need help Programming '165 Memcal

[Ludis Langens]

Craig Marcho wrote:
> 
> I had
> another new GM chip so on a hunch I read it as a 256 and it had the code in
> there twice, so I'm guessing that the new chips were 256k eproms.

Seeing the code twice almost gaurantees that it is a 27128 type chip. 
Usually on the 27256 type chips holding a 16KByte image, the image is in
the upper half, and the lower half is all FFs except for the 3rd through
6th bytes.  Those bytes hold the sequence number.  GM seems to program
this number into both halves of the chip.

> I have no clue what these chips
> are, or what voltage they should be programmed.
>
> Here's a picture of two of them... the newer memcal is on the left...
> 
> http://home.flash.net/~marcho/twochips.jpg

Try programming the new one on the left (with the 9914 date code) at the
lowest voltage considering it is probably the latest technology - try
the 27C128A or 27C256A settings.  BTW, it's a NatSemi chip.

The old one on the right is probably a 27256 of some type.  All the
chips I've run across with the writing turned 90 degrees and with the
vendor code of 5012 (Intel) seem to be 27*256 chips.

What are the original BCCs of these two MEMCALs?  (Just looking for data
to add to calxref.html.)

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