Manchester University’s CS Legacy

When I chose Manchester University for my Computer Science MSc, it was partially because of its reputation but I realized I didn’t actually know anything specific about that legacy.

I thought I’d find out a little more about some of the computing cornerstones that were laid in Manchester’s labs. Did you know that the first Random Access Memory was created there? Fast, random access memory is a core part of computer systems today. Having enough of it is crucial to making your laptop or desktop run all those applications quickly for you.

The Williams (or Williams-Kilburn) Tube was the first random access memory that could access at speeds suitable for a computer. It was the ancestor of the multi-gigabyte cards you’ll find in your computer today.

Back in the days before TVs were two inches thick, the moving pictures on the screen were drawn by magnetic fields and streams of electrons in a glass tube called a Cathode Ray Tube, or CRT. Did you ever hold your hand near the screen of a CRT television and feel the static tingle? Somewhere around 1946, Tom Kilburn and Freddie Williams at Manchester University used the charge on a CRT’s phosphorescent coating to store ones and zeroes (effectively as dots), where they could be detected by a ‘pickup plate’ which lay over the ‘screen’.

As the electron beam hit the screen, a positive charge would be left behind at that position. Not for long mind you, as the charge would dissipate, but the information read by the pickup plate was used to refresh the tube before the charge had chance to leak away. This refreshing process is still required by the RAM chips in your computer today.

If you’re interested in knowing more, you can read all about it on Wikipedia and computer50.org, the sources I used to get this information.

To test the Williams Tube, the folks at Manchester built the first stored-program computer, a pretty important milestone in its own right. Maybe more on that some other time.