P.U. 6.5 ms. D.O. 5.3 ms.
MARK 4
Coil Res 1620 Ohms
Contact Pressure 30 grams
P.U. 5.0 ms. D.O. 4.7 ms.
Signedunsigned
FunctionRelays, as electrical switches, were among the primary logical elements of the early computers.
Historical AttributesThis display came from the Aiken Computation Laboratory at Harvard and shows the evolution of relays on the Harvard Mark I, Mark II, Mark III, and Mark IV computers.
The Harvard Mark I computer--the IBM Automatic Sequence Controlled Calculator (ASCC)--was an electromechanical computer completed in 1944. It was designed and built by Howard Aiken, Clair D. Lake, Benjamin Durfee, and Frank Hamilton.
The Harvard Mark II computer was another electromechanical computer. It was also designed by Aiken for the U. S. Navy. It became operational in 1947 and was delivered to the U. S. Navy Proving Ground at Dahlgren, Virginia. Grace Murray Hopper worked on this computer, and was the one who found a moth stuck in a relay.
The Harvard Mark III computer--also known as the Aiken Dahlgren Electronic Calculator (ADEC)--was an electronic computer built at Harvard under the supervision of Aiken. The Mark III's word consisted of thirty-six bits, storing sixteen decimal digits, plus a sign. It used 5,000 vacuum tubes and 1,500 crystal diodes. It used magnetic drum memory of 4,350 words. The Mark III was finished in September 1949 and delivered to the U.S. Navy Proving Ground at Dahlgren, Virginia in March 1950.
The Harvard Mark IV computer was an electronic stored-program computer built by Harvard University under the supervision of Howard Aiken for the United States Air Force. It was completed in 1952, and remained at Harvard where the Air Force was able to use it. It was one of the first computers to use ferrite magnetic core memory.
The Harvard Mark I computer--the IBM Automatic Sequence Controlled Calculator (ASCC)--was an electromechanical computer completed in 1944. It was designed and built by Howard Aiken, Clair D. Lake, Benjamin Durfee, and Frank Hamilton.
The Harvard Mark II computer was another electromechanical computer. It was also designed by Aiken for the U. S. Navy. It became operational in 1947 and was delivered to the U. S. Navy Proving Ground at Dahlgren, Virginia. Grace Murray Hopper worked on this computer, and was the one who found a moth stuck in a relay.
The Harvard Mark III computer--also known as the Aiken Dahlgren Electronic Calculator (ADEC)--was an electronic computer built at Harvard under the supervision of Aiken. The Mark III's word consisted of thirty-six bits, storing sixteen decimal digits, plus a sign. It used 5,000 vacuum tubes and 1,500 crystal diodes. It used magnetic drum memory of 4,350 words. The Mark III was finished in September 1949 and delivered to the U.S. Navy Proving Ground at Dahlgren, Virginia in March 1950.
The Harvard Mark IV computer was an electronic stored-program computer built by Harvard University under the supervision of Howard Aiken for the United States Air Force. It was completed in 1952, and remained at Harvard where the Air Force was able to use it. It was one of the first computers to use ferrite magnetic core memory.
ProvenanceOn March 13, 1997, it was picked up from the Howard H. Aiken Computation Laboratory, 33 Oxford Street. The instruments were transferred to the Collection by Edward P. Jackson, Facilities Manager in the Division of Engineering and Applied Sciences. Aiken Laboratory is to be destroyed during the summer of 1997 to make way for the new computing building. The instruments would have been disposed of if CHSI had not taken them. Was formerly on exhibition in the entrance area adjacent to the IBM Mark I Computer on the first floor of the Science Centre, Harvard University.