[Diy_efi] NVRAM chip for a 1986 GM odometer?

[Gregg Eshelman]

--- Torbj?rn Forsman <torbjorn.forsman at gengas.nu>
wrote:

> Indeed, GI made some obscure eeproms during the late
> 70's and 80's. One 
> common type was the ER1400, which was mainly used
> for saving tuning data 
> in televisions, car radios etc. It has a rudimentary
> serial interface, 
> definitely not so sophisticated and user-friendly as
> the SPI/Microwire 
> or I2C interfaces of more recent eeproms.
> One common (and awkward) thing about old eeproms is
> that they often use 
> strange supply voltages and logic levels. I am not
> exactly sure, but i 
> think that the ER1400 needs +5 V, -40 V and possibly
> one more voltage 
> too. The logic levels are 0 V and -9 V.

I've found what seems to be a compatable chip, the
Mitsubishi M58653P, and I found it for only $8.99
rather than the almost $90 ripoff price Galco wants
for a GI ER1451.

http://www.acme-sales.net/acmecart/html/main/portal.php?country=USA&p_id=M58653P

ACME doesn't have the GI chip.

Comparing datasheets for the two, the only difference
seems to be that pin 4 is a ground on the GI chip but
is not connected on the Mitsubishi. 


 
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