Computers Between 1940-50’s

Prof. Jim AustinUniversity of York

Part time curator of The Jim Austin Computer Collection

The generations

Mechanical – pre-generations 1st Generation : Valves and electro-

mechanical. 1940’s-50’s 2nd Generation : Transistors 1953-70’s 3rd Generation : Small scale IC’s 80’s 4th Generation : Large scale IC’s 90’s

Charles Babbage(1791-1871) Widely recognised

as the father of computing.

Famous for designing: Difference Engine Analytical Engine

Note – his brain is in the science museum!

Difference Engine - 1822

Analytical Engine

As the barrel turns, studs on outer surface operate different mechanisms.

This process was internal to the engine, a fixed micro-program.

Analytical Engine

Babbage’s programming cards Inspired by the how weaving machines were

programmed

An example of an Electro-mechanical computer

Powers-Samas Tabulator – 1940’sin the Collection

First generation Computers

Relay computers: Z3 Harvard Mark 1

Valve computers: ENIAC Colossus The Baby Manchester Mark 1 EDSAC

Konrad Zuse (1910 - 1995)

No significant attempts to build a general purpose computer were made after Babbage’s death until the 1930’s.

The first examples were the Z1 and Z3, discovered after World War II.

Constructed in Germany between 1936 - 1941.

Z3 - 1941 The Z3 was entirely

constructed using relay technology.

Programmed using punched tape and user console.

Possibly the first complete programmable computer

Relay LogicAND Z = A&B

OR Z = A+B

NOT Z = A

FLIP FLOP

Z3 Instructions implemented

using a micro sequencer constructed from stepwise relays.

Instruction overlapping used i.e. read next instruction whilst writing result.

Fast addition using carry look-ahead circuit constructed from relays.

Harvard Mark 1 - 1944

The Mark 1 was developed by Howard Aiken and built by IBM between 1939 - 1944.

Also known as the IBM Automatic Sequence Control Calculator (ASCC).

Harvard Mark 1 Constructed from electromechanical relays, 55

feet long, 8 feet high, 2 feet deep, weighed 5 tons, relatively slow and very noisy.

Numbers (23 decimal places) were stored mechanically using 3000 electromagnetic decimal storage wheels. It also had 1400 rotary dial switches connected by 500 miles of wire.

The Harvard Mark 1 was used by the US Navy for gunnery and ballistic calculations until 1959, but was out of date by the time it was commissioned.

Harvard Mark 1 He also developed the concept of the Harvard

computer architecture.

ENIAC - 1944

Electronic Numerical Integrator and Computer.

ENIAC

Commissioned by the U.S. Army to calculate firing tables for specific weapons for a range of environments and weather conditions.

ENIAC ENIAC was completed in May 1944 and has a

strong claim (by USA, wrong) to be the first ever general purpose electronic computer.

Developed by a team lead by J.P.Eckert and J.W.Mauchly.

Decimal computer, used more than 18,000 valves, 100 by 10 by 3 feet, weight 30 tons.180,000 Watts

Faster than anything that had been built previously; multiplication in under 3 ms.

Described as being “Faster than thought”.

ENIAC

Programming!

Hollerith Reproducer type 202

Reproducing punch

Thermionic valves.

Valve Logic

NAND Z = (A&B)

OR Z = A+BFLIP FLOP

Colossus - 1943 Used in WWII to crack the German codes

written on Lorenz machines

Colossus

Baby - 1948

This is a replica in the Manchester Museum of Science and Technology built in 1989

Manchester Baby(Small Scale Experimental Machine) Ran first stored programme on June 21st 1948

32-bit word length Serial binary arithmetic using 2's complement integers A single address format order code (instructions!) A random access main store of 32 words, extendable up to 8192

words A computing speed of around 1.2 milliseconds per instruction

It is almost true that the photos of the replica Baby are the most accurate pictures of the original (!)..

(From History ofManchester ComputersLavington, 1975,NCC publications.)

The worlds first stored program.(amended)Tom Kilburn7 instructions inInstruction set

Highest factor of 218

Manchester Mark 1

The machine built after baby… 40,000 Watts, used more than 4000 valves.

Manchester Mark 1

Williams tubes

Manchester Mark 1

Mercury Delay line memory

Manchester Mark 1

Drum store Relatively slow, but had 16 times the capacity of

the random access CRT store.

EDSAC – 1949 Cambridge University

Electronic Delay Storage Automatic Calculator

An EDSAC II module in the collection

Pegasus computer - 1956

The Transistor Computer - 1953

The first experimental transistor computer

The Transistor Computer Constructed at Manchester University in 1953. Used

200 point contact transistors 1300 point diodes 150 watts.

Main memory drum store which meant that the transistor computer

was slower than the Mark 1.

Marconi Transistorised Automatic Computer.

Wylfa Nuclear Power Station, BNFLInstalled Oct 1966, switched off 2004 after 38 years of operation.Half at Bletchley.

Marconi TAC - 1966

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