EPROM Emulator Proposal

[David A. Cooley]

At 05:28 AM 4/7/99 -0800, you wrote:

>Anyway, here is an emulator proposal based on the prior discussion.  I
>did some ruthless cutting of features and expandability (indicated with
>a *).  I propose the use of a single dual-port SRAM (from Cypress or
>IDT) and a 40/44 pin PIC microcontroller to load this RAM.  A battery
>back up will keep the SRAM alive.  This allows an ECM to boot from the
>DPRAM immediately upon power-up.  The whole emulator circuit board
>should be small enough to fit inside a '165/'727/'730/'749/'808 ECM.
>

Here's a fly to add in to the ointment...
How about a couple Dallas Semi DS1230Y NVrams that are updated at the PIC's
leisure when it's not updating the DPRAM.  When the unit is powered back on
(IE restarting the car), the NVrams are read into the DPRAM so a battery
backup isn't needed... the othe roption is EEPROM instead of DPRAM



>The ECM's A0-A15, D0-D7, ~CS, and ~OE connect directly to one side of
>the DPRAM.  The address lines are shifted up by one so that the DPRAM A0
>can be used for the bank select.
>

Shouldn't that be A15 for bank select?


>Is there enough interest for me to draw up a schematic in a few days? 
>Someone else will need to draw up the power supply circuitry.  Following
>that, circuit board artwork will be needed (David?).  If we decide to
>proceed with this design, I should have time to write some code for the
>PIC in a month or two.  Right now my top priority is assembling an engine.
>

I'd be willing to do the board layout... I actually enjoy it!


In the meantime, I'd still like to go ahead with the beta of the cheapo
emulator that was posted by Mike Pitts (I think...)
It's hardware allows for one byte changes, but the software needs re-done
to support that... Boards will be about the same cost ($50 each for beta,
25-30 each for qty 10 in production).

I have one check so far for the beta's...
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           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.
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