Eprom Emulation

[David A. Cooley]

At 06:51 PM 4/6/99 -0500, you wrote:
>Ludis touched on this previously, here's what he said about read timing:
>
>
>-------------------
>The P4's deselect the PROM for 120ns, but enable it for 360ns.  I don't
>how much of the 360 is lost due to data setup time.  OTOH, the C3's
>might not deselect the PROM at all between back to back accesses.  Which
>brings up the point - it might be good to prevent a bank switch between
>data read cycles of a "LDD $89AB".
>-------------------

Didn't catch this the first time it came through...
A couple things from personal experience with the C3 and P4...
On my Buick GN I made a board that had 2 proms on it and used a 4066 to
switch the CE line so you could select whichever chip's cal you wanted...
I used to use it constantly, switching back and forth under cruise, idle
and even a couple times at WOT.
There was never a hiccup.

I also had a 93 Jimmy withthe 200HP Vortec 4.3L V6 and a P4 pcm...
I had a 6 in 1 JET chip... it was basically a 27010 chip with 6 programs
burned into it (top 256K was empty).  The lower address lines went to where
the stock address lines did, and the data lines all went to the PCM.  to
switch programs, all you did was toggle one of the 3 higher address lines
to select the 128K bit block you wanted...  How about an Emulator that
follows similar lines?  
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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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