Semi-Junkbox 2708 Programmer

I got in a bunch of good-looking Intel 76/77 date coded gold/ceramic 2708 EPROMs, which I wanted to use in my projects. Unfortunately, the programmer I use can't program them (not too surprising, because these early chips used +12 and -5 as well as +5, and had strange programming algorithms) without an adapter that costs almost twice what the programmer itself cost! So, I embarked on building a 2708 programmer.

The programmer in Figure 1 is more of a "copier", although when combined with my 2716 emulator, it works more like a commercial programmer. You put in a 2716 in the left socket, select the high or low half of the 2716 to copy, press a button, and about two minutes later, your 2708 is programmed. It uses a charge pump made of a 555 for the Vpp, and a Ubicom flash microcontroller handles the logic, with code written (sloppily, but, hey, it works) in C. Because I try to save money on tools that will see infrequent use, I used epoxy putty for a strain relief on the +9 volt wall wart wiring.

With some modifications, I think this might be able to program 2704's or TMS 2716's, but I don't have any of these.

Figure 1. 2716-2708 Copier/Programmer