Very cool! A modern analogue might be LinuxCNC, which runs on old PCs in a realtime manner, generating pulses and sending them out the parallel port, or sending commands over ethernet to a dedicated step generator board for ultra accurate timing. What's old is new again!
I wanted to check it out at some point though I'm a little scared about the ability of Linux to pulse step and direction with the same precision of a 15 year old DOS setup that has no background tasks and just hits that timer interrupt with very predictable result... The motion generation capabilities of TurboCNC are pretty basic though.
I'll go through my saved links tonight. I remember it was a bit of a cludgy operation, like all things new+Linux, but after I got everything setup it all worked as expected.