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Unisys History NewsletterVolume 3, Number 4
Sperry Rand Military Computers 1957-1975by George Gray
Although many of the computers of the 1940s were developed as military projects, the use of vacuum tubes made them too big and unreliable for incorporation into actual weapons systems. The Eckert-Mauchly Computer Corporation built the BINAC in 1949 for Northrop Aircraft, but no one seriously expected it to be put into an airplane. The massive SAGE (semi-automatic ground environment) system built by IBM during the 1950s for the North American air defense system was for command and control, not for missile guidance. When vacuum tubes were replaced by transistors, it became possible to have computers of smaller size and greater reliability. The transistor was invented at Bell Laboratories in 1948, but it took several years of development to become suitable for use in computers. Bell Labs built the first transistor computer, the TRADIC (Transistor Digital Computer), for the Air Force in 1954. It used 700 point-contact transistors and 10,000 germanium diodes. (A diode is an electronic device which allows current to flow in only one direction.) Both of the two major computer development groups (St. Paul and Philadelphia) at Sperry Rand became involved in early transistor computer projects. Philadelphia became embroiled in the long and costly LARC supercomputer project for the Atomic Energy Commission. St. Paul, building on its early work for the Navy, became heavily involved in military projects.
was core memory unit that I, Mark DiVecchio, tried to add to the Athena. It was my
senior project. It never worked. The core, IIRC, was from the
Bogart. Photo taken about 1971. I am somewhat amazed that this
project sat, virtually untouched, from spring of 1970 until I took this
photo and it probably remained untouched until
Glenn Sembroski diassembled the Athena to ship to the Smithsonian.
From the Bogart Programmers Manual:
1. Core Storage
× This storage can retain 4096 24-bit words, a total of 98,304 bits of information
× The Magnetic-core storage contains 24 planes. Each 10 inch plane is a 64 by 64 square array of 406 cores. Three of the four wires running through each core write information into the core and the fourth wire senses whether a 1 or a 0 is stored in the core.
× If the core is magnetized in one direction, a 1 is stored in it; and if it is magnetized in the reverse direction, a 0 is stored in it. Information read out by applying a current to the two read-out wires drives the core into its zero state. If a 1 is stored in the core, the magnetic direction-change induces a voltage in the read-out wire. By sensing the voltage on the read-out wire, it is possible to determine the previous magnetic state of the core.
× Since the read-out wire sets the core to the zero state, it is necessary for the memory circuits to restore the core to a one-state. If it contains a 1, this is the regeneration portion of the storage cycle. The total storage cycle of read-out and information regeneration takes 20 microseconds per word.
|Photo from the
Bogart Programmers Manual.
The computer was supposedly named after John B. Bogart, city editor of
The (New York) Sun. This was a reference to the Bogart's primary
function - "data editing", what is now called data mining.
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