1. The Odyssey of the ENIAC A Philadelphia Story

2. ENIAC Electronic Numerical Integrator And Computer It was completed in 1946 at the Moore School of the University of Pennsylvania The two driving forces behind it were John W. Mauchly and J. Presper Eckert

3. Not the first computer In 1839 Charles Babbage designed what he called the “difference engine” It was a mechanical digital computer It was distinct from other computing devices in that it could be programmed One of the earliest programs was written by Ada Byron, Countess of Lovelace, who assisted Babbage and supported him financially

4. Babbage and Lovelace

5. Not the first electronic computer either In the late 1930’s, early 1940’s John Atanasoff and Clifford Berry built a special purpose device from vacuum tubes (the Atanasoff-Berry Computer ABC) –Mauchly (of ENIAC fame) was familiar with this work Around the same time, IBM, known then for its punch-card tabulating machinery was looking into electronic multipliers

6. WAR, what is it good for? With the war came the urgent need to calculate Among other things, vast ballistic trajectory tables (how far shells would fly) were needed The Ballistic Research Laboratory was in Aberdeen (between Philadelphia and Baltimore)

7. Philadelphia With so many colleges and universities in the area, Philadelphia was a good center for these computations Also the Moore School (at Penn) had a “differential analyzer” A differential analyzer is a collection of gears, shafts and wires — a mechanical, analog computer

8. Other Wartime Efforts Code breaking Richard Lewinsky provided the British with the plans for the ENIGMA which allowed Alan Turing and others to break the German’s codes To break a harder code, Turing, T.H. Flowers and M.H.A. Newman built an electronic decoder from vacuum tubes: COLOSSUS Churchill and the Conventry bombing

9. Konrad Zuse built several versions of his computers, known as Z1 through Z4 they were digital and partly electronic, partly mechanical (more and more electronic as he progressed) used his computers for aerodynamic calculations (my main source on Zuse is Zuse)

10. Meanwhile back in Philadelphia The backlog of ballistic computations was growing For example, the ground in North Africa was softer than that in Aberdeen and thus the tables were off and needed recalculating

11. WACs (poetic) Most of this army of calculators were women Previously the Moore School had been all male But they now brought in many women, and this number was supplemented by members of the Army’s Women’s Auxiliary Corps (WAC)

12. The Moore School Players John W. Mauchly (overall visionary) J. Presper Eckert (genius with electronics) John Grist Brainerd (research director of the Moore School) Herman Goldstine (liaison to Aberdeen)

13. Conversations In ongoing conversations, Mauchly and Eckert discussed the computing problems Eckert, despite his youth, has vast experience with electronics, playing with radios and even television from an early age Eckert convinced Mauchly that vacuum tubes would work organ example

14. The lost memo “Purely mechanical … devices can be devised to expedite the work. However, a great gain in speed … can be obtained if the devices … employ electronic means …, because the speed of these devices can be made very much higher than that of any mechanical device.” The memo was filed away or lost, anyway nothing happened for about six months

15. A Brief History of Tubes It started with an effect Thomas Edison noticed while experimenting with light bulbs John Ambrose Fleming discovered that one could exploit the effect to detect radio waves and convert them to electricity, but the signal was too small Lee de Forest added to the device, making the triode; Edwin Armstrong pointed out it could be used to amplify signals

16. Some Skepticism compared to a differential analyzer –digital instead of analog –electronic instead of mechanical tubes had bad reputation for blowing MIT crowd opposed

17. “Simon, give Goldstine the money” they played down the differences to get the proposal past the skeptics they probably only received the backing because of the desperate need at the time Oswald Veblen, a famous mathematician, influenced the committee to give them the money

18. This is a test The ENIAC consisted of 17,480 tubes operating at 100,000 pulses per second In May of 1944, the ENIAC passed the two accumulator test, a trivial mathematical operations, but an amazing feat of engineering Harold Pender, the dean of the Moore School, expressed “moderate optimism”

19. ENIAC’s debut By the time ENIAC was ready, the war was over ENIAC’s first real computations were not on shell trajectories but on thermonuclear chain reactions ENIAC’s formal dedication was in Feb. 1946

20. Programming the ENIAC One drawback to the ENIAC was the way it was programmed — with wires A new program required rewiring Mauchly, Eckert and John von Neumann discussed designs of future computers (like EDVAC) in which the programs (instructions) would be stored in the computer’s memory The bug story

21. Early Programmers

22. Going into business for themselves Mauchly and Eckert had a dispute with the university over the patent Soon after they left and went into business for themselves They started building the UNIVAC (The Universal Automatic Computer) Computers were huge and expensive Skeptics said there were too few customers

23. The first customer The government, in particular, the Census Bureau, was the first customer The Census Bureau has had to deal with the problem of collecting and processing vast amounts of information long before the “information age” They played a role in the making of IBM near the turn of the century (Herman Hollerith)

24. Remington Steal The fledgling Eckert-Mauchly Computer Corporation had under-estimated the project and were seriously strapped for cash They were bought by Remington Rand (maker of type writers) They became Sperry Rand Corporation And finally UNISYS

25. References: Some URL’s –http://homepage.seas.upenn.edu/~museum/ –http://www.library.upenn.edu/special/gallery/mauchly/jwmi ntro.html –http://www.si.edu/resource.tours/comphist/eckert.htm#tc Some books –Engines of the Mind, Joel Shurkin 1984 –Computer: A History of the Information Machine, M. Campbell-Kelly and W. Aspray