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?

     ---

     Try a latch and a shift register:  3 or maybe 4 pins.

     Tristate buffers on each thumbwheel: 2 for address, 4 for BCD value,
     and since you are using 3 switches the 4th binary state on the address
     pins allows you to reuse the 4 BCD address lines for something else.

     Nothing else springs to mind right now.

     Andy #2