Skip to content
  • Audio
  • 5 mins
  • Level 1: Introductory

Colossus

Updated Tuesday 26th May 2009

At the heart of the code-breaking effort during WWII was an incredible piece of engineering - Colossus - the world's first programmable computing device.

So what was Colossus? On behalf of Digital Planet, Gareth Mitchell talks to Tony Sale about The Colossus Rebuild Project at The National Museum of Computing (based in Bletchley Park, UK).

Audio

Copyright Used with permission

Text

Tony Sale

Colossus was designed in World War II to break the German Lorenz cipher.  And the Lorenz SZ42 cipher machine was used literally by Hitler to his generals, so very important messages being sent enciphered on that, and it was absolutely top grade, top secret stuff and it needed Colossus to be able to find the settings the German operator had used on an intercept that we’d got, because they transmitted their cipher text by teleprinter, by radio, and we intercepted those signals but then we had to find the settings the German operator had used on his Lorenz machine before we could decipher the message. 

Then when you’d found those settings, you then plugged up those settings on our equivalent of the Lorenz SZ42 cipher machine.  Now we never had a Lorenz machine here in World War II, we never even saw one until right at the end of the war, but because of a horrendous German mistake, 30th August 1941, we managed to find out how the Lorenz machine worked and we were then able to build our equivalent, which was called Tunny. 

This is the intercepted message punched onto paper tape in the Baudot-Murray code and then loaded onto Colossus as an endless loop and being analysed over and over again by Colossus, because Colossus has got no memory, it’s a machine which is switched programme direct logic, very, very fast and very parallel.  It’s got no memory, so it has to read the cipher text over and over again, analysing it statistically and teasing out the wheel settings used to encipher it. 

You’ve got five different counters here, five sets of lights, and they show the counts of the match down the tape in thousands, hundreds, tens and units, for each of those five algorithms you're trying on there, and then the lower panel shows the actual wheel start positions that you're using at this moment to do that comparison.  And it’s those wheel start positions that you're changing, looking for the maximum scores, which tells you you’ve found the right positions. 

(2’16”).

And if that whetted your appetite about the Colossus, here's another way of looking at it. Once again, the Digital Planet team made use of Microsoft's experimental Photosynth service, and turned a bunch of snapshots into something much more than the sum of its parts. The original photos are all courtesy of Digital Planet's resident commentator, Bill Thompson.

Colossus photosynth Copyrighted image Icon Copyright: Production team

Colossus photosynth

Want to try making your own Photosynths? You can do it with a pair of free programs. It only works on Windows XP and Vista, and you'll need to have a Windows Live ID. Download the Photosynth applications.

If you don't have a Windows PC, but do have an iPhone or an iPod Touch, you can create similar images with iSynth, which brings Photosynth to your mobile. Find out more about iSynth.

Find Out More

If digital photography is your thing, why not check out the Open University short course Digital photography: creating and sharing better images (delivered online and available worldwide).

 

For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?

Other content you may like

Forth Road Bridge Copyrighted image Icon Copyright: Used with permission free course icon Level 1 icon

History & The Arts 

Forth Road Bridge

Scotland's Forth Road Bridge may not be the most beautiful bridge over the Firth of Forth, but it is an incredible feat of engineering and is integral to the economy of the entire area. However, rust is threatening to destroy the cables that suspend the road. This free course uses video to explore the issues associated with the potential demise of this great bridge.

Free course
1 hr
Medicine in 14th Century Venice Copyrighted image Icon Copyright: Used with permission article icon

History & The Arts 

Medicine in 14th Century Venice

Treatments were made from a variety of ingredients, both herbal and mineral. John Henderson has found evidence that treatment of the soul was as important as that of the body.

Article
Waves and particles Copyrighted image Icon Copyright: BBC article icon

History & The Arts 

Waves and particles

Explore the nature of light and how our understanding has changed over time

Article
What Did Gutenberg Invent? - The  printing process Copyrighted image Icon Copyright: Production team article icon

History & The Arts 

What Did Gutenberg Invent? - The printing process

Gutenberg is credited with inventing the printing process but what, exactly, did he invent? The details are somewhat sparse.

Article
Origin Day Lecture: Audience Question Six Copyrighted image Icon Copyright: British Council video icon

History & The Arts 

Origin Day Lecture: Audience Question Six

Would the panel care to comment on the grip that creationism has on the minds of the wider public?

Video
5 mins
A short history of the early days of artificial intelligence Copyright free image Icon Copyright free: Archive.org article icon

History & The Arts 

A short history of the early days of artificial intelligence

Artificial Intelligence seems very much of our time - but as Jessica Riskin explains, history records many attempts to create machines that think.

Article
Bridges and Buildings: The structures of the Industrial Revolution Copyrighted image Icon Copyright: Production team article icon

History & The Arts 

Bridges and Buildings: The structures of the Industrial Revolution

Dr Peter Lewis takes a look at the impact that the industrial revolution had on bridge building.

Article
Einstein: The Expert View Copyrighted image Icon Copyright: Used with permission article icon

History & The Arts 

Einstein: The Expert View

Bob Lambourne, Head of the Open University Physics and Astronomy Department, tells the story of Albert Einstein's life and explains why his contribution to science is so important.

Article
Origin Day Lecture: Audience Question Four Copyrighted image Icon Copyright: British Council video icon

History & The Arts 

Origin Day Lecture: Audience Question Four

Could the panel list the tools of science that we can use at home to develop the future of biology?

Video
5 mins