PROM Switching (Was PC war thread)

[Frederic Breitwieser]

Hey Joe,

>You guys and your software jokes!  You crack me up!  (Did any other
mechanical
>types understand it?  Uh, huh.  Me neither.)

That's okay, I'd be happy to translate:

If (mailing list member is using HTML rather than plain text)
then (smack them with a 20lb hammer)
Else (smile)

Any better? <Grin>

>Before you two get into a pissing contest to see who can piss higher up
the PC

Actually, I didn't take his response personally, and enjoyed the humor on
both sides.  He brought up valid points, as did I, and that's the spirit of
any group discussion.

>hook a laptop to a GM ecm directly to the eprom to develop the various
maps and
>flags for tuning a custom engine setup?  The idea is to avoid having to
pull and

There's a chip made by Dallas Semiconductor, which is an EPROM compatible
replace chip - except its static ram, has a 10 year lithium battery, and
about $6 instead of $1.

The issue would be, writing information to the chip while the GM computer
is reading it... which it does pretty much constantly while the ECM is
running its code, looking up data, etc.

Theoretically, it could be done, if the ECM was halted (turnd off, or put
into "sleep" mode, much like a notebook).

There is a product like this... I've seen them on the Grand National e-list
(you know, the black high-powered turbo Buick Regal?), where you can
install 4 EPROMS into this "black box", and select them on the fly.  This
allows the stock chip for sunday cruises, a mild chip for street light
games, a more radical chip for higher boost levels, and a fourth chip for
making coffee :).  Seriously though, there are products that do this, minus
the coffee joke.

>with data out of the laptop until the prom maps are nailed down, then burn
the
>prom from the file in the laptop.

With an embedded system I made a few years back, I used the Dallas chip I
mentioned, so I could reprogram it easily without having to pull the chip,
go up two flights of stairs, plug it in, re-program it, then go back
downstairs, plug it in, and find that my changes were worse.  The
application was an alarm system, but the theory is the same.

>reguire a separate board if a lead for each pin of the prom is required.

Eproms and EEPROMS have a Chip select pin, where as grounding this pin
enables the chip.  Ground one at a time, and you can run them in parallel
electronically, and only use one at a time.  This is how the aforementioned
device for the turbo regals work, with some circuitry to stabalize the chip
selection.

>And I'm sure some software is required.

More than likely :)

>Whatyathink?  This inquiring mechanical mind wants to know.

There's my thoughts, I'm sure others will chime in.  So Mr Mechanical, how
do I shove 4 valves per cyl on my Buick heads <Grin>.


Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/

1993 Supercharged Lincoln Continental
1989 HMMWV
2000 Buick-Powered Mid-Engined Sports Car