This is the driver board i designed for the stepper motors on my milling machine.
It is based on the Atmel AT89s8252 and i wrote all code in assembly.
It communicates via RS232 with the computer.
It received data in this way: Motor nr, Direction, Speed, Amount of steps.
The Atmel gives a signal back when its done to receive next commands.
Very simple and no backfeed is used. Thanks to the very strong motors which dont make any mis-steps.

The motor coils take 4 amps each at 4 volt. The power comes from a computer powersupply.
There is no need for any cooling of this driver board. It runs a little hot but thats all. very efficient.

On the computer i had to write my own cnc program in delphi.
Below you can see the setup which i still use up today.
The whole cnc conversion i did up till now took me about a 1 and a half week.
Offcourse its not finished, i still need to make the Y axis mount and i need feedback from the table of the actual possition