This Day in Tech History

On This Day . . .

Prototype of the Modern Computer

EPSON scanner imageMay 31, 1943:  70th Anniversary of Construction of ENIAC Begins

The building of the Electronic Numerical Integrator And Computer (ENIAC) begins at the University of Pennsylvania’s Moore School of Electrical Engineering.

ENIACElectronic Numerical Integrator And Computer) was the first electronic general-purpose computer. It was Turing-complete, digital, and capable of being reprogrammed to solve a full range of computing problems.

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The Army financed the project during World War II, which cost almost $500,000 (approximately $5,900,000 today).  John Mauchly was the chief consultant and John Presper Eckert Jr. (a 24-year-old genius inventor and lab assistant) was the chief engineer.  ENIAC was code named “Project PX”.

Mauchly left Eckert right

Mauchly left Eckert right

This was a modular computer, designed in “panels”.  You could build to suit.  Of course, this machine was so big, it took up whole rooms.  It ran hot, too – using Octal based radio tubes.  ENIAC could be programmed to perform complex sequences of operations, including loops, branches, and subroutines.

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Scholars argue about its claims as the world’s first all electronic computer and the courts have ruled otherwise, but when the University of Pennsylvania’s “mathematical brain” was made public in 1946 it was an incredible breakthrough that could compute mathematical problems with breathtaking speed.

By today’s standards for electronic computers the ENIAC was a grotesque monster. Its thirty separate units, plus power supply and forced-air cooling, weighed over thirty tons. Its 19,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors consumed almost 200 kilowatts of electrical power.

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But ENIAC was the prototype from which most other modern computers evolved. It embodied almost all the components and concepts of today’s high- speed, electronic digital computers.  Its designers conceived what has now become standard circuitry such as the gate (logical “and” element), buffer (logical “or” element) and used a modified Eccles-Jordan flip-flop as a logical, high-speed storage-and-control device. The machine’s counters and accumulators, with more sophisticated innovations, were made up of combinations of these basic elements.

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ENIAC contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed more than 30 short tons (27 t), was roughly 8 by 3 by 100 feet (2.4 m × 0.9 m × 30 m), took up 1800 square feet (167 m2), and consumed 150 kW of power.  This led to the rumor that whenever the computer was switched on, lights in Philadelphia dimmed.  Input was possible from an IBM card reader, and an IBM card punch was used for output.  These cards could be used to produce printed output offline using an IBM accounting machine, such as the IBM 405.

In 1997, the six women who did most of the programming of ENIAC were inducted into the Women in Technology International Hall of Fame.   As they were called by each other in 1946, they were Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman.  Jennifer S. Light’s essay, “When Computers Were Women”, documents and describes the role of the women of ENIAC as well as outlines the historical omission or downplay of women’s roles in computer science history.  The role of the ENIAC programmers was also treated in a 2010 documentary film by LeAnn Erickson.

Kay McNulty, Betty Snyder, Marlyn Wescoff, Ruth Lichterman, Betty Jennings (not pictured), and Fran Bilas (not pictured), original programmers of the ENIAC starting in 1946, WITI Hall of Fame 1997

Kay McNulty, Betty Snyder, Marlyn Wescoff, Ruth Lichterman, Betty Jennings (not pictured), and Fran Bilas (not pictured), original programmers of the ENIAC starting in 1946, WITI Hall of Fame 1997

Today, a single microchip, no bigger than a fingernail, can do more than those 30 tons of hardware.  About 10 percent of the historic computer lives on in the same basement room where it was created.  ENIAC’s 50th anniversary was celebrated in 1996 with a visit by Vice President Al Gore.  What was left of the old computer was fired up one last time.

Piece of ENIAC on display at the University of Pennsylvania

Piece of ENIAC on display at the University of Pennsylvania

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