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Dead medium: The Bletchley Park Colossus
From: Bruce Sterling
Source(s): Tony Sale, FBCS.

(((This article by Tony Sale came my way through the

Fringeware list. Mr. Sales' narrative illustrates just a

few of the steep technical, financial and social

difficulties involved in resurrecting dead Big Iron.

Presumably the reborn Colossus is now up and running. I'd

be interested in an eyewitness account of the appearance

and function of this living media fossil.)))

The Colossus Rebuild Project
Helping to save Bletchley Park

by Tony Sale, FBCS.

The switching on of the rebuilt Colossus on Thursday

6th June 1996 by His Royal Highness the Duke of Kent KG.

Briefing notes.

Colossus was the first large electronic valve computer in

the world and it was fully operational in the Spring of

1944, helping to break the German Army High Command

messages enciphered using the Lorenz cipher machine. By

the end of WW II, ten Colossi were operating in Bletchley

Park, the home of Allied code breaking operations. Each

one of them used 2,500 electronic valves and they

represented a major technological triumph for British


Designed by Dr Tommy Flowers and his team of

engineers at the Post Office research labs at Dollis Hill,

and manufactured at great speed, they contributed

significantly to the war effort by the intelligence that

they revealed before and after D Day, 6th June 1944.

The Colossi were special purpose, high speed logic

calculators of great reliability. They were kept switched

on and running 24 hours a day and operated by girls from

the Women's Royal Naval Service, the WRENS.

The very existence of the Colossi was kept a closely

guarded secret and unfortunately all but two of them were

totally destroyed at the end of 1945. The reasons for this

are still not clear. A blanket of silence descended on

everything to do with Bletchley Park and this has, until

now, prevented Colossus taking its rightful place as one

of the greatest achievements of British technology.

It has also allowed the Americans, for far too long,

to claim that their ENIAC computer, which first ran in

1946, was the first large electronic valve computer in

the world.

The first revelations about Colossus appeared in

1970 when Jack Good, one of the wartime code breakers,

gave a brief description in a journal article. This was

followed in 1972 by further revelations by Donald Michie,

another of the code breakers, and then by the researches

of Prof Brian Randell. But even then Colossus was

classified as secret and only a few photographs and

general details were allowed out.

In 1993 Tony Sale had just finished working at the

Science Museum in London restoring some early computers

back to working order. Having studied all the available

meagre details about Colossus, he decided that given his

early career in valve electronics, his involvement with

Ml5 and subsequent long career in computing, it would be

possible to rebuild a working Colossus.

An approach to GCHQ resulted in all the hardware

details about Colossus being declassified, and a further

set of wartime photographs emerged from GCHQ archives.

Some of the original engineers were still alive, including

Dr Tommy Flowers, and they were all enthusiastic about

such a project. Work began in November 1993 to reproduce

machine drawings from the photographs. (All the original

drawings had been destroyed in 1960). All attempts at

getting sponsorship for the project failed, and Tony Sale

and his wife Margaret decided to put their own money into

it in order to make a start since, in view of the age of

the original engineers, time was of the essence.

By July 1994 all the gathering of information had

been done and the construction phase of the project was

inaugurated by His Royal Highness the Duke of Kent KG in

Bletchley Park on the 18th July. The Bletchley Park Trust,

of which Tony Sale is Museums Director, has kindly made

space available and the construction has taken place in

the actual room in H Block where Colossus number 9 stood

in WW II.

Two years of hard work helped by an ever growing

band of volunteers, including some members of the Computer

Conservation Society, and some gratefully received

financial donations has resulted in 90% authentic rebuild

of Colossus which will now be able to demonstrate its code

breaking feats of WW II.

His Royal Highness has kindly agreed to switch on

Colossus at 10.00 am on Thursday 6th June 1996, an

auspicious occasion since it is the anniversary of D Day

for which Colossus helped to provide vital intelligence


For further Information contact Tony Sale on 01908

645001 or 01234 822788, or by fax on 01908 247381, or by