today’s topics lecture 10: the coming of eniac

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The ENIAC

History of Computing

Slide 1

Lecture 10:

The Coming of Eniac

based on Williams Chapter 7

Today’s Topics

Wartime DevelopmentKonrad Zuse 1910-95

Zuse Z1Digital Electronics: Main Steps

ABCThe Eniac

Cradle of InventionEckert & MauchlyA Vital MeetingThe Machine

Analysis of EniacJohn Von NeumannDelay Line Memory

The ENIAC


Slide 2

Wartime DevelopmentsElectronics development was increased by the war:

•Radar

•Atomic energy (bomb) calculations

•Coding and deciphering machines

•Electronic calculators.

15 Seconds after test detonation

The ENIAC


Slide 3

Konrad Zuse 1910-95Konrad Zuse is popularly recognized in Germany as the inventor of the computer.

He built a mechanical device, which he (much later) called ``Z1'', in the living room of his parents' apartment in Berlin.

The construction of the Z1, the first programmable binary computing machine in the world, began in 1936 and finished in 1938.

Konrad Zuseworkingon a Z4 Computer (1942).

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The ENIAC


Slide 4

Zuse Z1In many ways the Z1 was a remarkable machine.

Z1 used punched tape memory, had a binary floating point unit, a control unit and binary-decimal-binary converters.

The Z1 was the first programmable, binary based machine in the world!

The building blocks of the Z1were thin metal sheets.The Z1 computer in the living room

of Zuse's parents in 1936

The ENIAC


Slide 5

Digital Electronics: Main StepsThere were three main steps to the development of digital electronics:

Atanasoff-Berry Computer (ABC)

Colossus

ENIAC (Electronic Numerical Integrator and Computer)


The ENIAC


Slide 6

ABCAtanasoff (1903-95) was of Bulgarian origin.

He wanted a better calculator for his mathematical calculations and produced an electronic calculator with a regenerative memory.

He was helped by his assistant Clifford Berry. Berry later committed suicide andAtanasoff was publicity-shy.

This didn’t help when there was a controversy about Mauchly (ENIAC) stealing Atanasoff’s ideas in 1940.


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The ENIAC


Slide 7

The ENIAC


Slide 8

The ABC in 1942

Clifford Berry with the actual ABC

The ENIAC


Slide 9

Berry 1962

Atanasoff 1983

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The ENIAC


Slide 10

The Eniac

Although NOT the first electronic computer, Eniac was a very important machine as it signalled a huge advance in electronic computing.

President Truman in front of ENIAC (U.S. Army photo, from archives of ARL/SLAD/BVLD,

courtesy of Mike Muuss ).

The ENIAC


Slide 11

Cradle of Invention

The Moore School of Electrical Engineering, University of Pennsylvania collaborated on research with the U.S. Army Ordnance Department Ballistic Research Laboratory at the Aberdeen Proving Ground in Maryland.

The Ordnance department had to create complicated ballistic firing tables so that soldiers could aim guns etc. accurately.

A collage depicting the Moore School during WWII, showing Mauchly in classroom.

The ENIAC


Slide 12

Eckert & MauchlyJohn Mauchly and J. Presper (Pres) Eckert were the main driving force.

Eckert was the electronics expert and was a laboratory instructor.

Mauchly was professor of physics atUrsinus College, Philadelphia.

They met at the Moore school on a training course for the war. They chatted whilst others toiled.

Mauchly then joined the staff. He was interested in weather forecasting.

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The ENIAC


Slide 13

A Vital MeetingMauchly met Atanasoff in 1940 and visited him during summer 1941. This led to discussions with Eckert on electronic calculations.

He wrote a paper on the subject in August 1942 and showed a huge increase in the number of calculations per second.

Early 1943 ballistics tables had fallen behind schedule.

Ballistics lab and Moore school decided to build ENIAC based on Eckert’s report.

