SEAC (computer)

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SEAC (Standards Electronic/Eastern Automatic Computer) was a first-generation electronic computer, built in 1950 by the U.S. National Bureau of Standards (NBS) and was initially called the National Bureau of Standards Interim Computer, because it was a small-scale computer designed to be built quickly and put into operation while the NBS waited for more powerful computers to be completed. SEAC was demonstrated in April 1950, and in May 1950 it went into full production, making it the first fully functional stored-program electronic computer in the US.

[edit] Description

Based on EDVAC, SEAC used only 747 vacuum tubes (a small number for the time) eventually expanded to 1500 tubes but 10,500 germanium diodes also expanded to 16,000. It also used no transistors, since all of the logic was done with diodes, making it the first computer to do all of its logic with solid-state devices. The tubes were used only for amplification. The machine used 64 acoustic delay lines to store 512 words of memory, with each word being 45 bits in size. The clock rate was kept low (1 MHz).

The computer's instruction set consisted of only eleven types of instructions: fixed-point addition, subtraction, multiplication, and division; comparison, and input & output eventually expanded to 16. The addition time was 864 microseconds and the multiplication time was 2980 microseconds (i.e. close to 3 milliseconds).

[edit] Applications

On some occasions SEAC was used by a remote teletype. This makes it one of the first computers to be used remotely. With many modifications, it was used until 1964. Some of the problems run on it dealt with:

meteorology
linear programming
optical lenses
a program for Los Alamos National Laboratory
tables for Loran navigation
statistical sampling plans
wave function of the helium atom
designing a proton synchrotron

[edit] See also

SWAC (Standards Western Automatic Computer)

[edit] References

Williams, Michael R. (1997). A History of Computing Technology. IEEE Computer Society.
Metropolis, N; Howlett, J.; Rota, Gian-Carlo (editors) (1980). A History of Computing in the Twentieth Century. Academic Press. (The chapter "Memories of the Bureau of Standards' SEAC", by Ralph J. Slutz.)

Astin,A.V. (1955), "Computer Development (SEAC and DYSEAC) at the National Bureau of Standards, Washington D.C., National Bureau of Standards Circular 551, U.S. Government Printing Office, January 25, 1955