ARM9 Unknown registers:
| Address:Width | Access | Purpose |
| 0x04000060:16 | 4fff | Unknown |
| 0x04000064:16 | 1f1f | Unknown |
| 0x04000066:16 | R/W | Unknown* |
| 0x040000E0:16 | ffff | Unknown |
| 0x040000E2:16 | ffff | Unknown |
| 0x040000E4:16 | ffff | Unknown |
| 0x040000E6:16 | ffff | Unknown |
| 0x040000E8:16 | ffff | Unknown |
| 0x040000EA:16 | ffff | Unknown |
| 0x040000EC:16 | ffff | Unknown |
| 0x040000EE:16 | ffff | Unknown |
| 0x04000182:16 | 8505 | Unknown |
| 0x04000320:16 | read-only | Reads 3f |
| 0x04000602:16 | c600 | Reads 3f |
* neat (stabilizes at 6f3f, b12 is w or ignored, but b15 isstart/enable/something, and stays set for ~1 frame before going low)
Metroid hits:
0x04000358:32
330
350
360
4D0
35C
600
ARM7 Unknown registers:
| Address:Width | Access | Purpose |
| 0x04000140:16 | 00c0 | Unknown |
| 0x04000158:16 | 0030 | Unknown |
| 0x04000184:16 | 8505 | Unknown, clears to 0101 |
Code to test later (written away from passthrough):