GCHQ celebrates 80 years of Colossus

Today we have released a series of rare and never-before-seen images of Colossus, in celebration of the 80th anniversary of the code-breaking computer that played a pivotal role in the Second World War effort.
The release of these images sheds new light on the genesis and workings of Colossus, which was over two metres tall and considered by many to be the first ever digital computer.


Interesting to see a few photos of Colossus from the 1960s.
(If you look at the filenames, they say 1963. There are also a few details in the photos, like the console typewriter or instruments in the background, hinting at this period.)

I wonder what is meant by the “I. C. machines” which are held out as being hopefully capable of operating at adequate speed. From context it might possibly be the Flowers machine. But what is I and C?

IC probably stands for Index of Coincidence.

The German wikipedia also mentions an IC machine here

60s computer: 10 machines were built between 1943 and 1945. (Wiki). According the article, 8 were destroyed. The remaining also used in the 60s. Which of the 10 survived and if it’s an original one pictured or a rebuilt might be questioned. The photo is just from the 60s not the computer. Otherwise it would not make sense (WWII).

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Aha! Thank you very much!

That led me to a very interesting paper
Gladwin, L. A. (2007). Bulldozer: A Cribless Rapid Analytical Machine (RAM) Solution to Enigma and its Variations. Cryptologia, 31(4), 305–315. doi:10.1080/01611190701506022

(Which I see now on the German Wikipedia page you linked…)