The only "baking" I've heard about with EPROMs was *annealing* on the original prototypes from Intel. I want to say that was before they figured out UV erasure and were zapping the things with X-rays for erasure. You won't be doing any EPROM annealing in a home oven :)
It's been my experience that usually defective 2708s or 2716s will fail to program, rather than fail to erase. Be aware that some of these old EPROMs take quite a while to erase. Newer stuff like 2764s are usually done in around 15 minutes with my old UV eraser, but I've had to run old 2708s and 1702s for much longer, 30+ minutes usually. I think my eraser uses a 15W lamp, for reference. Try programming all zeros and see if it'll take. If it does, try and erase them. If you start seeing some bits flip to one but not all of them, increase exposure time. If you get up around an hour and you still have zeros in some positions, the EPROM is likely bad. If you're debugging or developing on something, I wouldn't bother messing around with potentially bad EPROMs, especially 2716s since those are still pretty available. You can also drop a 2816 EEPROM in there (there are other pin-compatible EEPROMs, SEEQ had one, there may be others). And, of course, be aware that Texas Instruments' 2716 is its own thing and not compatible with the common 5V-only 2716s. They called their Intel 2716 compatible a 2516. Thanks, Jonathan On Wed, Dec 13, 2017 at 10:33 AM, Michael Zahorik via cctalk < cctalk@classiccmp.org> wrote: > My homemade 8080 CPM machine used a number of 2708 and 2716 EPROMs. that > was 40 years ago. This machine is still running and I use it, but since I > had trouble with the EPROMs, I switched to EEPROMs. I would also be > interested in hearing about whether or not baking would work and how to do > the baking, exactly. I have a bunch of old EPROMs, that I figured were > dead, but maybe not? Mike Zahorik > > > From: Holm Tiffe via cctalk <cctalk@classiccmp.org> > To: dwight via cctalk <cctalk@classiccmp.org> > Sent: Wednesday, December 13, 2017 9:17 AM > Subject: Re: EPROM baking > > > Hmm..I've read about that baking in conjunction with 1702A too..but > don't remember the source of that discussion. I know that ppl suggested > it for proms that would'nt program correctly... > > Regards, > Holm > > dwight via cctalk wrote: > > > When I was at Intel, years ago, I recall the baking was only to repair > the retention of the EPROMs. It was not to fix random failures. > > > > It sounds like your EPROMs have various failures that wouldn't be helped > by baking. > > > > Each time the EPROM is programmed, there is a slight increase in the > leakage of the floating gate. This was typical after thousands of > program/erase cycles. Baking them repaired the damage to the insulating > layer that was damaged. > > > > Dwight > > > > > > ________________________________ > > From: cctalk <cctalk-boun...@classiccmp.org> on behalf of william > degnan via cctalk <cctalk@classiccmp.org> > > Sent: Wednesday, December 13, 2017 6:18:16 AM > > To: Mark G Thomas; General Discussion: On-Topic and Off-Topic Posts > > Subject: Re: EPROM baking > > > > On Wed, Dec 13, 2017 at 9:08 AM, Mark G Thomas via cctalk < > > cctalk@classiccmp.org> wrote: > > > > > Hi, > > > > > > I am working on several projects requiring 2708 and 2716 EPROMs, and > > > am finding some of my chips will not erase, and some will not take > > > a program. I've also learned more in the past week than I wanted > > > to know about repairing Data-I/O 29a/b programmers. > > > > > > I vaguely remember in the 1990s baking such EPROMs in the oven, but > > > I do not remember temperature or time. I was surprised that Google > > > didn't turn up anything useful with this info. > > > > > > I'm sure someone here will have some notes on EPROM baking. > > > > > > Mark > > > > > > > > > > > > > Mark, > > > > If this is an issue about reviving bad eproms? I assume you have tried > the > > regular stuff. > > > > What process are you using now to erase 2708/16's? I have a simple > eraser > > unit and it seems to always work. Some eproms go bad but I never have > > issues with erasing them. My point is that maybe you need a better prom > > eraser unit. I would avoid baking them until you have exhausted other > > options. Not sure what others think. This topic has come up before > here, > > about putting them outside and all that. The erasers are all over ebay, > > and the hardware store is full of the correct types of lighting, why not > > make a box that will do the job? I assume there is more to it that > > simply erasing them. > > > > > > Bill > > -- > Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, > Freiberger Straße 42, 09600 Oberschöna, USt-Id: DE253710583 > i...@tsht.de Fax +49 3731 74200 Tel +49 3731 74222 Mobil: 0172 8790 741 > > > > >
