The History of ENIAC

Transcription

1 The History of ENIAC Thomas McCaffery University of Pennsylvania Thomas McCaffery Bicsi Northeast Regional Meeting March 8, 2012 University of Pennsylvania

2 About Penn Founded in 1740 by Benjamin Franklin. Largest private employer in the city of Philadelphia and the second-largest in the Commonwealth of Pennsylvania. 3 Campus Locations: West Philadelphia campus: 279 acres, 181 buildings (excluding hospital) New Bolton Center: 600 acres, 106 buildings Morris Arboretum: 92 acres, 33 buildings

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4 Start of the Computer Revolution An amazing machine which applies electronic speeds for the first time to mathematical tasks hitherto too difficult and cumbersome for solution. --The New York Times (YEAR)

5 ENIAC: The first general-purpose electronic computer Originally announced on February 14, 1946, the Electronic Numerical Integrator and Computer (ENIAC), was the first general-purpose electronic computer. Developed by John Mauchly and John Presper Eckert. Constructed and operated at Penn s Moore School of Electrical Engineering, now part of the School of Engineering and Applied Science. Mauchly and Eckert, Life Magazine, 1963.

6 ENIAC: Military Origins Commissioned by the Ballistics Research Laboratory in 1943 to calculate new firing tables for guns. Based on Mauchly s work on several calculating machines, some with small electric motors inside. He had begun designing (1942) a better calculating machine based on the work of John Atanasoff that would use vacuum tubes to speed up calculations. Each firing table had trajectories. A person with a desk calculator could computer one trajectory in about 12 hours. When completed, the ENIAC could do the same problem in just 30 seconds-- 1,440 times faster than a person with a calculator! Excerpt from 1941 Firing Table

7 ENIAC: What Was Inside? The ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors, 10,000 capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered joints. It covered 1800 square feet (167 square meters) of floor space, weighed 30 tons, consumed 160 kilowatts of electrical power. There was even a rumor that when turned on the ENIAC caused the city of Philadelphia to experience brownouts. However, this was first reported incorrectly by the Philadelphia Bulletin in 1946 and since then has become an urban myth.

8 ENIAC: How Did It Work? The ENIAC was a modular computer, composed of individual panels to perform different functions. Twenty modules were accumulators, which could add and subtract but hold a ten-digit decimal number in memory. Numbers were passed between these units across a number of general-purpose buses, or trays. To achieve its high speed, panels had to send and receive numbers, compute, save the answer, and trigger the next operation all without any moving parts. Key to its versatility was the ability to branch; it could trigger different operations that depended on the sign of a computed result. ENIAC plan from Report on the EINAC, 1946.

9 ENIAC: How Did It Work? ENIAC used ten-position ring counters to store digits; each digit used 36 vacuum tubes, 10 of which were the dual triodes making up the flip-flops of the ring counter. Arithmetic was performed by "counting" pulses with the ring counters and generating carry pulses if the counter "wrapped around", the idea being to emulate in electronics the operation of the digit wheels of a mechanical adding machine.

10 ENIAC: How Did It Work? ENIAC had twenty ten-digit signed accumulators which used ten's complement representation and could perform 5,000 simple addition or subtraction operations between any of them and a source (e.g., another accumulator, or a constant transmitter) every second. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher due to parallel operation. ENIAC accumulators

11 ENIAC: How Fast? In one second, the ENIAC (one thousand times faster than any other calculating machine to date) could perform 5,000 additions, 357 multiplications or 38 divisions. The use of vacuum tubes instead of switches and relays created the increase in speed. But it was not a quick machine to reprogram. Programming changes would take the technicians weeks, and the machine always required long hours of maintenance.

12 ENIAC: Women in Technology The six women who did most of the programming of ENIAC were inducted in 1997 into the Women in Technology International Hall of Fame. The programmers were Kay McNulty, Betty Jennings, Betty Snyder, Maryln Wescoff, Fran Bilas, and Ruth Lichterman.

13 ENIAC: Applications It took the team about one year to design the ENIAC, and 18 months and $500,000 in taxes to build it. Completed in 1946 after WWII was over, the ENIAC was used by the military for calculations for the design of a hydrogen bomb, weather prediction, cosmic-ray studies, thermal ignition, randomnumber studies and wind-tunnel design. Research on the ENIAC also led to many improvements in the vacuum tube. Rows of vacuum tubes for the ENIAC

14 ENIAC: The End of the ENIAC On October 2, 1955 at 11: 45 pm, the power to ENIAC was removed. In 1996, students and faculty at Penn s School of Engineer developed a square chip of silicon measuring 0.25 inches (8 mm) on a side was built to the same functionality as the ENIAC, which occupied a large room. Although this 20 MHz chip was many times faster than the ENIAC, it was still many times slower than modern microprocessors of the late 90's. ENIAC CHIP Vacuum tubes 18,000 none Transistors none 250,000 Resistors 170,000 none Capacitors 10,000 none Footprint 80x3 ft 8x8 mm Clock speed 100 khz 20 MHz* Power 1 74 kw 0.5 W* *estimated

15 ENIAC: Where Is It NOW? School of Engineering and Applied Science, University of Pennsylvania: 4 panels, and 1 function table. Smithsonian National Museum of American History: 5 panels London Science Museum: 1 Receiver unit. Computer History Museum, Mountain View, CA: 1 panel University of Michigan, Ann Arbor: 4 panels. U.S. Army Ordnance Museum, 1 function tables. Perot Systems, Plano TX: 1 panel.