Mo Assembly

[Dave Z]

I had posted this before.. but it seems appropriate to do it again 
here. I made a clever little patch to a car I used to have that 
allowed 2 (and later, more) different performance setups to reside on 
one single chip (no need to change them out for the good gas)

WARNING/DISCLAIMER: this info is intended for benchtop 
or offroad use by hobbiests and the like.  there.

You need enough spare space on your chip to hold the tables / vars 
you want to change, so if you have, say, an 89 camaro.. you'll have 
to do a bit of physical work to get ready first.. cause the chip is 
packed.

What I did, without posting code, was to simply insert a JSR just 
after the checksun routine, by replacing the code that followed with 
a JSR to a free location up high on the map. (dont forget to make the 
first instruction in the new area the instruction(s) whose space you 
used to insert the JSR) 

Within the new subroutine, compare the TPS position with a 50% 
value, and set a bit based on the results. ie full throttle at key-on 
time = "hi perf mode" bit set.  You need a spare RAM location to do 
this, or a spare BIT within a ram byte location.

RTS back, and let the normal stuff execute.. up until the SP(Program 
execution) hits, oh say, the main spark table. Insert another JSR to the free 
area again, and check the status of the "hi-perf" bit. If set, set 
the LDX that normally points to the start position of the table to 
another table that you have copied to the free area and modified for 
higher performance or even "valet" performance.. a cruel joke on the 
wife "this car's faster than this.. lemme drive!"  

last, RTS back and skip over the normal LDX for that table if you 
left that code there. allow the rest to execute.

If you spent ALOT of time, you could have several levels of 
perfomance on a single chip with no thumbwheel, but I like that idea 
as a more practical solution.. this "perf-bit" thing is an exercise 
in ASM mods and puts you above the "table hunters" some refer to. 
>From an 'X' table hunter, I say well you gotta start somewhere! so 
phooey on you ;-) (the smiley means its a light hearted comment.. no 
flaming please)

Sorry for the BW. My contribution for the month.


have fun.
Dave Z - 87 GN 12.74 @ 105 w/1.84 60'
               13.02 @ 103 on 94 octane
       - 89 IROC 5.7 Now Supercharged!
       - 89 Turbocharged GP 13.9 (retired)