Date   : Fri, 18 Jan 2013 17:38:45 +0000
From   : public@... (Daniel Beardsmore)
Subject: BBC Micro keyswitches

On 18/01/2013 15:11, Rick Murray wrote:
> My A310 has a keyboard like that - it's like little circles of tin foil
on sponge pads under the keys ...

That's the description of a switch type called "foam and foil" and it's 
a cheap capacitive system. It was a popular approach back in the day. Capacitive 
is mostly dead, but Topre still manufacture rubber dome capacitive keyboards,
which are expensive and very pleasant. PFU also sell keyboards with Topre
switches, the Happy Hacking Keyboard Professional line.

Conductive keyboards typically have rubber domes with carbon-coated ceiling
pads, placed over a PCB or--more typically--a single membrane sheet. The
Mitsumi variant of the Apple Keyboard II used sliders with large rubber feet
on them:

http://deskthority.net/wiki/Apple_Keyboard_II

The BBC Master 128 on the other hand used both mechanical switches (panda-coloured
Fujitsus, it appears) and Cherry MY switches:

http://deskthority.net/wiki/Cherry_MY

I shall update that page, as the authors to date were not aware of Cherry
MY switches being used on anything except Cherry G81-series boards.