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- +=-=-=-=-=-=-=-=-=-=-=+
- | SNES Memory Mapping |
- | By: ]SiMKiN[ |
- | v2.0 |
- +=-=-=-=-=-=-=-=-=-=-=+
- • FastROM's can execute at 3.58Mhz
- • SlowROM's can only execute 2.68Mhz
- • The SNES lets you access ROM through bank $00 onwards and bank
- $80 onwards such that locations $00:8000 and $80:8000 are congruent,
- (they access the same locations.)
- • When accessing bank $00 onwards the 65816 runs at 2.68Mhz. However,
- when accessing bank $80 onwards the 65816 can run at 2.68Mhz or
- 3.58Mhz depending on how you set bit 0 of $420D.
- • This Document Contains Information Regarding ROM's upto 32mbit.
- If you have any information regarding ROM's above 32mbit please send
- E-Mail to 'simkin@innocent.com'
- +======================================================================+
- | Mode 20: LoROM Memory Model (32k Banks) |
- | --------------------------------------- |
- | • $80-$ef : $8000-$ffff |
- | Mirrored to $00-6f |
- | • $f0-$ff : $8000-$ffff |
- +=========+=============+====================================+=========+
- | Bank | Offset | Definition | Shadow |
- +=========+=============+====================================+=========+
- | $00-$2f | $0000-$1fff | LowRAM, shadowed from $7e | $7e |
- | | $2000-$2fff | PPU1, APU | $00-$3f |
- | | $3000-$3fff | SFX, DSP, etc. | $00-$3f |
- | | $4000-$41ff | Controller | $00-$3f |
- | | $4200-$5fff | PPU2, DMA, etc. | $00-$3f |
- | | $6000-$7fff | RESERVED | $00-$3f |
- | | $8000-$ffff | (Mode 20 ROM) | ------- |
- +---------+-------------+------------------------------------+---------+
- | $30-$3f | $0000-$1fff | LowRAM, shadowed from $7e | $7e |
- | | $2000-$2fff | PPU1, APU | $00-$3f |
- | | $3000-$3fff | SFX, DSP, etc. | $00-$3f |
- | | $4000-$41ff | Controller | $00-$3f |
- | | $4200-$5fff | PPU2, DMA, etc. | $00-$3f |
- | | $6000-$7fff | RESERVED | ------- |
- | | $8000-$ffff | (Mode 20 ROM) | $80-$bf |
- +---------+-------------+------------------------------------+---------+
- | $40-$6f | $0000-$7fff | RESERVED | ------- |
- | | $8000-$ffff | (Mode 20 ROM) | $C0-$EF |
- +---------+-------------+------------------------------------+---------+
- | $70-$77 | $0000-$ffff | (Mode 20 SRAM) 256KBytes | ------- |
- +---------+-------------+------------------------------------+---------+
- | $78-$7d | $0000-$ffff | RESERVED | ------- |
- +---------+-------------+------------------------------------+---------+
- | $7e | $0000-$1fff | LowRAM | $00-$3f |
- | | $2000-$7fff | HighRAM | ------- |
- | | $8000-$ffff | Expanded RAM | ------- |
- +---------+-------------+------------------------------------+---------+
- | $7f | $0000-$ffff | Expanded RAM | ------- |
- +---------+-------------+------------------------------------+---------+
- | $80-$ef | $0000-$ffff | Mirror of $00-$6f | $00-$6f |
- +---------+-------------+------------------------------------+---------+
- | $f0-$ff | $0000-$7fff | RESERVED | ------- |
- | | $8000-$ffff | (Mode 20 ROM) | ------- |
- +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+
- +======================================================================+
- | Mode 21: HiROM Memory Model (64k Banks) |
- | --------------------------------------- |
- | • $C0-$ff : $0000-$ffff |
- | High Parts ONLY '($8000-$ffff)' are Shadowed to $00-3f |
- +=========+=============+====================================+=========+
- | Bank | Offset | Definition | Shadow |
- +=========+=============+====================================+=========+
- | $00-$2f | $0000-$1fff | LowRAM, shadowed from $7e | $7e |
- | | $2000-$2fff | PPU1, APU | $00-$3f |
- | | $3000-$3fff | SFX, DSP, etc. | $00-$3f |
- | | $4000-$41ff | Controller | $00-$3f |
- | | $4200-$5fff | PPU2, DMA, etc. | $00-$3f |
- | | $6000-$7fff | RESERVED | $00-$3f |
- | | $8000-$ffff | (Mode 21 ROM) from $C0-$EF | $C0-$EF |
- +---------+-------------+------------------------------------+---------+
- | $30-$3f | $0000-$1fff | LowRAM, shadowed from $7e | $7e |
- | | $2000-$2fff | PPU1, APU | $00-$3f |
- | | $3000-$3fff | SFX, DSP, etc. | $00-$3f |
- | | $4000-$41ff | Controller | $00-$3f |
- | | $4200-$5fff | PPU2, DMA, etc. | $00-$3f |
- | | $6000-$7fff | (Mode 21 SRAM) 256KBytes | ------- |
- | | $8000-$ffff | (Mode 21 ROM) from $C0-$EF | $C0-$EF |
- +---------+-------------+------------------------------------+---------+
- | $40-$6f | $0000-$7fff | (Mode 21 ROM) from $C0-$EF | $C0-$EF |
- +---------+-------------+------------------------------------+---------+
- | $70-$77 | $0000-$ffff | (Mode 20 SRAM) 256KBytes | ------- |
- +---------+-------------+------------------------------------+---------+
- | $78-$7d | $0000-$ffff | RESERVED | ------- |
- +---------+-------------+------------------------------------+---------+
- | $7e | $0000-$1fff | LowRAM | $00-$3f |
- | | $2000-$7fff | HighRAM | ------- |
- | | $8000-$ffff | Expanded RAM | ------- |
- +---------+-------------+------------------------------------+---------+
- | $7f | $0000-$ffff | Expanded RAM | ------- |
- +---------+-------------+------------------------------------+---------+
- | $80-$bf | $0000-$ffff | Mirror of $00-$3f | $00-$3f |
- +---------+-------------+------------------------------------+---------+
- | $c0-$ff | $0000-$ffff | (Mode 21 ROM) | ------- |
- +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+
- • ROM: The SNES ROM Image
- • RAM: The SNES Work Memory (WRAM)
- LowRAM, HighRAM, & Expanded RAM
- All together = 128 Kilo-Bytes
- • SRAM: Save RAM (Extra RAM added by Cart)
- The SNES only utilizes 256 Kilo-bits
- However 256 Kilo-Bytes are provided.
- • APU: Audio Processing Unit
- SPC700, Inside which has a DSP
- • PPU: Picture Processing Unit
- PPU1: 5c77-01
- PPU2: 5c78-03
- • SFX: Super FX Cart Chip, by Nintendo
- • DSP: Digital Signal Processing Cart Chip
- a.k.a. 'NEC mUPD77C25'
- • Shadow: "Congruent Bank". Same meaning as Mirror.
- _____________________________________________________
- .o(_Thanx to: zsKnight, Lord Esnes, Y0SHi, and MintaBoo_)o.
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