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Getting Started! The WITCH Bootrom

A project log for WITCH-E Decimal Based Computer

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

daves-dev-labDave's Dev Lab 09/17/2017 at 02:321 Comment

One of the fundamental aspects of the WITCH-E project is to gain a better understanding of the the original WITCH and document it. Unlike many other retro computing projects where thousands, or tens of thousands of the original computer still exist, there is ONLY one WITCH. With that in mind, I can't really ask to "poke around" on the original, and randomly hook up logic probes, so I had to use a different method for reverse engineering the WITCH. Most of the details I have learned about the machine are from maintenance documents/logs, schematics, and pictures of the machine. One of the research areas I was keenly interested in is how the WITCH initially started up. Modern systems often use Read-Only-Memory(ROM) that contain the systems initial instructions, but what did the WITCH use? I made a short little video of how I figured this little item out, and replicated the functionality....

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David Boucher wrote 09/20/2017 at 18:54 point

Great video Dave, nicely explained.

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