Form 5 pupils studying Computer Science travelled to Bletchley Park to visit the National Museum of Computing, which houses the largest collection of historic functional computers in Europe.
One of the pupils, Tom, tells us what he learnt from his trip:
“Bletchley Park is a Second World War compound where allied scientists worked on decrypting Nazi messages. Most of these messages were encrypted by an enigma machine, an encoding device.
The Enigma machine had sets of wires and cogs, which changed the letters of a message in a way which was very hard to decode by hand. It involved the manipulation of letters which didn’t have a clear pattern. The device had one hundred fifty-nine million million million combinations for different keys. Also, the key to decrypt the messages would change every day so workers would only have twenty-four hours to work out the key for that day.
To help decipher the codes created by the German Enigma machine, the Turing Welchman Bombe computer was developed. This computer was made up of multiple enigma machines which ran through all the possible combinations, ignoring all impossible combinations. This machine, paired with two other smaller machines, would be able to decode the German enigma key in three hours. The machine was pivotal in the allied side winning the Second World War.
The Nazis also had other encryption machines, one being the Lorenz SZ42, which were used by German high command and had many more times as many combinations for decryption keys. The Turing Welchman Bombe wasn’t powerful enough for this device and it, therefore, led to the Bletchley team creating three more computers, one being the first actual computer. The first computer was capable of data input, processors, memory and the ability to output data. The first two devices were used together and were the Tunny and the Heath Robinson. These two computers worked together to decrypt messages using XOR logic and statistical calculations to find out which combinations would be possible. These machines aren’t considered to be computers as they didn’t have a diagrammatic structure, a feature which defined a computer. These computers were then improved on and made into the colossus, the first computer, which had a diagrammatic structure and could store data and decode messages by itself.
The Second World War ended but the development of the computer didn’t. The Harwell computer, later known as the Wolverhampton Instrument for Teaching Computing from Harwell (WITCH) was created and is a more powerful computer which could be programmed to do mathematical calculations. It could also store data in dekatrons, lights which pointed to a digit on its face. This computer was the beginning of Von Neumann architecture. It had an accumulator to collect instructions and ALU to carry out instructions. This computer still didn’t have an operating system though, as it was fed programs through strips of paper. These programs were just instructions for arithmetic operations.
This all links back to our GCSE course as it relates to the development of the computer and Von Neumann architecture and how computers have become what they are today. It also related to encryption, a topic in our syllabus. I think using the real-world examples of the enigma machine helped my understanding of the topic as a whole. Overall, I really enjoyed the trip.”