>Now, I would like expand the concept to be able to drive five (or
>even six) stepper motors off of a single processor.  I however, don't
>have enough available pins to control each motor directly.

That's easy!
Use the ULN2003 open-colletcor driver to control the phases.  Used diodes
between each stepper (anode) and the ULN2003 outputs (cathode) to isolate the
motors from each other.  Now use one high-side driver per motor to select it for
stepping.  Note that you can only move one motor at a time and you won't have
holding torque when another motor is selected.

- Mark Sullivan -