Computer in 1900

[Gavin Melville]

Hi, 

> Or, for example, solid-state diodes: the discovery may have 
> been made in 1874, but in the early 1900s the only thing 
> actually available (TMK) was the cat's whisker (a tad 
> finicky) - forget about building anything utilising more than 
> a couple of them.

Modern knowledge can help there of course -- I'm allowed to know why
they weren't reliable.  The trick they used in WW2 about setting them in
wax inside a ceramic tube improved shock resistence and general
stability greatly.   It did, of course, also allow them to be changed
quickly :-)

> Then there's achieving a stable power supply.

Same thing here.  Feedback can do wonders, even if the feedback is to
the primary, and done with a magnetic amplifier.

> ..so, depends on where you want to draw the line between 
> concept and practice.

This is really a question of resources, and while finite, are
substantial.   

> The principles/theory of digital systems implementation may 
> be straighforward, the practical reality when dealing with 
> unreliable/variable components isn't so (including tubes); in 
> particular if you don't have some heavily-non-linear device 
> to base your basic gate design around. In 1900 there was very 
> little in the electrical domain that was reliable or 
> consistent for the purposes being discussed.

This is why the interest in magnetic logic -- the idea works, well
enough to build a mainframe with it and the material was available in
1900.   The non-linear bit may, however be the killer, or in the case of
magnetic logic, temperature may be the killer.   We have basic gates
working, but need some gain to cascade them, hence the current work on
magnetic amplifiers.