I found out you can exit the website and return to continue reading a couple more parts until it brings up the registry page again. Then repeat. Who knows, maybe NSA is so paranoid it keeps track of who's interested.
Fascinating stuff - I'd love to know more about the technical details of the NCR machine since it seems to work in a completely different manner to the Turing Bombe
The Turing Bombe Rebuild Exhibition
"This site is dedicated to Margaret Davies who, during the war, worked on a lathe at BTM Letchworth making components for the Bombes."
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