StepmasterNC
The Stepmaster controller is simply 4 stepper motor divers with no other controls. Only the step and direction pins are connected direct to the parallel port connector, so no opto-isolation. Channels are hard wired for 1/8th stepping but as yet we have not identified if the step pulse should be +ve or -ve. 2uS +ve pulses seem to be working fine. Power is from a 24V laptop style power pack.
| Step | Direction | Notes | |
| X | 2 | 3 | |
| Y | 4 | 5 | |
| Z | 6 | 7 | |
| A | 8 | 9 |
Unit was supplied with locking mini-din plugs.
Taig Micromill Mach3 configuration file - 
Other variants
We have been supplied a copy of the manual for a 3 axis Sop-1 StepmasterNC board. 
We understand it also covers the Sop-2 but some confirmation on that would be nice.
There are a number of other StepmasterNC products that we are aware of but have no more details. Any other material that is available would be welcome to help people who are now picking up this kit on the second hand market.