new paper

[Dave Zug]

Sure thing!. Thanks to Lyndon (Programmer) for getting my brain working to
actually write things down.

People have modified code before usually the "big guys" have a complete
disassembly and simply put their code mods in and re-assemble. My patch was
fairly small and I did not have a disassembled version and besides showing
the dual spark table thing, It shows a technique for simple Assembly code
patches without a using a compiler.  Of coarse a certain degree of assembly
programming understanding is needed. One thing about patching this way
verses the assembler way is that all the ECM-tools (GMEPro etc) will still
work using this patch method. An assembler will "bump" code but as long as
your DATA area is not moved you're okay. Be careful, the 730 and 727 have
DATA areas before and AFTER the code areas. An assembler / compiler will not
move these as long as the ORG statements do not change.

Hope someone finds it thought provoking.. Thanks for the opportunity and the
list, Steve and People!

Any feedback, public ridicule, etc is welcome ;-)

----- Original Message -----
From: steve ravet <sravet at arm.com>
To: <gmecm at diy-efi.org>
Sent: Wednesday, October 18, 2000 2:55 PM
Subject: new paper


> Dave Zug wrote some notes about modifying the code in a 727 to switch
> between 2 spark tables at startup.  At key on, the TPS setting is
> checked.  If you've got the pedal pushed it uses the new spark table,
> otherwise it uses the factory table.
>
> This technique can be used for anti theft (use a zero injector constant
> instead of the factory constant) or other things.  Look at the main
> gmecm page (www.diy-efi.org/gmecm), click papers, then "second spark
> table"
>
> thanks Dave,
> --steve
>
> --
> Steve Ravet
> steve.ravet at arm.com
> ARM,Inc.
> www.arm.com
> --------------------------------------------------------------------------
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