Looking for a Depraz mouse.

Putting one of the X signals and one of the Y signals the CB lines makes sense, since IIRC you can generate an interrupt from those lines. Then the mouse driver can resposd to that interrupt by seeing which axis changed state and what the state of the other signal on that axis is (to determine direaction. IIRC, there's nothing special about lines PB4 or PB5, you can't use them as inputs to counters, or the shift register, or as interrupt lines, or.. Which seems to indciate that _if_ yuor mouse was designed to plug into a Beeb user port, then the drier had to poll the user port often enough to detect changes on these lines. Hmmm... [...] Unfortunately my ACW doesn't have mouse board at all, so my diagrams can't cover it. The serivce manual has not real technical info on the mouse at all, it's a boardswapper guide for that section (but has component-level repair info for the I/O processor (BBC B+ board), 32016 board and monitor. I thought the mouse interface was an Acorn design, so it's odd the schematic isn't included. I thinkl I read somewhere that the ACW mouse plugs into a DE9 connector on the back, which is then linked to the mouse interface PCB, which in turn plugs into the 1MHz bus (I think physically it's in the same side tray has the hard disk interface boards). I _asusme_ the signals on that DE9 are +5V, ground, 2 pairs of quadrature signals and 3 button signals. -tony