for two stepper motors using two L297 driver ICs. This circuit take control bits from computer parallel port or other I/O port with TTL signals
http://www.saunalahti.fi/~mikkolaa/images/hedelma_sch_3-6.jpg
http://www.interq.or.jp/japan/se-inoue/e_step.htm
allows you to drive up to two 4-phase unipolar stepper motors connected to the parallel port. includes driver hardware circuit diagram and circuit board design.
http://freshmeat.net/projects/step/
uses a servo potentiometer to provide the necessary drive pulses for a stepping motor
http://www.e-insite.net/ednmag/archives/1995/080395/16di3.htm
slewing control for stepper motors that you use in sophisticated applications, such as monochromator movements in optical experiments
http://www.e-insite.net/ednmag/archives/1997/031497/06DI_02.htm
can be adapted to be controlled by a computer
http://www.aaroncake.net/circuits/stepper.htm
control hardware and software examples.
http://eio.com/jasstep.htm
High accuracy RPM-measurement with 68HC11.
http://space.tin.it/computer/lorgler/sw-step.htm