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Re: [N8VEM-S100:608] Re: S-100 8086 Up and Running

In this case the ROM is a gigantic lookup table.
Can't program around it.

I've erased and programmed that chip half a dozen times.
Never had an erase problem before.  It was "used" though
when I got it.

On 12/27/2011 4:30 PM, Douglas Goodall wrote:
Yea, you have a fifty-fifty chance of the prom being ok even if your data load takes up the entire prom. You can always program around it. :-)


On Dec 27, 2011, at 11:35 AM, Bill Lewis<wrl...@gmail.com>  wrote:

On 12/27/2011 2:31 PM, Douglas Goodall wrote:
Is that bit stuck in every byte?

No, just that one bit in the entire EPROM.

Luckily the current data load has that bit clear, so
I haven't thrown it out yet.


On Dec 27, 2011, at 10:33 AM, Bill Lewis<wrl...@gmail.com>   wrote:

I have a TMS 27C512 right now that has a stuck bit that
won't erase.

I put the thing in the eraser for 15 minutes.
Blank check, and all ones except that bit.

Back in for another 15.  No change.

And another 20 minutes.  No change.

Must be kaput.

On 12/27/2011 10:28 AM, Douglas Goodall wrote:

Around the same time, I was working at a startup using quite a few
2716's. We were having quite a lot of trouble with them.

I came up with a technique for doing quality assurance on them
based on checking the content of the EPROM over time while

It seems that some cells take longer than others, and the later
portions of the erasing time is spent clearing the recalcitrant bits.