Thanks Hood,
I have hooked up step drives many times, but have forgotten the exact wiring. I never had to add 5 volts. I am using Chinese drivers with 4 signal inputs (step-/+, dir -/+) plus 2 enable inputs.
I'm wondering whether the trouble I am having is from the old computer I am using that has a DB25 parallel port. I may retrieve the old tower desktop computer from the attic, and try that.