You'll need three supervoltages, easily created from a single switchable ~27 volt DC supply in order to program 8748/49. IIRC, they require 25 volts for Vpp, and a one or two others close to that, but only a diode or two away from 28, and you can probably adjust the 28 to make the others "close enough". I used some sort of high-voltage display driver to control the base of the Vpp transistor (it has to handle a moderate current) which my high-voltage driver, a VF driver, IIRC, to build a programmer once. An OC driver and a PNP would probably work, but, today, low-voltage PFET's are much more available than they were in the '70's.

It's easy to switch down a 5-volt supply from that ~27 volts, too, using one of those "simple-switchers" that you can order as a sample from NSC.

RE