56D215 Stepper ( Calcomp)

I fancy using this stepper, but not getting very far reverse engineering the driver board . the stepper chips L6201 im OK with, the other IC S9312AD I am guessing to be a bespoke controller, the 20 pin connector seems to be mainly GND and power with only 8 signals , I think are phase , direction and current control. I may have to just start again removing the pcb and adding my own stuff to the 8 wires .
A Calcomp service engineer gave me some stuff when he got made redundant in the 90's .... but no schematics

I found a chinese datsheet for the S9312AD online, but my reader wont open it as the font is incorrect.
Unless your prepared to mess around for ages, and possibly blow it up allying the wrong voltages another driver is a good idea.
Do a google for easydriver, its a stepper driver module that comes on a little module pcb, there are versions that will microstep to 1/32 step, the only signals you need are step mode, clock and direction, current is set with a on board pot.