Alec, I've seen several good solutions mentioned but another you might
consider is the CD4067 16 channel analog multiplexer. It would require five
lines though. Four for address and one for data. It also has an enable input
so you could cascade them for more switches.

   - Tom

At 10:43 AM 8/20/97 PST, you wrote:
>     From:    Alec Myers <Alec@SHRUBBERY.DEMON.CO.UK>
>
>     Does any know a cute way of reading three BCD thumbwheels that uses
>     less than
>             i)      Twelve i/o pins
>             ii)     Seven pins and 12 diodes?
>