The code is A082:DF
I'm disassembling the effects of the code:
On bank 0E:
There's a CALL instruction for address A0A1. The code instead changes it to address A0DF.
0E:A081:20 A1 A0 JSR $A0A1
Normally the code in that area looks like this:
0E:A0DD:8D FB 07 STA $07FB
0E:A0E0:CE FD 07 DEC $07FD
0E:A0E3:D0 51 BNE $A136
0E:A0E5:A4 73 LDY $0073
0E:A0E7:E6 73 INC $0073
0E:A0E9:B9 C5 A1 LDA $A1C5,Y @ $A1C5
0E:A0EC:F0 04 BEQ $A0F2
0E:A0EE:10 1F BPL $A10F
0E:A0F0:D0 10 BNE $A102
0E:A0F2:A9 08 LDA #$08
0E:A0F4:8D 15 40 STA $4015
But we jumped into the middle of an instruction, so instead the code looks like this:
SLO $CE*
SBC $D007,X
EOR ($A4),Y
RRA ($E6),Y*
RRA ($B9),Y*
CMP $A1
*Illegal instructions, SLO shifts memory left, RRA rotates memory right
So here, we lost some original game logic where it loads values from memory, increments some values, and peforms checks on those values, and instead we have crap executed.
Now, it has performed bit shifting/rotation on memory at $CE, ($E6 + Y), and ($B9 + Y). The indirect addresses happened to be in Zeropage at the time, so they weren't mapper writes, but it's still corrupting some other variable. And register A now contains something it's not supposed to contain at that point.
Then on bank 03:
Original code:
03:A082:C9 5B CMP #$5B
03:A084:D0 57 BNE $A0DD
03:A086:AC 0A 07 LDY $070A
03:A089:C0 04 CPY #$04
03:A08B:F0 0C BEQ $A099
03:A08D:C0 08 CPY #$08
03:A08F:F0 08 BEQ $A099
New code:
DCP $505B*
SRE $AC,X*
ASL A
SLO $C0*
DOP $F0*
TOP $08C0*
BEQ $A099 (aligned back to original code again)
*Illegal instructions. DOP and TOP do nothing, DCP decreases memory, SRE shifts memory right, SLO shifts memory left.
So this game genie code is a bunch of crap that just corrupts some memory every frame, and prevents original code from running. Nothing worth TASing.
