SEAC (computer)
Encyclopedia
SEAC 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.
, SEAC used only 747 vacuum tube
s (a small number for the time) eventually expanded to 1500 tubes. It had 10,500 germanium
diode
s which performed all of the logic functions. They were expanded to 16,000. It was the first computer to do all of its logic with solid-state devices. The tubes were used only for amplification and/or inversion
. The machine used 64 acoustic delay lines
to store 512 words of memory
, with each word being 45 bit
s 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).
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
, built in 1950 by the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
National Bureau of Standards
National Institute of Standards and Technology
The National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...
(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
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...
electronic computer in the US.
Description
Based on EDVACEDVAC
EDVAC was one of the earliest electronic computers. Unlike its predecessor the ENIAC, it was binary rather than decimal, and was a stored program computer....
, SEAC used only 747 vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
s (a small number for the time) eventually expanded to 1500 tubes. It had 10,500 germanium
Germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s which performed all of the logic functions. They were expanded to 16,000. It was the first computer to do all of its logic with solid-state devices. The tubes were used only for amplification and/or inversion
Inverter (logic gate)
In digital logic, an inverter or NOT gate is a logic gate which implements logical negation. The truth table is shown on the right.This represents perfect switching behavior, which is the defining assumption in Digital electronics. In practice, actual devices have electrical characteristics that...
. The machine used 64 acoustic delay lines
Delay line memory
Delay line memory was a form of computer memory used on some of the earliest digital computers. Like many modern forms of electronic computer memory, delay line memory was a refreshable memory, but as opposed to modern random-access memory, delay line memory was serial-access...
to store 512 words of memory
Computer storage
Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers....
, with each word being 45 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s in size. The clock rate
Clock rate
The clock rate typically refers to the frequency that a CPU is running at.For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wave...
was kept low (1 MHz).
The computer's instruction set consisted of only eleven types of instructions: fixed-point
Fixed-point arithmetic
In computing, a fixed-point number representation is a real data type for a number that has a fixed number of digits after the radix 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).
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:- digital imagingDigital imageA digital image is a numeric representation of a two-dimensional image. Depending on whether or not the image resolution is fixed, it may be of vector or raster type...
, led by Russell A. KirschRussell A. KirschRussell A. Kirsch led a team of colleagues in creating America’s first internally programmable computer, the Standards Eastern Automatic Computer , capable of scanning digital images in 1957. SEAC produced a photograph of Kirsch’s three month old son in a mere 176 pixels, measuring 5x5cm... - meteorologyMeteorologyMeteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...
- linear programmingLinear programmingLinear programming is a mathematical method for determining a way to achieve the best outcome in a given mathematical model for some list of requirements represented as linear relationships...
- optical lenses
- a program for Los Alamos National LaboratoryLos Alamos National LaboratoryLos Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
- tables for LORANLORANLORAN is a terrestrial radio navigation system using low frequency radio transmitters in multiple deployment to determine the location and speed of the receiver....
navigation - statistical sampling plans
- wave function of the heliumHeliumHelium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
atom - designing a protonProtonThe proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
synchrotronSynchrotronA synchrotron is a particular type of cyclic particle accelerator in which the magnetic field and the electric field are carefully synchronised with the travelling particle beam. The proton synchrotron was originally conceived by Sir Marcus Oliphant...
External links
- SEAC and the Start of Image Processing at the National Bureau of Standards – At the NIST virtual museum
- Margaret R. Fox Papers, 1935-1976, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....
, University of Minnesota. collection contains reports, including the original report on the ENIAC, UNIVAC, and many early in-house National Bureau of Standards (NBS) activity reports; memoranda on and histories of SEAC, SWAC, and DYSEAC; programming instructions for the UNIVAC, LARC, and MIDAC; patent evaluations and disclosures; system descriptions; speeches and articles written by Margaret Fox's colleagues; and correspondence of Samuel Alexander, Margaret Fox, and Samuel Williams. Boxes 6-8 of the Fox papers contain documents, reports, and analysis of the NBS's SEAC. - http://www.computerhistory.org/timeline/?year=1950