[bojan]

Alistair,
I had a bad experience with mouse electronics.. the serial interface part and driver.
Nothing wrong with it per se, but these days it is hard to find adequate mouse drivers for DOS (no acceleration and so on).
Also, it seems there is a problem with handling mouse interrupts within the Bartel's software, resulting in the current position not updated properly while in tracking mode ((for example, if the scope was pushed unintentionally while tracking, the software would try to correct this by moving the telescope back to original position, but because the mouse driver was not working OK, sometimes - not always - it would overshoot, even 2x.. and the current position would be lost)
However, all those troubles went away when I switched to Ek's box interface.