EPROM baking

Michael Zahorik m.zahorik at sbcglobal.net
Wed Dec 13 09:33:07 CST 2017

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 at classiccmp.org>
 To: dwight via cctalk <cctalk at 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...


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-bounces at classiccmp.org> on behalf of william degnan via cctalk <cctalk at 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 at 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

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