Colossus

Colossus Rebuild Project in H Block The project team, lead by Tony Sale, has obtained Grade II Listing of H Block in an attempt to secure the future for the Colossus Rebuild.
	The Colossus Rebuild is situated in the very room that Colossus 9 once stood. Colossus (as seen in October 1999) is nearing completion. The tape-pulley system is complete and the paper tape runs up to speed and is easily scanned by the optical reader system. Two out of the five code elements are working, only another 3 circuit elements to duplicate!
\| EXIT \| The Early Days \| The Equipment \| Milestones \| The Lexicon of Cryptography \|

The Early Days

The Bedstead in October 1994
This was the state of Colossus in October 1994. 'The Bedstead' was assembled and a new tape drive/ pulley system was in the process of being re-engineered.

The Equipment

A comparison of types of uniselectors which could have been used in the rebuild.

Milestones

On 18th July 1994 HRH The Duke of Kent formally opened the Bletchley Park Museums and inaugurated the Colossus (Mark 1) Rebuild Project.
On 6th June 1996 (the anniversary of D Day) HRH The Duke of Kent came back and formally switched on Colossus in the presence of its designer Tommy Flowers.
On 20th May 2004, Tony Sale videoed the further developed Colossus Mk 2 setting all five K wheels on the BREAM cipher text.
On 1st June 2004, the 60th anniversary (1944-2004) of a Colossus Mk 2 in Bletchley Park, a video of the rebuilt Mk 2 was shown to 120 people at a commemorative event in the Science Museum in London.
On 17th December 2004, after careful consideration of all the evidence, including advice from English Heritage, the Secretary of State decided to List H Block as a Grade II building. It was added to the list having been judged to be a building of special architectural or historic interest.
2005 the Mk2 rebuild continues, while the ultimate fate of Bletchley Park as a whole site is still uncertain.

BP Trust Press Release 19th August 2005

"The room in Block H that contains a rebuilt version of the Colossus computer will be preserved. The rebuild, a project led by Tony Sale and a team of dedicated volunteers for almost 15 years, will remain in situ and will be viewable by heritage and other visitors to Bletchley Park, provided that revenue-generating activities such as income from visits, conferences, rentals and the like can be found to meet the site’s considerable running costs."

The Lexicon of Cryptography ('Most Secret', Bletchley Park 1943)

To assist in cracking the German intercepts, a whole vocabulary of terms evolved and were recorded in a 'Lexicon of Cryptography.'

CRIB

A piece of evidence (usually a captured code book or length of plaintext) which provides clues for the breaking of a cryptogram. Codebreaker, Tilly Knox is said to have stated "..without question, the crib... is the single most essential tool of any cryptanalyst."

CRYPTOGRAM

A message written in cipher or in some other secret form which requires a key for its meaning to be discovered.

KISS

The coincidence of two different cryptograms, each transmitted in a different cipher, yet containing the same original plaintext, the solution of the one thereby leading to the solution of the other.

PINCH

To steal enemy cryptographic material. Any object stolen from the enemy that enhances the chances of breaking his codes or ciphers.

PLAINTEXT

The original, intelligible text, as it was before encipherment, revealed after successful decoding or cryptanalysis.

STRIP

To remove one layer of encipherment from a cryptogram which has been subjected to the process of super-encipherment. In essence, a message which has been coded once and then re-encoded to give twice the security.

WHISPERS

The sounds made by an enemy wireless transmitter immediately before it begins to broadcast a coded message.

Return to Index

Acknowledgements: 'Lexicon of Cryptography' from ENIGMA, a novel set against the historical background of events at Bletchley Park, by Robert Harris.

	This was the state of Colossus in October 1994. 'The Bedstead' was assembled and a new tape drive/ pulley system was in the process of being re-engineered.