Recently, Somebody Somewhere wrote these words
> I suggest you quit messing around with check sums and get to work. ;-)
Unfortunately, that's a no can do. I need the checksum of that PAL
to ever get a replacement from these guys in the future. This is
to fix a 1999 version of a machine sold from 1992 - 1999. Those
guys are 2 model revisions on.
> Who was it that offered the defination of insanity as repeating the
> same experiement and expecting different results?
> Your boolean equations, and therefore your check sums, must be right
> or couldn't get it to boot with one of the old PALs. Ordinarly PAL
> programmers automaticly checksum so if there was a problem I think the
> programmer would say so.
Maybe my explanation lacked. One of my PALs has a pin blown (Pin
23) The manufacturers won't replace the one, they feel I should replace
the four. They can't supply me correct PALs. Here's where the
checksums of mine become relevant. They haven't a clue really, and
I have the only working part for one of them.
> Your symtoms suggest you are running ripple logic with faster PALs.
> If so, you are trying to fix a bad design rather than a simple
> compoent failure. In short a hard road to hoe.
I Agree totally - fixing a bad design is what I am trying to do.
They do have 74BCT (Texas bus logic) all over the place.
> Here is where I'd start.
> 1. Check your power supply. Make sure it is absolutly clean. Faster
> devices are more sucesptable to noise. Add bypass caps if you
> don't see them on the PALS. Check out the power supply
> electrolytics.
The power supply isn't perfect, but it's reasonably good. I'll add
bypass. But this fault developed with heat (Cold everything worked
- warm it failed) and then became permanent. I am not thinking of
power supply issues, even thou that has had a ressurection.
> 2. See if you can find low power equivalents for your PALs. Quarter
> power versions are ideal. That does not mean switch to CMOS. The
> idea of using low power bipolar versions is they are much slower
> devices. It's not to save power. Remember speed kills.
>
I can't choose the PALs they program! They won't give me the code.
My guess is they are programming in the wrong files. I have reason
to believe this (They hunted for weeks and then came up with these).
So I'm about proving they have the wrong parts and pointing them
at the right ones.
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
Fat City Hosting, San Diego, California -- http://www.fatcity.com
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