CPU memory map: Difference between revisions
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Hamtaro126 (talk | contribs) (Major revision to include better mapping, and more!) |
(Don't give the idea that the vectors are some separate area of memory, just data at the end of cart space) |
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{| | {| class="tabular" | ||
! Addr || Size || Device | ! Addr || Size || Device | ||
|- | |- | ||
| Line 12: | Line 12: | ||
| $2000 || $0008 || [[PPU_registers|NES PPU]] registers | | $2000 || $0008 || [[PPU_registers|NES PPU]] registers | ||
|- | |- | ||
| $2008 || $1FF8 | | | $2008 || $1FF8 || Mirrors of $2000 every 8 bytes | ||
|- | |- | ||
| $4000 || $0018 || [[APU|NES APU]] and [[2A03|I/O registers]] | | $4000 || $0018 || [[APU|NES APU]] and [[2A03|I/O registers]] | ||
|- | |- | ||
| $4018 || $ | | $4018 || $BFE8 || Cartridge Space: PRG-ROM, PRG-RAM, and [[MMC|Mapper Registers]] (See Note) | ||
|} | |} | ||
Note: Most Common Boards address ROM and Save/Work RAM in this format, Especially in Common INES mappers: | Note: Most Common Boards address ROM and Save/Work RAM in this format, Especially in Common INES mappers: | ||
$6000-$7FFF = Battery Backed Save or Work RAM | *$6000-$7FFF = Battery Backed Save or Work RAM | ||
*$8000-$FFF9 = Usual ROM, commonly with Mapper Registers (see MMC1 and UxROM for example) | |||
$8000-$FFF9 = Usual ROM, commonly with Mapper Registers (see MMC1 and UxROM for example) | |||
The CPU expects three addresses called "vectors" in fixed places at the end of the cartridge space, like so: | |||
$FFFC-$FFFD = Reset vector | *$FFFA-$FFFB = NMI vector | ||
*$FFFC-$FFFD = Reset vector | |||
*$FFFE-$FFFF = IRQ/BRK vector | |||
$ | Any mapper that switches $E000-$FFF9 will switch $FFFA-$FFFF along with it. | ||
If a mapper doesn't fix $C000-$FFFF to the last bank or use some sort of reset detection, the vectors need to be stored in all banks. | |||
Revision as of 22:15, 20 July 2012
| Addr | Size | Device |
|---|---|---|
| $0000 | $0800 | 2KB internal RAM |
| $0800 | $0800 | Mirrors of $0000-$07FF |
| $1000 | $0800 | |
| $1800 | $0800 | |
| $2000 | $0008 | NES PPU registers |
| $2008 | $1FF8 | Mirrors of $2000 every 8 bytes |
| $4000 | $0018 | NES APU and I/O registers |
| $4018 | $BFE8 | Cartridge Space: PRG-ROM, PRG-RAM, and Mapper Registers (See Note) |
Note: Most Common Boards address ROM and Save/Work RAM in this format, Especially in Common INES mappers:
- $6000-$7FFF = Battery Backed Save or Work RAM
- $8000-$FFF9 = Usual ROM, commonly with Mapper Registers (see MMC1 and UxROM for example)
The CPU expects three addresses called "vectors" in fixed places at the end of the cartridge space, like so:
- $FFFA-$FFFB = NMI vector
- $FFFC-$FFFD = Reset vector
- $FFFE-$FFFF = IRQ/BRK vector
Any mapper that switches $E000-$FFF9 will switch $FFFA-$FFFF along with it. If a mapper doesn't fix $C000-$FFFF to the last bank or use some sort of reset detection, the vectors need to be stored in all banks.
