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The Atanasoff-Berry Computer In Operation

Name: The Atanasoff-Berry Computer In Operation
Uploaded: 2010-07-13T21:53:33.000Z
Duration: 22 min 27 s

Introduction to the ABC Computer

Overview of the ABC Computer

John Guston introduces Charles Shorb and presents a replica of the Atanasoff-Berry Computer (ABC), built between 1939 and 1942 at Iowa State.

The ABC is noted as the first electronic digital computer and also the first parallel computer, utilizing modular vacuum tube assemblies for arithmetic operations.

Functionality and Storage

The ABC can hold two equations simultaneously on memory drums, using binary digits (bits) for storage; it has a total capacity of 3,000 bits.

Demonstration involves solving two equations with two unknowns: 2x + 4y = 8 and x - 3y = -11.

Data Entry Process

Punch Card System

Data entry into the ABC is done via punch cards, which were standard until the 1970s; whole numbers are used as floating points are not supported.

To denote negative numbers, a zero is typed in place of a blank space.

Conversion to Binary

Decimal numbers entered on punch cards are converted to binary using a conversion drum that represents binary values through pegs touching brushes.

Operational Mechanics

Power Consumption and Synchronization

The machine operates on less than 1,000 watts, comparable to a hair dryer, and connects to standard wall outlets.

A motor keeps memory drums spinning at one revolution per second while synchronizing with power outlet cycles.

Memory Management

The ABC features dynamic memory with capacitors storing voltage for each bit; these need refreshing every second.

A mechanical card reader processes data by completing circuits when brushes pass over holes in punch cards.

Solving Equations

Inputting Equations

The logic within the ABC adds bit patterns from inputted punch cards into its rotating drum memory.

An oscilloscope displays binary representations of numbers processed by the machine during calculations.

Calculation Process

The operator instructively clears one drum after copying data to another for safekeeping before entering new equations.

The speed of computation is limited by input/output times; reading decimal takes about one second per digit.

Understanding the Mechanism of Early Computers

The Odometer-Like Functionality

The output mechanism resembles an odometer, where independent decimal values are subtracted from a memory number. A solenoid activates to increment the digit wheel until the subtraction results in a sign change.

Dials are numbered in alternating directions to facilitate this process, allowing for mechanical reading of values stored in the computer.

Solving Equations with Early Computers

The forward reduction of equations is completed mechanically; for example, solving 10y = 30 yields y = 3. This value is then back-solved into the original equations.

Eliminating variables can be time-consuming, especially with larger numbers. For 15-digit precision, it may take about two minutes to eliminate one variable, which is still more efficient than manual calculations.

Challenges and Innovations

Using y = 3, the second equation allows for solving x. Adding this equation three times results in x = -2, indicating a negative answer.

Prior to advancements like ABC computers, solving large systems (e.g., 10x10 matrices) was impractical due to exponential increases in workload as equations doubled.

Intermediate Storage Solutions

To manage intermediate work efficiently at NASA, Barry invented an electronic recorder capable of storing all bits onto stiff paper using high-voltage arcs that punch holes representing binary data.

Demonstration of Computational Capability

Video description

[Recorded: 1999] The Atanasoff-Berry Computer (ABC) occupies a special place in the history of computing in part for its technical accomplishments but also for being at the center of a landmark legal case. It was built by Iowa physics professor John Vincent Atanasoff and graduate student Clifford Berry. Technically, the ABC was an electronic equation solver. It could find solutions to systems of simultaneous linear equations with up to 29 unknowns, a type of problem encountered in Atansasoff's physics work. Construction of the ABC began in 1938 at Iowa State College (now University) in Ames, Iowa. It was about the size of a large desk, weighed 750 lbs, computed 0.06 operations per second (sustained) and had 0.37 KB of memory. It could also do 30 add/subtract operations per second. While not a computer in the modern sense (since it did not store its own program), it pioneered various techniques in digital computer design including binary arithmetic, parallel processing, and electronic (vacuum tube) switching elements. The device was completed in 1942 and worked, although its spark-gap printer mechanism needed further development. The legal dimension to the ABC story involves a lawsuit between two computer makers, Honeywell and Sperry-Rand. In 1967, Honeywell sued Sperry over their ENIAC patents using the ABC as evidence of prior art. (ENIAC was an early digital electronic calculator completed in 1946). After years of proceedings, on October 19, 1973 the judge in the case, Earl R. Larson, agreed with Honeywell that some of the ideas in the ENIAC, which had been considered the 'world's first computer,' in fact came from Atanasoff during a four-day visit ENIAC designer John Mauchly made to Atanasoff at Iowa State before ENIAC was designed. There was also months of correspondence between the two in which Mauchly expressed his desire to build a similar device. The net result of this judgment was that no one owned the patent on the computer: it was free to be developed by all. Gordon Bell has called this the 'dis-invention of the computer.' In 1993, Iowa State University began a historically-accurate reconstruction of the ABC, which it finished in 1997. The project cost $360,000 and involved about a dozen people in its realization. This film shows the ABC Reconstruction in operation, solving a simple algebra problem. Catalog number: 102781093 Lot number: X6054.2011