Recently I took 30 pupils to visit the National Museum of Computing at Bletchley Park in Milton Keynes. With all the disruption due to the snow during the week we weren’t sure if we were going to make it, but thankfully the snow cleared and the journey went as planned.
On arrival, pupils were given a briefing by one of our tour guides, Chris, who spoke about how codes and cyphers were used in war times to send secret messages, and still are today to encrypt credit card information when we buy something over the Internet. He then went on to explain how people would try to crack these cyphers to read the messages. The Enigma code was a cypher used by German military using an Enigma machine which could produce a possible 4×1026 different combinations. This code was sent in Morse Code over the radio, so anyone with a radio could listen to it and tell which letters were used, but they were just a random combination of letters. We were told how code breakers at Bletchley Park would spend weeks or even months trying to crack codes, by which time it was too late, so a team lead by Alan Turning developed a machine that would automatically read a paper tape that had holes punched in to represent letters and compare that to a “clues tape” with key words that they would expect such as bomb, bullets and invade, all in German of course. This machine was called Colossus.
After the WWII the machines were dismantled and destroyed and the whole operation was kept a secret so that no other nation knew that we could crack their codes. In 2007 this representation was complete using exactly the same parts that would have been used for the original. We were all fascinated by the amount of lights and valves and wondered how it would work. Kindly, our tour guide switched the machine on and it started to check the two tapes for patterns. It was very noisy and we could imagine how hot it would get in a small secret room.
We then went on to the first ever electrical calculator. In front of it was an old mechanical calculator which would be awkward to use and easy to make mistakes. As scientists started working with atoms and nuclear power, they needed a much more accurate method of making complex calculations so they devised the Harwell Dekatron Computer , which was later renamed by the Wolverhampton and Staffordshire College of Technology as WITCH (Wolverhampton Instrument for the Teaching of Computation).
After lunch we were shown some of the iconic developments in technology, for example this memory disk which was capable of storing a whopping 4KB (enough for a few emails) and this machine which we used to type our name into tape. The we explored the games room, this contained every iconic games console from history such as the Amiga, Commador 64 and Spectrum. Everyone loved playing Pac-man, Space Invaders and games of that era.
We then had a session using BBC Micro computers. These were developed for use in education and were used to teach many computer programmers who now work for massive companies such as IBM, Microsoft and Google. We were given a list of code, out of a computer magazine that would have been available at the time. We had to type in the code into the computer, but once we pressed return we could go back and change it if there was a mistake, so we’d have to type it out again. It was very satisfying to complete the code and get the game working and we all had great fun.
Pupils recorded a blog of their day, with interesting facts and discoveries. There are also lots of photos of what we saw. You can see these at bletchleyparktrip.blogspot.com
or find the link from our website.