My UniSite has a DIP-48 and a bunch of PLCC, SOIC, and a set of QFP ZIF sockets. What's more, I'll bet you could buy one for less than a simple "universal" programmer. They program nearly anything. A new one costs about $50k, but an old one can be had on ebaY for about $350 including all you need. That's a lot less than what I've had to pay from time to time for a small, portable, and very limited model.

If you look inside, you'd find a bunch of pin driver boards and a pretty large circuit board with CPU, lots of memory, and a floppy and even hard disk adapter.

The small, portable programmers I have attach to the PC via the parallel port or, in two cases, through an ISA adapter (yes, they're pretty old). They use PIA's (i8255 and MC6821's) to read/write the logic levels, and discrete circuits to drive the pins they believe should have power and gnd connections. In this, they're usually wrong, so they have to have adapters for some devices. Those adapters are costly and fragile, and typically absent when you need them. They're often "wrong" in either the resistor/capacitor values they carry, or in the pinout, and require modification, which is difficult and tedious, and they seldom support more than one device. These "portables" are portable in the sense that they fit in your briefcase, but then they require another briefcase to carry the adapters you need.

If you need ONE "universal" programmer, I'd look for a UniSite. If you want to build one, I'd read about PIN DRIVERS, as you need to put a low-impedance and clean power supply on at least one pin and low-impedance GND on another. Sadly, it's seldom the "corner" pins any longer.

RE