Control four stepper motors in unison?

[Wes LeMarr]

I am trying to convert an old cam operated Brown & Sharp screw machine to CNC. I will need to control four ballscrews driven by stepper motors. I think I understand how to control a single stepper motor with a single controller, but the question is how do I control all four in unison? Any help will be appreciated.

[H500]

Connect each motor to a controllers. Connect the 4 controllers to a PC, running a program like mach3 or turbocnc.