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SNES Memory Mapping
+=-=-=-=-=-=-=-=-=-=-=+
| SNES Memory Mapping |
| By: ]SiMKiN[ |
| v1.0 |
+=-=-=-=-=-=-=-=-=-=-=+
• LoROM: Mode 20
• HiROM: Mode 21
• 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.
+=========+=============+====================================+=========+
| Bank | Offset | Definition | Shadow |
+=========+=============+====================================+=========+
| $00-$2f | $0000-$1fff | LowRAM, each bank is shadowed | $00-$3f |
| | | From bank $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, 21 - ROM) | ------- |
+---------+-------------+------------------------------------+---------+
| $30-$3f | $0000-$1fff | LowRAM, each bank is shadowed | $00-$3f |
| | | From bank $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 20, 21 - ROM) | ------- |
+---------+-------------+------------------------------------+---------+
| $40-$6f | $0000-$7fff | (Mode 21 - ROM) | ------- |
| | $8000-$ffff | (Mode 20, 21 - ROM) | ------- |
+---------+-------------+------------------------------------+---------+
| $70-$77 | $0000-$ffff | (Mode 20, 21 - SRAM) 256KBytes | ------- |
+---------+-------------+------------------------------------+---------+
| $78-$7d | $0000-$ffff | Never Used | ------- |
+---------+-------------+------------------------------------+---------+
| $7e | $0000-$1fff | LowRAM | $00-$3f |
| | | Shadowed to banks $00-$3f | ------- |
| | $2000-$7fff | HighRAM | ------- |
| | $8000-$ffff | Expanded Ram | ------- |
+---------+-------------+------------------------------------+---------+
| $7f | $0000-$ffff | More Expanded RAM | ------- |
+---------+-------------+------------------------------------+---------+
| $80-$ef | $0000-$ffff | Mirror of $00-$6f | $00-$6f |
+---------+-------------+------------------------------------+---------+
| $f0-$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: Y0SHi, zsKnight, MrGrim, and MintaBoo_)o.
