My visit to Bletchley Park and The UK Computing History Museum in November 2017

Regular readers know that I’ve studied the history of computing for a very long time. About four years ago (November 17, 2017) I had the good fortune to visit Bletchley Park and the UK’s National Museum of Computing, outside of London. They are contiguously located, so it was easy to visit both, and well worth the trip. I’ve been meaning to write up a brief account since the visit, and finally made the time.

Both of these museums highlight the role of mathematics and computing in the UK war effort in the late 1930s and 40s, which was only made public in the 1990s. Code breaking featured prominently, as did Alan Turing. In Bletchley Park they’ve kept some of the offices just as they were, so it’s wonderful to be in that space and imagine what it was like to work there.

Here’s a picture of Alan Turing’s office as it looks now (and looked then):

Here’s a wonderful sculpture of Turing:

This funky 1990s era website has a lot of juicy historical detail, so if you’re feeling adventurous, check it out.

I found the recreated Colossus computer to be the highlight of the trip to the National Museum of Computing. When British Telecom (BT) started decomissioning their vacuum tube equipment in the 1980s and 1990s, some clever folks realized they could use the original design schematics for Colossus to rebuild it using the tubes from BT. The original machine is long since gone, but they made an exact replica, and it works!

It’s a special purpose computer in the purest sense. Its sole purpose was to break German Lorenz cipher. There is no clock as we understand it now, the machine is driven by a paper tape that runs in a loop. Each character is composed of 5 bits, and the machine could process 5,000 characters per second. It has 2,500 tubes, some argon filled, the rest vacuum tubes. Total power draw in operation is 8 kW.

I met Phil Hayes, the Chief Colossus Engineer, and asked him if there was any way to convert the 5,000 characters per second into something comparable to “instructions per second” or another more modern unit of performance. Phil was pretty sure that wasn’t possible, due to the specialized nature of the tasks performed by this computer.

Here’s a photo of me with Phil in front of Colossus:

Click on the link below to download a video of Colossus in operation (the sounds are great!). It’s a big file (46 MB) but worth the download:

Download video of Colossus in operation

If you are interested in the history of computing and are in and around London, by all means take the trip to Milton Keynes and check out these two world class museums.