Hello, all. Looking for some guidance or help with respect to how I might find a certain RAM address in the Mega Drive / Genesis game, T2 – The Arcade Game. I’m specifically looking for the “health” counter for the van in the Freeway stage.
Here's what I've done so far:
1) Determined that in a previous stage (Trip to Skynet stage) the destruction of the automobile was determined in part by a counter adding up to a certain amount, so I made an assumption that to zero out a certain RAM address will also render the van in the Freeway stage indestructible. This is not a perfect assumption, but it led me to be able to render the automobile in that Trip to Skynet level virtually indestructible by NOP’ing a TST.B function.
2) Used a RAM search to determine and record what addresses went from 0 to 1 the moment the helicopter hits the van in the Freeway stage. For each address, created a PAR code to set the address to zero. Tested each PAR code on the Freeway level. Each time, the van was destroyed or some other operation was corrupted.
3) Used a trace log to identify commands where a RAM address was written to during the time before and after the van was impacted (could not precisely pinpoint the exact moment, however, so the log is several megabytes). Created PAR codes setting each address to zero and tested. Each time, the van was destroyed or some other operation was corrupted. Addresses tested: $78C2; $765E; $77F0; $13F7E; $086C; $FBC1E; $FC4FA; and $13CC8.
4) From the trace log, documented all instances of a TST.B function and NOP’d and tested each. Each time, the van was destroyed or some other operation was corrupted. (Note these TST.B functions were not the same opcodes as the one in the previous level), that one being a TST.B $00(A1,D0) command.
Any other ideas or approaches as to how I might find this value, assuming it exists in the manner I’m assuming?