Computer in 1900, was RE: Oldest operational computer was Re: cctalk Digest, Vol 54, Issue

William Donzelli wdonzelli at
Fri Feb 15 09:48:12 CST 2008

>  Why do you say 'very hard'?  I'm not sure when the relay was invented, but I
>  suspect it was way before 1901, given that the concept of an electromagnet was
>  so much earlier.

By 1901 relays were common items. Western Union did much of the
perfection in the mid/late 1800s.

>  I seem to recall that this was about the biggest problem in getting Colossus
>  to work in the 1940s; the technology for doing the optical detection of the
>  tape data just wasn't really 'there' yet, not at any speed. I think the
>  maximum they managed to get was around 8KHz, but it wasn't particularly
>  reliable (I think 5KHz was the norm, and it took an awful lot of initial
>  effort to get that working properly).

I am not sure what the photocells of 1920 were up to, but by 1940 they
were not half bad, with so many being used for FAX service. 8 KHz may
be about right for off the shelf tubes.


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