The ENIAC


Slide 14

The MachineThe design was criticised by other engineers for its complexity.

Eckert was experienced in radar development and drew on for the ENIAC project management.

He allowed for component failure and carefully designed his circuits with this in mind (worse case scenario ).

He also used cheap components, even if less reliable, in preferenceto paying for ultra-reliable, but more, expensive ones.

The complete machine consisted of a large number of individual units set out in a horseshoe shape.

The ENIAC


Slide 15

The Units (1)20 Accumulators.

They acted as a memory for a single 10 digit signed number; and also an arithmetic unit which could add or subtract a number from the one currently stored. They were an electronic copy of the mechanical register used for the Harvard Mark I.

A Multiplication Unit. These circuits worked by carrying out repeated single-digit multiplication.

A combined division and square root unit.

Three function tables, which stored tables of values, by means of switches (Harvard Mark I).

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The ENIAC


Slide 16

The Units (2)An input unit connected to a card reader (120 cards per minute).

An output unit connected to a card punch (100 cards per minute).

The master programmer to control the sequence of operations.

There were 40 front panels, each 2 ft wide.

Each unit was made up of rows of electronic vacuum tubes and relays behind front panels containing •switches•indicator lights •plug socketsto interconnect units.

The ENIAC


Slide 17

Facts and FiguresDimensionsENIAC was 8 ft high, 3 ft wide, 100 ft long, weighed 30 tons and used 140 KW of power.

Components18,000 vacuum tubes of 16 basic types;1,500 relays;70,000 resistors;10,000 capacitors

CostOriginal estimate $150,000 dollars.Final cost $486,804.22

The ENIAC


Slide 18

Hot Stuff!With all this power consumption, ENIAC needed cooling and this was achieved by forcing air over the components (doors shut).

ENIAC up and running in Spring 1945.

Fire!A technician left a door open and the safety switch disabled andtwo units caught fire.

ReliabilityOne vacuum tube out of 150 would fail every week or so.18,000 logic tubes – one failed every two or three days.

BusesThe units were connected via two bus lines which ran the entire length of the machine. One line carried data, the other instructions, the switches determining the precise details.

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The ENIAC


Slide 19

Working with the Eniac

The machine carried out a calculation by plugging a large number of cables between the bus wires and the panels to ensure the data and instructions reach the correct units.

ENIAC programming Exercise

The ENIAC


Slide 20

Analysis of EniacNot enough accumulators;

Multiplication and division were time-consuming – repeated addition;

For a few years it was the only large-scale digital electronic computer in daily use.

Vacuum tubes reliable once warmed-up. Problem with night fire guard. Once solved, ran for next 10 years.

It had neither memory nor stored program (although memory was added later).

The ENIAC


Slide 21

John von Neumann (1)Hungarian, brilliant mathematician;

1993 youngest member of Institute of Advanced Study, Princeton;

Worked on development of atom bomb during World War 2;

Good at report writing;

Science consultant;

Met Goldstine on train platform and found out about ENIAC;

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The ENIAC


Slide 22

John von Neumann (2)January 1944 Eckert considered storing programs electronically, and wrote document on magnetic storage;

September 1944, von Neumann regular visitor and entered into discussions on a new machine EDVAC, which, would store its instructions in its memory and issue these at the same speed as other components.

Von Neumann wrote up a report on EDSAC in June 1945 and he was credited with inventing the stored program and his name is in all the books (von Neumann architecture).

Bitter disputes!

The ENIAC


Slide 23

Delay Line MemoryExercise

Used in EDSAC, EDVAC, LEO and Pilot ACE.

A series of electrical pulses were converted into sound waves using piezoelectric quartz crystal.

These waves would then travel slowly down the tube, which was filled with mercury.

At the other end, they would be detected by another quartz crystal, amplified and reshaped and sent back to the front of the delay line again.

today’s topics lecture 10: the coming of eniac

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