The Odyssey of the eniac a philadelphia Story

The Odyssey of the ENIAC

• A Philadelphia Story

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

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

Babbage and Lovelace

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

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)

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

Other Wartime Efforts

• Code breaking

• Richard Lewinsky provided the British 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

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)

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

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)

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)

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

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

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

Some Skepticism

• compared to a differential analyzer

• digital instead of analog
• electronic instead of mechanical

• tubes had bad reputation for blowing

• MIT crowd opposed

“Give them 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

• Thorstein Veblen, a famous economist, influenced the committee to give them the money

This is a test

• The ENIAC consisted of 17,480 tubes operating at 100,000 pulse 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”

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

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

Early Programmers

Going into business for themselves

• Mauchly and Eckert had a dispute with the university of 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

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)

Remington Steal

• The fledgling Eckert-Mauchly Computer Corporation had underestimated 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

References:

• Some URL’s

• http://homepage.seas.upenn.edu/~museum/
• http://www.library.upenn.edu/special/gallery/mauchly/jwmintro.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