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

[Bill Lewis <wrl...@gmail.com>]

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. :-)
>
> Http://Goodall.com
>
>
> 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.
> >
> > Bill
> >
> > > 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:
> > > > > Bill,
> > > > >
> > > > > 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
> > > > > erasing.
> > > > >
> > > > > It seems that some cells take longer than others, and the later
> > > > > portions of the erasing time is spent clearing the recalcitrant bits.