Paper Tape (was: Let's develop an open-source media archive standard )

From: Jules Richardson <>
Date: Fri Aug 13 16:36:38 2004

On Fri, 2004-08-13 at 20:27, ben franchuk wrote:

> "In order to break the Lorenz codes in a reasonable time the cipher text
> had
> to be repeatedly scanned at very high speed. This meant at least 5,000
> characters per second and in the 1942 this implied hard vacuum photocells
> to optically read the holes in the paper tape.

Actually flat-out the Colossus reader can manage around 8000 chars/sec
IIRC. I'm sure that Cliff (one of the other guys who looks after the
Colossus rebuild) has mentioned to me before that they've had problems
with the tape wearing the metal pulleys on the tape frame before with
those kinds of speeds.

They seem to be letting the public stand in the H Block machine room
itself at the moment (rather than previously whereby the public were
kept in a windowed viewing room) so it's a good time to go and see the
rebuilt Colossus running.


Received on Fri Aug 13 2004 - 16:36:38 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:36:34 BST