From: Mike Naberezny (mike_at_naberezny.com)
Date: 2008-09-18 19:03:54
Marko Mäkelä wrote:
> And some guys successfully replaced some PLA with an EPROM;
> a small wonder, because EPROMs have much longer access time than the
> signal propagation time in the PLA.
My 8296D had a bad PLA in UE5. I recently replaced it with an EPROM using a
small adapter: http://mikenaberezny.com/projects/pla-eprom/
The EPROM that I used is an AM27C512-45 (45ns) from AMD. I compared the
propagation delay table on its datasheet against the datasheet for the
Signetics 82S100.
Chip Enable to Output on the 82S100 is typically 15ns, max 40ns. The
AM27C512-45 datasheet only gives max, 45ns.
Input to Output on the 82S100 is typically 35ns, max 80ns. Address to Output
on the AM27C512-45 datasheet only gives max, 45ns.
Of course, I do agree that any old EPROM is probably not suitable. I think
the AM27C512-45 is a viable replacement based on this data. The computer
works well with it installed.
Regards,
Mike
--
Mike Naberezny (mike@naberezny.com) http://6502.org
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