replace an EPROM with an EEPROM?

[Chad Clendening]

I used a 28C256 ( 28 pin 32Kx8 EEPROM chip) in place of a 2764 in an ECM.  I was
lucky as the board had the unused pins of the 2764 pulled high ( /WE and the
highest 1 or 2 address lines of the 28C256.) I believe the only odd thing I did
was to load the program at 2 differant offsets to get it right.  This worked fine
once the offset was correct.  You shouldn't have to play with offsets if you are
using the same size of chips.  Just get the pinout correct when making the
adapter.

I did put ZIF sockets into this ECM as the original chips were soldered in.  No
more bending of leads.

Chad



David A. Cooley wrote:

> There may be problems...  there are CE and PGM on the 28256, Guess if you
> pulled it to reprogram, it would be a little easier than erasing a UV eprom.
>
> At 10:43 AM 1/31/99 +1100, you wrote:
> >
> >
> >>Pinouts are different... 27C256 is a 28 pin, 28256 is a 32 pin...
> >
> >
> >But electrically would it work?, an adaptor would be no prob really.
> >I assume the extra pins are for re-programming?.
> >I agree with Ted, this method would save so much time.
> >
> >>At 05:06 PM 1/29/99 -0500, you wrote:
> >>>Has anyone tried to replace an Eprom with and EEprom?
> >>>Specifically, Replace the 27c256 in a Memcal with a 28256?
> >>>Does anyone know if it would work?  or is the pinout somehow different?
> >>>The reason I'm interested in doing this is because it would be more
> >economical
> >>>and efficient.
> >>>
> >>>Also, what do people do about removing and replacing their Eproms from the
> >>>Memcals when reprogramming them?  Do you solder in ZIF sockets?
> >>>
> >>>I want to start lookin at and modifying my Memcal, but have never done any
> >of
> >>>this stuff before.
> >>>
> >>>Thanks,
> >>>Ted
> >>
> >>===========================================================
> >>           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
> >>     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
> >>       I am Pentium of Borg...division is futile...you will be
> >approximated.
> >>===========================================================
> >>
> >
>
> ===========================================================
>            David Cooley N5XMT           Internet: N5XMT at bellsouth.net
>      Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
>        I am Pentium of Borg...division is futile...you will be approximated.
> ===========================================================