For designing a servo amp: search Google with keywords "IR2110, H-bridge, PWM etc.".
Software for PC: search for "Yeager CNC Pro, TurboCNC, Linux EMC etc.".
Rutex has some nice chips and servo amps/controllers that work well with common PC software that are designed for stepper control. Servos are smoother and cheaper than servos, that's why the tendency is nowadays to use servo controllers with step/dir pulse interface for position control.
You'll need for example:
- A counter that counts the step/dir signals from LPT
- A counter that counts the motor's encoder pulses
- An adder that subtracts the latter from the former
- A DAC for analogue output: 0...10 volts: 5 volts means standstill, or -10...+10 volts: 0 volts means standstill.
- A PWM generator and PID filter: voltage in, PWM out. In one system 50% PWM signal to servo amp results in standstill; less than 50% and the motor runs backwards, more than 50% and the motor runs forward.
It's not very complicated, but perhaps I presented it in a complicated manner...
Hobbie