© Mark Ollig
April 9, 1943, the Electronic Numerical Integrator and Computer, better known as ENIAC, began under the secret code name “Project PX.”
Its design and construction were financed by the US Army during World War II to assist with the war effort against Germany’s armed forces.
The ENIAC was a highly-advanced electronic digital computational computer developed at the University of Pennsylvania’s Moore School of Electrical Engineering.
The principal consultant for Project PX was physicist Dr. John William Mauchly, who pronounced the name of the ENIAC as “EN-ee-ack,” unlike the standard pronunciation at the time of “EEN-ee-ack.”
Mauchly, 38, and his chief engineer, John Presper Eckert Jr., 26, built the ENIAC.
Eckert engineered the project and solved many of its technical problems, including how to get better dependability from the 10 different types of vacuum tubes by operating some at one-quarter of their standard power rating.
Mauchly worked with the hardware and electrical component configurations.
Arithmetic, memory, and control elements were part of ENIAC’s operating system.
The computer used 20 processing registers, or “accumulators,” for addition, subtraction, multiplication, division, and square-root problem-solving.
Sub-elements of the ENIAC were binary, and its processing clock speed was 100 kHz per second.
The ENIAC computer weighed 30 tons and was U-shaped. Its 40-panel bays, some 9 feet high, filled a 30-foot-by-50-foot room.
Commercial power fed directly into the computer’s primary power input sources. ENIAC required 174 kilowatts of power to operate.
The computer used approximately 70,000 resisters, 10,000 capacitors, 18,000 vacuum tubes, and miles of wire, including 5 million hand-soldered joints to connect all the electrical components and wiring.
Two 20-horsepower fans blew cold air onto the vacuum tubes, resistors, and other components from overhead circular and rectangular sheet metal vents to prevent them from overheating.
The computer’s programming interface used 3,000 rotary switches and dozens of front patching cables plugged into sockets on the central control operating panels.
Programming the computer took place by adjusting switches and physically plugging cross-connect cables into the correct sockets to work the desired computations.
Different computations required the patch cords to be re-plugged into the correct computing registers, and the control switch positions needed to be changed.
When I saw a photo of the ENIAC’s cords patched into its main control panel, it reminded me of an old-style telephone operator switchboard.
During 1945, the Army used the ENIAC’s computing power to solve military ballistic equations and artillery firing control problems.
At the time, ballistic targeting calculations usually took 12 hours to perform, using a mechanical calculator. The ENIAC could perform these calculations in just 30 seconds.
Other uses for the computer’s processing capabilities included weather forecasting, wind-tunnel designs, atomic-energy calculations, and various scientific applications.
Maintaining a 24-hour-a-day operation of the computer required six technicians working three eight-hour shifts, seven days a week.
The six original programmers of the ENIAC were: Betty Snyder Holberton, Jean Jennings Bartik, Kathleen McNulty, Marlyn Wescoff Meltzer, Ruth Lichterman Teitelbaum, and Frances Bilas Spence.
It’s important to note these six computing pioneers created some of the basic concepts used in modern computer programming, including subroutines and nested loops.
Calculations could be entered into ENIAC using IBM punch cards. After computing the solution, it would print the results on other punch cards, which would be fed and read through a punch card reader.
The ENIAC had no built-in electronic component arrangement to store memory, and so again, punch cards held the data.
It must have been an opportune time to have stock in companies producing punch cards.
In November 1945, the ENIAC was fully completed – two months after World War II.
The ENIAC’s final cost was $487,000, which today would equal a little over $7 million.
The computer’s existence was kept secret by the US government until 1946.
The Minneapolis Morning Tribune, dated Friday, Feb. 15, 1946, had a front-page story announcing ENIAC to the folks living in Minnesota.
“30-Ton Robot Figures Everything But Cost” was written by Minneapolis Tribune staff correspondent Martin Took.
A front-page photo of the ENIAC included Mauchly, Eckert, and some of the women programmers. The caption read: “ENIAC, the army’s electronic robot calculator.”
The article revealed how the computer performed and solved a single addition problem in 1/5,000 of a second, and how it completed “many distinct additions simultaneously.”
June 24, 1947, the US Patent Office granted John Mauchly and John Eckert Jr. patent number 3,120,606 for “Electronic Numerical Integrator And Computer.”
On this day, 65 years ago, at 11:45 p.m., ENIAC, the first large-scale, fully electronic digital computer, was turned off.
Four of ENIAC’s original front computing panels are on display at the University of Pennsylvania School of Engineering and Applied Sciences.
Stay safe out there.
