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The Atanasoff - Berry - Computer
at the Computer History Museum
as of March 19, 2011
The reconstructed Atanasoff - Berry - Computer is on loan to the Computer History Museum,
Mountain View, California.
It is displayed in the new (2011) formally presented (world class) display
of artifacts called
R|EVOLUTION.
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The ABC is the first known device to use vacuum tubes for digital arithmetic work.
Here is a display to the left of the ABC of a standardized arithmetic chassis using 7 vacuum tubes.
To ease quick replacement
in case of suspected trouble, the plug at the bottom contained all of the logical
and power connections to the unit.
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First a little orientation -
ABC at CHM
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courtesy
Alice R. Burks.
| This is an annotated drawing from Burks & Burks.
Another view of the machine (in Iowa) is
here
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Views of the left, front, right. The rear
is mostly obscured by a wall of the display area.
Views of the left
| Left side
| The two big drums, Keyboard & Counter, store 1500 bits each.
Each drum stores 30 binary numbers of 50 bits each.
| Conversion Drum. These brushes, electrically contacting the metal Conversion Drum, assist in
converting the holes in the IBM card reader into binary for computation in the
ABC.
| More arithmetic chassis center, right is high voltage electronics
to blast holes in the paper for intermediate result output.
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Views of the front
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The intermediate result "punch" and reader. The coin is a quarter for size reference.
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This unit reads IBM cards, 5 numeric fields/card, into the ABC via the Decode drum.
The yellow arrow points to the ABC output device, a ratcheting counter for the
operator to read.
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The operator reads this "odometer" to obtain the decimal value of the variable just computed.
Note the ratcheting operated from the solenoid, and that the numbers go in different directions.
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Views of the right
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This synchronous motor drives all the mechanical systems in the ABC.
It is synchronous so that the Positive cycle of the wall power sine wave
is at the correct mechanical point for hole blasting for intermediate output.
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Motor tag - 1/4 horsepower, 1800 RPM - exactly one revolution each two cycles of
AC power.
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Right side view
- Motor left middle
- Shaft hidden in middle horizontal L-bracket
- Visible gear goes 1 revolution per second, provides
timing for whole machine
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If you have comments or suggestions, Send e-mail
to Ed Thelen
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