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gba/book/src-bak/08-rom.md
Lokathor 09b4c8804c YABU: Yet Another Book Update
2018-12-29 20:18:09 -07:00

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Game Pak ROM / Flash ROM (ROM)

  • Address Span (Wait State 0): 0x800_0000 to 0x9FF_FFFF
  • Address Span (Wait State 1): 0xA00_0000 to 0xBFF_FFFF
  • Address Span (Wait State 2): 0xC00_0000 to 0xDFF_FFFF

The game's ROM data is a single set of data that's up to 32 megabytes in size. However, that data is mirrored to three different locations in the address space. Depending on which part of the address space you use, it can affect the memory timings involved.

TODO: describe WAITCNT here, we won't get a better chance at it.

TODO: discuss THUMB vs ARM code and why THUMB is so much faster (because ROM is a 16-bit bus)