Troublesome Eprom

[Ludis Langens]

Shannen Durphey wrote:
> 
> I've got a Delco marked and numbered Eprom here.  It came from a '165,
> so I'd expect it to be a 16K chip, but I can't seem to program it.
> The numbers are as follows:
>
> 40581

That's a new one.  (A thought.  Dig through pile of MEMCALs.)  Nope, not
a new one.  I've got a MEMCAL with a 40581 EPROM.  It came from a '165
used with an '86 1.8 TBI.  Perhaps this old number is an NMOS EPROM
and/or one needing a 21 or 25 volt programming voltage.

Alternately, I've encountered many 16Kbyte EPROMs which are really 32K
EPROMs.  One the front they've been marked with the GM part number for a
27C128.  On the back they say 27C256.  These are likely 27C256's with a
bad bit in the lower half.  The chip industry has been unloading their
rejects this way since forever.  (A 27C256 will work just fine in a
socket meant for a 27C128.)

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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