Get a copy of "Omega Race Position Encoder" from the spies web page
It is a very nice description of building an optical encoder with
a little EPROM/latch state machine that does the quadrature decoding
and bit scrambling.
I should have the rest of the encoder figured out later today, so
I'll have the full decoding table then.
Turns out that an 8 way encoding works ok, and it's fast enough
that you could probably play the game with it using 'rotate left,
rotate right' buttons.
