NSF Driver: FDS read-write register padding

[Gumball2415]

when using FDS in some NSF player implementations, the memory region in $8000-DFFF becomes read-writeable due to the FDS RAM adapter. this means that any chips that has their audio registers in this region will inevitably overwrite any data/code that happens to be there.

to avoid overwriting any data/code, we can add padding around these addresses as a workaround:

• VRC6
  • $9000-$9003
  • $A000-$A002
  • $B000-$B002
• VRC7
  • $9010
  • $9030
• Sunsoft 5B
  • $C000 (no mirrored address should be used)
  • $E000 (no mirrored address should be used)