A 4-axis interface with encoder counters, PWM generators and digital I/O. Connection to the computer is via the parallel port. The encoder counters can handle count rates up to ten megaHertz on each axis simultaneously. The PWM generators have a 25 ns granularity, so they can do 1/8 % resolution at 50 KHz (800 discrete pulse widths). At higher PWM frequencies the resolution is coarser in percentage terms, at lower frequencies it becomes finer. There are 16 optoisolated digital inputs, one is dedicated to the E-stop system. The rest can be used for home and limit switches, jog pendants, or whatever else is needed. There are sockets on the board to mount up to 8 solid state relays.