(((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.
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 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