IBM SSEC

Selective Sequence Electronic CalculatorIBM Selective Sequence Electronic CalculatorSSECearly computing machinesSelective Sequence Electronic Calculator (SSEC)
The IBM Selective Sequence Electronic Calculator (SSEC) was an electromechanical computer built by IBM.wikipedia
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Robert Rex Seeber Jr.

Robert Rex Seeber Jr. was also hired away from the Harvard group, and became known as the chief architect of the new machine.
Robert Rex Seeber Jr. (1910-1969), an inventor at IBM, co-invented the Selective Sequence Electronic Calculator (SSEC).

Stored-program computer

stored programstored-programprogrammable computer
It had many of the features of a stored-program computer and was the first operational machine able to treat its instructions as data, but it was not fully electronic.
It is sometimes claimed that the IBM SSEC, operational in January 1948, was the first stored-program computer; this claim is controversial, not least because of the hierarchical memory system of the SSEC, and because some aspects of its operations, like access to relays or tape drives, were determined by plugging.

Harvard Mark I

Mark IAutomatic Sequence Controlled CalculatorIBM ASCC
The machine, formally dedicated in August 1944, was widely known as the Harvard Mark I.
IBM went on to build its Selective Sequence Electronic Calculator (SSEC) to both test new technology and provide more publicity for the company's own efforts.

Mechanical computer

electromechanical computermechanicalmechanical computers
The IBM Selective Sequence Electronic Calculator (SSEC) was an electromechanical computer built by IBM.

Wallace John Eckert

Wallace EckertWallace J. EckertW J Eckert
Astronomer Wallace John Eckert of Columbia University provided specifications for the new machine; the project budget of almost $1 million was an immense amount for the time.
Known as the Selective Sequence Electronic Calculator, it was used as a calculating device with some success, but served even better as a recruiting tool.

John Backus

John W. BackusBackusBackus, John
Using well-tested technology, the SSEC's calculations were accurate and precise for its time, but one early programmer, John Backus, said "you had to be there the entire time the program was running, because it would stop every three minutes, and only the people who had programmed it could see how to get it running again”. ENIAC co-designer J. Presper Eckert (no relation to the IBM Eckert) called it "some big monstrosity over there that I don't think ever worked right".
During his first three years, he worked on the Selective Sequence Electronic Calculator (SSEC); his first major project was to write a program to calculate positions of the Moon.

IBM 603

603 Electronic Multiplier
The arithmetic logic unit of the SSEC was a modified IBM 603 electronic multiplier, which had been designed by James W. Bryce.
(The earlier IBM 600 and IBM 602 used relay logic.) The IBM 603 was adapted as the arithmetic unit in the IBM Selective Sequence Electronic Calculator.

Robert D. Richtmyer

R. D. RichtmyerRobert Davis RichtmyerRobert Richtmyer
Robert D. Richtmyer of Los Alamos National Laboratory used the SSEC for some of the first large-scale applications of the Monte Carlo method.
Richtmyer used the massive IBM SSEC calculator for some of the first large-scale uses of what would be called the Monte Carlo method.

Cuthbert Hurd

Cuthbert C. HurdHurd, Cuthbert
In 1949, Cuthbert Hurd was hired (also after a visit to the SSEC) and started a department of applied science; the operation of SSEC was eventually put into that organization.
In February 1948 he was invited to the dedication of the IBM Selective Sequence Electronic Calculator (SSEC), a custom-built machine in New York City.

James W. Bryce

The arithmetic logic unit of the SSEC was a modified IBM 603 electronic multiplier, which had been designed by James W. Bryce.
He adapted the 603 to become the arithmetic logic unit in the Selective Sequence Electronic Calculator (SSEC).

History of IBM

IBMIBM Federal Systems Divisionunbundling of software and services
1948: IBM SSEC

Self-modifying code

self-modifyingrun-time code generationRuntime Code Generation
The IBM SSEC, demonstrated in January 1948, had the ability to modify its instructions or otherwise treat them exactly like data.

History of computing hardware

History of computer hardwarehistory of computerscomputer history
In two 1936 patent applications, Zuse also anticipated that machine instructions could be stored in the same storage used for data—the key insight of what became known as the von Neumann architecture, first implemented in 1948 in America in the electromechanical IBM SSEC and in Britain in the fully electronic Manchester Baby.

Von Neumann architecture

von Neumannvon Neumann bottleneckvon Neumann machine
The stored-program concept had been first widely published in 1945 in the First Draft of a Report on the EDVAC and became known as the Von Neumann architecture.

IBM

International Business MachinesIBM CorporationInternational Business Machines Corporation
The IBM Selective Sequence Electronic Calculator (SSEC) was an electromechanical computer built by IBM.

Howard H. Aiken

Howard AikenAiken, HowardHoward Aitken
During World War II, International Business Machines Corporation (IBM) funded and built an Automatic Sequence Controlled Calculator (ASCC) for Howard H. Aiken at Harvard University.

Harvard University

HarvardHarvard CollegeUniversity of Harvard
During World War II, International Business Machines Corporation (IBM) funded and built an Automatic Sequence Controlled Calculator (ASCC) for Howard H. Aiken at Harvard University.

Thomas J. Watson

Thomas J. Watson, Sr.Thomas J. Watson Sr.Thomas Watson
The President of IBM, Thomas J. Watson Sr., did not like Aiken's press release that gave no credit to IBM for its funding and engineering effort.

Columbia University

ColumbiaColumbia CollegeUniversity of Columbia
Astronomer Wallace John Eckert of Columbia University provided specifications for the new machine; the project budget of almost $1 million was an immense amount for the time.

Endicott, New York

EndicottEndicott, NYHenry B. Endicott
Modules were manufactured in IBM's facility at Endicott, New York, under Director of Engineering John McPherson after the basic design was ready in December 1945.

ENIAC

Electronic Numerical Integrator And ComputerElectronic computerENIAC (Electronic Numerical Integrator and Computer)
The February 1946 announcement of the fully electronic ENIAC energized the project.

New York City

New YorkNew York, New YorkNew York City, New York
The SSEC was installed on three sides of a room on the ground floor of a building near IBM's headquarters at 590 Madison Avenue in New York City, behind a large window where it was visible to people passing by on the busy street.

Herb Grosch

Herbert R. J. GroschHerbert R.J. GroschHerbert Reuben John Grosch
Herb Grosch, the second person with a Ph.D. hired by IBM, was one of its first programmers.

Edgar F. Codd

E. F. CoddE.F. CoddCodd
Another early programmer was Edgar "Ted" Codd.

Vacuum tube

vacuum tubestubethermionic valve
The SSEC was an unusual hybrid of vacuum tubes and electromechanical relays.