T Jackson "Your reference to the website incurred me to think you found this code rather than wrote it..."

You are right. I have copied this code directly off this website. That's why I am on this forum - because the website claims it works together with the circuit they provide, but I can't make that happen.

Having said that, I have found other sites where precisely the same circuit is used with similar code, so it seems that I am doing something wrong.

Mister-e - I can't make VA work either. I am not skilled in electronics, but expected to see a set of 6v steps if I put a probe on the output of this circuit and attached the ground to 0v. Instead, what I got was a sine wave. In fact, whatever I do, I seem to get a sine wave. The oscilliscope setup setup just seems to measure RMS or peak-to-peak - I can find no DC setting at all. When I turn the circuit on, the sine wave is interrupted by short pulses which decay to 0v rapidly, so if those are real I am failing to get a proper signal to the stepper coil, but since I can't even make the scope line jump up when I put 6v across the terminal I can't be sure that VA is working at all....