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Old 06-13-2024   #2
tpepmeie
 
Join Date: Aug 2005
Location: Fishers, IN
Posts: 812
Default Re: More BMCB BIN spelunking. A few unknown addresses with changes.

Remember, those raw addresses all start a 0x8000h.

Code:
86FB	86FB	KPTCOOL	PORT THROTTLE ENABLE MIN COOL TEMP
86FC	86FC	KPTHCOLD  PORT THROTTLE DISABLE MAX COOL TEMP
86FD	86FD	KPTHCOLR	  PORT THROTTLE RE-ENABLE COOL TEMP
86FE	86FE	KPTLOTE  PORT THROTTLE ENABLE MIN OIL TEMP
86FF	86FF	KPTHOTD  PORT THROTTLE DISABLE MAX OIL TEMP
8700	8700	KPTHOTR  PORT THROTTLE RE-ENABLE OIL TEMP
8701	8701	KPTVOLT  PORT THROTTLE ENABLE MIN VOLTAGE
8702	8702	KPTVOLTH  PORT THROTTLE VOLTAGE HYSTERESIS

B3BC: This is the byte change that causes the program to startup in full power mode

BEDC and BEDD: This is part of the EST (spark timing) minor loop. Changing 0x4E to 0x00 is totally odd. It's a BCLR command (the bit to clear is EST enable), in the event that the stall saver logic is active. I would not recommend that change. In effect, whoever made that change is keeping EST spark control active while the engine is in stall saver mode.


BEDE: Same routine as above. The 0x0F is an instruction to set a program interrupt, which is supposed to happen at that point. I would not make that change.

BEDF: the 0x45 is an instruction (JSR=Jump to Subroutine) which is supposed to happen next. That subroutine sends a command to another chipset on the board. WTH were they trying to accomplish by changing that to 0x00? Not a good idea, IMO.

I can only suspect they were changing these bytes to sort of leave a "marker" to identify their calibration somehow. Without understanding what was there.
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