Re: Colossus (fwd)

Forwarded from J. V. Field :
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---------- Forwarded message ----------
Date: Sun, 2 Nov 2014 22:42:19
From: J V Field <ubwc039-DEIF+Y36/[email protected]>
To: Martin Postranecky <mp-/[email protected]>
Cc: J V Field <[email protected]>
Subject: Re: [BPARK] Colossus

Dear Dr Postranecky,

     As I cannot send items to the BP list, I append and item that 
youmgith iekto forward to it.

J. V. Field

In reply to Bill Rodgeway

>  There were 10 Colossus computers.

  Yes. ScM got that right.

>Where were they located

   Block H, now the National Museum of Computing, and Block F, demolished 
by the GPO when it ownd the site, and now a car park.

> and how was the workload for each of them organised please?

  Not so easy to answer. My impression (from reading the Report of Max 
Newman;s group) is that each Colossus was working on a particular message 
or a small group of messages from the same day.

> (Did they each work on different aspects of code breaking?)

  No.  They were used in statistical breaking of teleprinter (i.e. 
non-Morse) messages that used the Tunny cipher.

>  Was a Bombe machine assigned to each Colossus

  No.  The bombes were used against Enigma messages, which were in Morse 
and in a completelt different cipher

  In June 1945 there was some discussion (inside GCCS) about whether some 
of the machines designed for use against teleprinter ciphers could be used 
for analogous work against other ciphers. It is probably in connection 
with these discussions that the Report of Newman's group points out that 
the Colossus machines were not as adaptable as Robinsons. I do not know 
whether there is any record of the latter being used against any cipher 
other than Tunny.

  And, as far as I know, nothing definite is known about the uses to which 
the Colossi that were moved to GCHQ were put after the war.

J. V. Field