Are you trying to program "classic" 2732, i.e. a UV-erasable EPROM?
Yes, that's correct. I use a specialized UV-lamp (a small fluorescent tube) I've had since the early 80s for erasing. Still works fine. Takes me about 10 minutes to completely erase a chip.
The particular EPROM I'm trying to program now is an Intel D2732A-3.
Correct me if I'm wrong, but don't these require 25V programming voltage, and isn't the TL866 known to be incapable of that? Some users have reported success at 21V programming voltage, although that is out of spec for these old EPROMs, I believe.
http://www.insentricity.com/a.cl/196/ItsNotStupidItsEnhanced
You nailed it!
That solved my entire problem. I did actually look into it (because on the EPROM it says "PGM AT 21V"), but I believe I've used 12.5V with other EPROMs so I found this a little strange.
So I found its
datasheet (it actually just says "2732A" but I suppose it's the same thing). I often find datasheets complicated to read and I must have misunderstood something because it says "
Vpp supply voltage with respect to ground during programming: -0.3 to +22V" but re-reading the document this was under "absolute maximum ratings" and elsewhere I see that it says "
In the program mode the OE/Vpp input is pulsed from a TTL level to 21V" which I guess is just a detailed technical way of saying that its programming voltage is 21V
Fortunately the TL866 software allows me to use a maximum of 21V (you're right about the absence of 25V) so all I did was:
1) Select the correct EPROM type (24-pin 2732A)
2) change the "
VPP voltage" to
21V (I think it was at 12.5V by default)
3) load the 8K (2764) BIN file
4) burn (program) the EPROM
3 seconds later... bingo! no error message and everything worked as it should. I even tried it out in the drum machine. Sounds great!
Such a simple solution. It sure would have helped with properly translated software, but I guess you get what you pay for
Nice blog link. Brings back memories with the Apple II. It was mostly 2716 back then and I even had an EPROM programmer for it! I think it took 2716, 2732 and 2764 chips.
So, since there apparently was no programming voltage standard back then I assume we need to look up every single EPROM's datasheet before burning (or we might end up literally burning them out!). It's probably a good idea to write the programming voltage with a white marker on each chip.
Oh, a final question: does anyone know where you can get low profile ZIF sockets (for quickly/easily exchanging EPROMs)? It should extend no more than 10mm (absolutely maximum 12mm) from the PCB and have 28 pins. They sell them at
the DMX files for US$ 12.50 each, but apart from the initial high cost there's the usually very high shipping cost from the United States which doesn't justify most purchases.
Does anyone recognize that black low-profile ZIF socket in the link and know if anything similar at lower cost is available? Of course it has to be of reasonably good quality (for home use) although there's no need for "industrial quality" for millions of repeated insertions at a premium price.