[David Strom's Web Informant] Web Informant, December 1 2014: The collaboration behind Colossus

David Strom david at strom.com
Mon Dec 1 05:12:57 EST 2014

Web Informant, December 1 2014: The collaboration behind Colossus

When I first heard about the heroic efforts during WWII to break the Nazi
communications codes such as Enigma, I had in my mind the image of a lone
cryptanalyst with pencil and paper trying to figure out solutions, or using
a series of mechanical devices such as the Bombe to run through the various

But it turns out I couldn't be more wrong. The efforts of the thousands of
men and women stationed at Bletchley Park in England were intensely
collaborative, and involved a flawless execution of a complex series of
steps that were very precise. And while the Enigma machines get a lot of
the publicity, the real challenge was a far more complex German High
Command code called Lorenz, after the manufacturer of the coding machines
that were used.

The wartime period has gotten a lot of recent attention, what with a new
movie about Alan Turing just playing in theaters. This got me looking
around the Web to see other materials, and my weekend was lost in watching
a series of videos filmed at the National Museum of Computing at Bletchley
Park <http://www.tnmoc.org/explore/colossus-gallery>.  The videos show how
the decoding process worked using the first actual electronic digital
computer called Colossus. Through the efforts of several folks who
maintained the equipment during wartime, the museum was able to reconstruct
the device and have it in working order. This is no small feat when you
realize that most of the wiring diagrams were immediately destroyed after
the war ended, for fear that they would fall into the wrong hands. And that
many people are no longer alive who attended to Colossus' operations.

The name was realistic in several ways: first, the equipment easily filled
a couple of rooms, and used miles of wires and thousands of vacuum tubes.
At the time, that was all they had, since transistors weren't to be
invented for several years. Tube technology was touchy and subject to
failure. The Brits figured out that if they kept Colossus running
continuously, they would last longer. It also wielded enormous processing
power, with a CPU that could have had a 5 MHz rating. This surpassed the
power of the original IBM PC, which is pretty astounding given the many
decades in between the two.

But the real story about Colossus isn't the hardware, but the many people
that worked around it in a complex dance to input and transfer data from
one part of it to another. Back in the 1940s we had punch paper tape. My
first computer in high school had this too and let me tell you using paper
tape was painful. Other data transfers happened manually copying
information from a printed teletype output into a series of plug board
switches, similar to the telephone operator consoles that you might recall
from a Lily Tomlin routine. And given the opportunity to transfer something
in error, the settings would have to be rechecked carefully, adding more
time to the decoding process.

There is an interesting side note, speaking about mistakes. The amount of
sheer focus that the Bletchley teams had on cracking German codes was
enormous. Remember, the codes were transmitted over the air in Morse. It
turns out the Germans made a few critical mistakes in sending their
transmissions, and these mistakes were what enabled the codebreakers to
figure things out and actually reconstruct their own machines. Again, when
you think about the millions of characters transmitted and just finding
these errors, it was all pretty amazing.

What is even more remarkable about Colossus was that people worked together
without actually knowing what they did. There was an amazing amount of
wartime secrecy and indeed the existence of Colossus itself wasn't well
known until about 15 or 20 years ago when the Brits finally lifted bans on
talking about the machine. For example, several of the Colossus decrypts
played critical roles in the success of the D-Day Normandy invasion.

At its peak, Bletchley employed 9,000 people from all walks of life, and
the genius was in organizing all these folks so that its ultimate
objective, breaking codes, really happened. One of the principle managers,
Tommy Flowers, is noteworthy here and actually paid for the early
development out of his own pocket Another interesting historical side note
is the contributions of several Polish mathematicians too.

As you can see, this is a story about human/machine collaboration that I
think hasn't been equaled since. If you are looking for an inspirational
story, take a closer look at what happened here.
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