EPROM Eraser not erasing New EPROM

[Roger Heflin]

On Fri, 14 Apr 2000, 93 Formula wrote:

> >From: Roger Heflin  <rah at horizon.hit.net>
> >That sounds like the right procedure.    The black part is plugged
> >into the socket correctly and tight?
> >
> I've been leaving the modified IDC plug right on the memcal and just 
> slipping the ends into the ZIF socet for the programmer. I didnt really trim 
> the ends so they are still about 1.5" long but I dont think that is a 
> problem since I was able to read in the prom with no problem.
> >If you destroy the eprom don't worry, the eprom's are about $2-$5
> >each, it is the carriers and that other chip that are expensive.
> >Removing it and reinstalling a new one will be a pain that it should
> >not be that bad.
> 
> Does the chip need a break time between the eraser and the programmer to be 
> checked? I've just been moving it from one to the other.
> What are my chances of it working to dump the file to the chip without the 
> FFs appearing first? Zip?
> Jeff

No break time needed, I have taken mine straight from the eraser to
the programmer.   Are you putting the tape back on the eprom before
you are reading it?   I don't know if having light going into the
window will give odd bit readings or not, but it might.

If the byte(s) you want to change are set to FF, then you changes are
pretty good, if they are the changes are pretty bad.

Did you read t he chip before you started erasing it?   If so, read it
again, and save it in a different file, then dump both chips with a
hex dump program to a file, and use the diff command against it.   All
of these special commands are add-on dos command line like commands,
if you don't have them, send me both bins and I will process them, and
if you want I will send you the programs I used.   If you do this you
will be able to see how many bytes have been erased and that should
give some idea of what is going on.

If you have a digital camara you might want to take some pictures of
the various steps you go through and put them on the web and send me a
link and I will see if that helps with figuring out what is going on.

				Roger

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