It's All About the Datasheets!

A project log for WITCH-E Decimal Based Computer

Document and create a modern replica of the Harwell Dekatron computer known as the WITCH

Dave's Dev LabDave's Dev Lab 09/17/2017 at 20:553 Comments

In the effort to translate and convert the WITCH design from using Cold Cathode Valves (aka tubes) into modern components, it was essential to understand how each of the valves worked and how they were being used in the system. As someone who grew up in the age of the transistor, I was completely unfamiliar with practical applications of using valves. This is where the engineer in me kicked in. The first order of business was to find datasheets on every component I could identify. The WITCH schematics and maintenance logs had very good details about the model and type of devices being used. I quickly found on the net The Valve Museum. Most of the parts I was looking for were documented there with datasheets and pictures! Now with datasheets in hand, I was able to start working backwards on how exactly these engineers created a working computer from "stone knives and bearskins"!

EDIT: pictures and pdf datasheets are available via the WITCH-E Project github repository under datasheets


Dr. Cockroach wrote 09/17/2017 at 23:27 point

Cut my teeth on tubes when I first got into Ham Radio back in 1974. I have not worked with them for many, many years. You have a fantastic project here and I will keep watching :-)

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Dave's Dev Lab wrote 09/18/2017 at 00:14 point

thanks! i need to work on more documentation though, and really work on the educational aspects. i really had hoped for more engagement from the community with the project, but i'm continuing on anyway...

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Dr. Cockroach wrote 09/18/2017 at 00:32 point

Up until your project, I had never heard of the WITCH. Reading what you have shared and watching the videos has helped me to not give up on my own problem child ;-)

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