Harvard Mark IV memory register, word "111"
Date: 1949-1950
Inventory Number: 2007-1-0063
Classification: Computer Memory
Subject:
Maker: Harvard Computation Laboratory (1944 - 1997)
Maker: Howard H. Aiken (1900 - 1973)
Maker: Sylvania Electric Products, Inc. (1924-present)
Maker: General Electric Company (1892-present)
User: United States Air Force (1947-present)
Owner: Albert L. Hopkins (fl. 1930 - 2001)
Owner: Hugh Blair-Smith (A.B. 1957)
Cultural Region:
Place of Origin:
Dimensions:
12 × 74 × 12 cm (4 3/4 × 29 1/8 × 4 3/4 in.)
box: 14 × 77.8 × 14 cm (5 1/2 × 30 5/8 × 5 1/2 in.)
DescriptionThis is a ferrite magnetic core memory register from the Mark IV computer. This register holds "one word" of high speed, random access memory. This is word "111." Each word consists of 16 decimal digits and a ternary sign (+, -, serial). (This is equivalent to about 65-66 bits.)
The memory register is divided into four long stacks that connect with four vacuum tubes. Each plane of four equals one decimal digit. Two planes are required to register each digit as the signal travels from one plane to the next, switching the ferrite core to the opposite state.
The Mark IV was one of the first computers to use ferrite magnetic core memory registers. It had 220 registers. Each one held "one word" of high speed data memory. One instruction was 20 bits read off the drum. The drum storage held 10,000 words. Information was transferred in blocks.
The Sylvania vacuum tubes are twin triodes, 6V6 / GT. They are marked with installation dates of March 26, 1949, and January 6, 1950.
The memory register is divided into four long stacks that connect with four vacuum tubes. Each plane of four equals one decimal digit. Two planes are required to register each digit as the signal travels from one plane to the next, switching the ferrite core to the opposite state.
The Mark IV was one of the first computers to use ferrite magnetic core memory registers. It had 220 registers. Each one held "one word" of high speed data memory. One instruction was 20 bits read off the drum. The drum storage held 10,000 words. Information was transferred in blocks.
The Sylvania vacuum tubes are twin triodes, 6V6 / GT. They are marked with installation dates of March 26, 1949, and January 6, 1950.
In Collection(s)
Signedon 3 vacuum tubes: GE
on 1 vacuum tube: Sylvania
on 1 vacuum tube: Sylvania
Inscribedon end panel, lower left: 111
on end panel, lower right: 3
in paint on end of vacuum tube: 1-6
in paint on end of vacuum tube: 3/26/9
printed on vacuum tubes: 6V6 / GT
on end panel, lower right: 3
in paint on end of vacuum tube: 1-6
in paint on end of vacuum tube: 3/26/9
printed on vacuum tubes: 6V6 / GT
Historical AttributesThe 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.
This particular memory register, word 111, has had a distinguished set of owners. It was owned first by computer scientist, Albert L. Hopkins, who had worked on the Mark IV computer, before becoming Assistant Director of the MIT Instrumentation Laboratory (now known as the Draper Lab) during the development of the Apollo Guidance, Navigation, and Control System.
One of Hopkins's significant projects was the design of the Apollo Guidance Computer (AGC)--an on-board digital computer installed in each Apollo program spacecraft (i.e., in both the Command Module and the Lunar Module). It provided onboard computation to support spacecraft guidance, navigation, and control.
Hopkins's team included software engineer, Hugh Blair-Smith (Harvard AB 1957). As an undergraduate, Blair-Smith worked under Howard Aiken's supervision at the Harvard Computation Laboratory. He continued there after graduation. In 1959, Blair-Smith was recruited from the Harvard Computation Laboratory to the MIT Instrumentation Lab along with Albert Hopkins, Ramon Alonso, and Robert Scott. At the MIT Instrumentation Lab, Blair-Smith designed and developed the assembler for what was to become the Mars mod 1 and its successors mod 2, mod 3C, and the Apollo Gudiance Computer. He also designed and microprogrammed the instruction sets for Mars mod 3C (redesignated AGC3), AGC4 (redesignated AGC Block I), and AGC Block II. He continued to work in this area through a pioneering microprocessor and a Strapdown Inertial Reference Unit control computer, and then on fault-tolerance software for the Space Shuttle program.
In 1982, Blair-Smith left the Lab and was given this memory register as a parting gift from his boss, Albert Hopkins.
This particular memory register, word 111, has had a distinguished set of owners. It was owned first by computer scientist, Albert L. Hopkins, who had worked on the Mark IV computer, before becoming Assistant Director of the MIT Instrumentation Laboratory (now known as the Draper Lab) during the development of the Apollo Guidance, Navigation, and Control System.
One of Hopkins's significant projects was the design of the Apollo Guidance Computer (AGC)--an on-board digital computer installed in each Apollo program spacecraft (i.e., in both the Command Module and the Lunar Module). It provided onboard computation to support spacecraft guidance, navigation, and control.
Hopkins's team included software engineer, Hugh Blair-Smith (Harvard AB 1957). As an undergraduate, Blair-Smith worked under Howard Aiken's supervision at the Harvard Computation Laboratory. He continued there after graduation. In 1959, Blair-Smith was recruited from the Harvard Computation Laboratory to the MIT Instrumentation Lab along with Albert Hopkins, Ramon Alonso, and Robert Scott. At the MIT Instrumentation Lab, Blair-Smith designed and developed the assembler for what was to become the Mars mod 1 and its successors mod 2, mod 3C, and the Apollo Gudiance Computer. He also designed and microprogrammed the instruction sets for Mars mod 3C (redesignated AGC3), AGC4 (redesignated AGC Block I), and AGC Block II. He continued to work in this area through a pioneering microprocessor and a Strapdown Inertial Reference Unit control computer, and then on fault-tolerance software for the Space Shuttle program.
In 1982, Blair-Smith left the Lab and was given this memory register as a parting gift from his boss, Albert Hopkins.
ProvenanceAlbert L. Hopkins, Harvard Computation Laboratory, and from 1959, the MIT Instrumentation Laboratory, owner of this memory register until 1982; Hugh Blair-Smith (AB 1957), Harvard Computation Laboratory, and from 1959-1982, the MIT Instrumentation Laboratory, received register in 1982; gift to CHSI, 2007.