[OT] 1950's WITCH computer running again

[Tim Watts]

I expect someone is Russia still makes them...

[Jim K]

Spllllllllthththththththt off, misery

Jim K

[Mike Tomlinson]

En el artículo , Tim Watts escribió:

I did some digging. Dekatrons are still available in Russia, but with a different base, so need an adapter. There's also a surprising amount of the originals on fleabay.

The Dekatrons used by WITCH are the GC10A and GC10B, the Russian compatible is OG-4.

From the restoration blog:

"I am looking at the possibility of using the more readily available Russian OG-4 Dekatrons as a direct replacement for the GC10A. OG-4's seem more similar to GC10A than GC10B (low strike voltage) although they have a different pin-out. No problem - I adapted the base of an OG-4 with epoxy and an octal base from some unknown broken valve. An advantageouas side-effect to this is that the OG-4 is now slightly longer (but still not as long as a GC10A!)"

This is the blog of the restoration, up to May this year. They make fascinating reading. I'm posting the direct links are they're hard to find from the home page.

doesn't seem to be an entry for 2011.

[Jules Richardson]

The critical thing is that Colossus isn't a stored-program machine (which upsets some of the purists who therefore don't class it a a computer), whereas Witch is.

The rebuild nature of Colossus doesn't seem to generally bother people IME - it's seen as a faithful-enough system that it's the best that can be done under the circumstances (there might be a chance that GCHQ have one or two originals in one of those warehouses like at the end of Indiana Jones, but after so long it's probably unlikely ;)

I did take the trouble to ask, and the majority of Colossus is fabricated from GPO parts that are identical to what the originals used - although they came out of phone exchanges which were much later. There are some modern resisors and capacitors in there, and the wiring is all modern PVC; the originals would have had cotton-covered enamelled wire, but apparently that stuff isn't particularly pleasant (particularly when hauled out of rat-infested old exchanges :-)

cheers

Jules

[Grimly Curmudgeon]

Good grief, is it 1994 again?