The Kempston mouse was a mouse interface for the ZX spectrum and compatables.
it uses an interface with two signals per direction 180 degrees out of phase to determine the direction the mouse is going in[quadrature encoding].
Note, The original Mice have a different pinout to either Amiga, Atari or Datel mice, so don't mix them up! In particular, plugging an Amiga or ST mouse into the original interface will fry the mouse as it puts +5v right into the output of one of the mouse comparators!
|64479||FBDF||xxxx x011 xx0x xxxx||X axis||00-FF Roll over at 0 and $FF|
|65503||FFDF||xxxx x111 xx0x xxxx||Y Axis||00-FF Roll over at 0 and $FF|
|64223||FADF||xxxx xx10 xx0x xxxx||Buttons||D0:Right D1:Left D2:Middle (Some compatables only)|
- black-ice contains full details including PCB pictures and a schematic.