Just for kicks, I bet we could take this a step further and make the MOD3TEST a bit conditional based on the presence of PGC. So something like this:
1) At start of MOD3TEST, instead jump to some free area in the ROM and probe for PGC.
2) If PGC exists, start MOD3TEST (basically what was overwritten), then patch back into MOD3TEST and have MOD3TEST exit after first write.
3) Else (if PGC does not exist), 4ED6.
4) Always 4ED6 out of REVMOD3TEST.
1) At start of MOD3TEST, instead jump to some free area in the ROM and probe for PGC.
2) If PGC exists, start MOD3TEST (basically what was overwritten), then patch back into MOD3TEST and have MOD3TEST exit after first write.
3) Else (if PGC does not exist), 4ED6.
4) Always 4ED6 out of REVMOD3TEST.
