Pin drivers are circuits that can supply current in either direction, i.e. they can both source and sink considerable amounts of current. The role of the FPGA is primarily to function as a crosspoint switch, routing signals and controls to the appropriate pin drivers as appropriate for each IC to be programmed.

If you want merely to program two device types, your programmer is hardly "universal." You'll find that FPGA's are VERY costly, as are the pin drivers. That's why REAL universal programmers are not inexpensive. If you intend to program just a few devices, e.g. a selection of 805x-type MCU's, your main problem will be finding out how to do it.

If you want to program the tens of thousands of programmable parts that are handled by a "universal" programmer, your first task is to be able to source and sink, say, 500 mA to each and every pin of every device site that you will support. Your second task will be controlling the pin driver with which you intend to do that.

You'll find that challenging, I'm sure.

RE