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

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
Unsung heroes Copyrighted image Icon Copyright: BBC article icon

History & The Arts 

Unsung heroes

LCD ( Liquid Crystal Display) technology plays a vital role in today's electronic industry, not least in computers and mobile phones. But who developed it, and how?

Article
Medicine transformed: on access to healthcare Copyrighted image Icon Copyright: Used with permission free course icon Level 2 icon

History & The Arts 

Medicine transformed: on access to healthcare

Access to healthcare is important to all of us. Did the arrival of state medicine in the twentieth century mean that everyone had access to good medical services? If you fell sick in 1930 where could you get treatment from a GP, a hospital, a nurse? This free course, Medicine transformed: On access to healthcare, shows that in the early twentieth century, access to care was unequally divided. The rich could afford care; working men, women and children were helped by the state; others had to rely on their own resources.

Free course
15 hrs
Medical discoveries in your area Creative commons image Icon Jerry Evans under CC-BY-SA licence under Creative-Commons license article icon

History & The Arts 

Medical discoveries in your area

Everywhere in Europe has some sort of medical claim to fame. Open University staff around the country share their local heroes.

Article
X-Ray specs Copyrighted image Icon Copyright: BBC article icon

History & The Arts 

X-Ray specs

The role of X-Ray crystallography in the discovery of DNA.

Article
The origins of ancient medicine Copyrighted image Icon Copyright: Production team article icon

History & The Arts 

The origins of ancient medicine

Eleanor Betts explores how the craft of medicine began to develop in the ancient world in the Mediterranean and Near East.

Article
A Brief History of Science Creative commons image Icon Kevin Labianco under CC-BY-NC-ND licence under Creative-Commons license article icon

History & The Arts 

A Brief History of Science

From the discovery of metals up to mapping the human genome, take a quick crash through the development of scientific knowledge.

Article
Tour of John Murray Publishers Copyrighted image Icon Copyright: John Murray video icon

History & The Arts 

Tour of John Murray Publishers

John Murray, descendent of Darwin's original publishers, gives us a tour of the offices where biology - and literary - history were made.

Video
10 mins
The Birth of Modern Computing Copyrighted image Icon Copyright: BBC article icon

History & The Arts 

The Birth of Modern Computing

The history of warfare has been a history of data as well as of violence - knowing your enemies' movements and plans has always been vital; keeping track of supplies and reinforcements crucial. But the Second World War was a conflict where the ability to use machines to crunch numbers proved decisive, as Mike Richards explains.

Article