The UK's National Museum of Computing in Bletchley Park did a rebuild.[1]
But not much detail is given in the video. Anybody know of a schematic?
Turing's paper was quoted in Cryptologia, but that is paywalled now.
The 7-tube "combiner" is clearly analog. The key generator seems to be three multivibrators phase-locked with relatively prime ratios. That's cute. It's a pseudo-congruential random number generator in the analog domain.
This exploits the effect that oscillators that are weakly linked will tend to come into sync.
Not necessarily at 1:1; you can sync at various ratios, with difficulty. Must have been a pain to get to work reliably. I'd like to see the schematics.
With phase-locked loops and counters this would be easy; that's how modern radio tuners work. Not easy to make reliable with 1940s technology. Getting things to sync up was a huge headache until the 1970s.
The 7-tube "combiner" is clearly analog. The key generator seems to be three multivibrators phase-locked with relatively prime ratios. That's cute. It's a pseudo-congruential random number generator in the analog domain.
This exploits the effect that oscillators that are weakly linked will tend to come into sync. Not necessarily at 1:1; you can sync at various ratios, with difficulty. Must have been a pain to get to work reliably. I'd like to see the schematics.
With phase-locked loops and counters this would be easy; that's how modern radio tuners work. Not easy to make reliable with 1940s technology. Getting things to sync up was a huge headache until the 1970s.
[1] https://www.hmgcc.gov.uk/news/turing-s-rebuilt-delilah-machi...