I have been trying to run the stepper motor of a floppy drive(without removing it from the drive). I have given the appropriate 12v, ground and 5v to the power connector. Then I have grounded pins 12 and 16 from the floppy drive, this makes the spindle motor run. But when I ground 18 and give pulses to pin 20 by interfacing it with the PC's parallel port, the stepper motor doesn't run.
Kindly help me out.