ENIAC

The First Modern Computer

On February 1, 1946, in Philadelphia, Pennsylvania, ENIAC (Electronic Numerical Integrator and Computer) was unveiled. It was the world's first operational, general purpose, electronic, digital computer. It was developed at the Moore School of Electrical Engineering of the University of Pennsylvania from 1943 - 1945 by a team led by Dr. John W. Mauchly and J. Presper Eckert, Jr., under the direction of the U.S. Army. This achievement literally made possible an entirely new era of amazing scientific accomplishments.

The stimulus which began the effort that produced the ENIAC was provided by the demands of war. One of the extraordinarily important tasks was the preparation of firing and bombing tables for the Army. This job was carried out at the Ballistic Research Laboratory of the Ordnance Department at Aberdeen, Maryland.

Normal desk calculators were the main device used for these calculations, plus one other very important device - the Bush differential analyzer. these machines sped up the task tremendously, but the process was still agonizingly slow. The Moore School of Electrical Engineering of the University of Pennsylvania had a Bush differential analyzer that was much larger than the one at Aberdeen, so the Army contracted with the University of Pennsylvania for its use. An electronic torque amplifier was also to replace the mechanical ones in the Bush differential analyzer.

In the fall of 1942, Mauchly wrote a paper, along with Eckert, developing his idea of an electronic computer. This put forth the idea that higher speeds could be achieved electronically rather than with mechanical devices, and demonstrated the technical concepts underlying the development of the ENIAC.

The primary aim of the designers was to achieve speed by making ENIAC rely on electronics rather than mechanical relays. They also set out to make the electronics simple and reliable. To understand the difficulty of the task, try to realize that the proposed machine turned out to contain over 18,000 tubes. With a signal to each of those tubes every 10 microseconds, this means that there were over 2 billion chances of an error occuring every second.

And what results did the Army get for figuring the trajectory of weapons for those firing and bombong tables that began all this? A skilled person with a desk calculator took about 20 hours to devise a 60 second trajectory. With the Bush differential analyzer, it could be done in about 15 minutes. But with the ENIAC, the same result required only 30 seconds. Which was, of course, less time than the flight actually took. The war was sover before the machine was operational, but the computer was a stunning success.

By today's standards, ENIAC was primitive, a huge monster with its 19,000 vacuum tubes and other assorted hardware. It had thirty separate units, 1,500 relays, 70,000 resistors, 10,000 capacitors, and used nearly 150 kilowatts of electricity. It measured 100 feet long, 10 feet high, and was 3 feet deep. But ENIAC was a great leap forward, its electronic design encompassing nearly everything used today, and it is the prototype from which other computers have evolved.