MMC9001

2048kb max total space for both PRG ROM and PRG RAM (RAM starts at the beginning and ROM is placed at the end), dual ported
256kb dual-ported generic VRAM for nametables and CHR
Can read back what you wrote to any register unless otherwise stated
ARM co-processor (at some high multiple of the NES's clock speed, around 16Mhz or 32Mhz) with 32MB max ROM and 32MB max RAM
Initializes self on reset, detected by 6502 reset vector getting read. Any register not stated initializes to zero.

cccccccc $4200 - CHR select $0000-$03ff (1kb) - initializes to bank 0
cccccccc $4201 - CHR select $0400-$07ff (1kb) - initializes to bank 1
cccccccc $4202 - CHR select $0800-$0bff (1kb) - initializes to bank 2
cccccccc $4203 - CHR select $0c00-$0fff (1kb) - initializes to bank 3
cccccccc $4204 - CHR select $1000-$13ff (1kb) - initializes to bank 4
cccccccc $4205 - CHR select $1400-$17ff (1kb) - initializes to bank 5
cccccccc $4206 - CHR select $1800-$1bff (1kb) - initializes to bank 6
cccccccc $4207 - CHR select $1c00-$1fff (1kb) - initializes to bank 7
cccccccc $4208 - Nametable select $2000
cccccccc $4209 - Nametable select $2400
cccccccc $420a - Nametable select $2800
cccccccc $420b - Nametable select $2c00
pppppppp $420c - PRG select $6000-$7fff (8kb) - initializes to bank -5
pppppppp $420d - PRG select $8000-$9fff (8kb) - initializes to bank -4
pppppppp $420e - PRG select $a000-$bfff (8kb) - initializes to bank -3
pppppppp $420f - PRG select $c000-$dfff (8kb) - initializes to bank -2
pppppppp $4210 - PRG select $e000-$ffff (8kb) - initializes to bank -1

isbb.am $4211 - misc config stuff #1
|||||||+-- if 1, banks 0 and 1 refer to the NES's built-in nametable RAM instead of the CHR RAM, but only for nametables
||||||+--- if 1, enable ARM (setting to 1 after previously being 0 resets it)
|||||+---- if 1, alternate attributes between palette 0 and 1 every scanline
||||+----- if 1, bitmap mode is stored with each two bits being a color, instead of planar
||++------ if 1, enable bitmap mode ($421e used as a base for the whole screen)
||         if 2, bitmap mode, but second port of dual-ported VRAM is also used for rendering
||               and the bitmap's pixels take priority over the regular tiles creating an overlay
||         if 3, same, but regular tiles take priority over bitmap
|+-------- if 1, enable Namco 163 expansion sound
+--------- if 1, enable scanline counter IRQ

mmrfssss $4212 - MMC5 RAM nametable expansion config
||||++++-- if 1, pptttttt, P is palette and T is 4kb CHR bank
||||       if 2, ppxytttt, P is palette and T is 4kb CHR bank, X and Y flip a tile horizontally or vertically
||||       if 3, MMC5 RAM used to scroll each tile a given amount horizontally and vertically:
||||           xxxxyyyy, where Y is vertical, X is horizontal (signed); moves in color 0 from side if not moving in pixels
||||       if 4, similar to 3, but format is ppffxxxx, where P is palette, F is color to move in from the side if not tile pixels
||||       if 5, similar to 3, but format is ppffyyyy, where P is palette, F is color to move in from the side if not tile pixels
||||       if 6, similar to 3, but format is ff0dxxxx, where F is color to move in from the side if not tile pixels
||||             if D is 1, Y is used instead of X
||||             alternate format pp1xyttt, where P is palette, X and Y flip and TTT extend tiles
||||       if 7,
|||+-----  if 1, palette bits are replaced by XY, where X flips horizontally and Y flips vertically
||+------  if 1, double-render sprites as background too for infinite sprites per row
||               (watch for $02xx writes to detect sprites)
++-------  MMC1 mirroring select, but applying to what kilobyte affects what nametables

........ $4213 - Unused but reserved for config
........ $4214 - Unused but reserved for config
........ $4215 - Unused but reserved for config

nnnnnnnn $4216 - Scanline to generate IRQ at; read or write to acknowledge IRQs
xxxxxxxx $4217 - Multiplier Param A (write) / Low bits of product (read)
xxxxxxxx $4218 - Multiplier Param B (write) / High bits of product (read)
xxxxxxxx $4219 - Random number generator (read) / Max value for random number generator (write)
xxxxxxxx $421a - Write protect flags for the first eight banks of PRG RAM, from least significant to most significant bit
xxxxxxxx $421b - last value written to PPUCTRL ($2000)
xxxxxxxx $421c - last value written to PPUMASK ($2001)
xxxxxxxx $421d - bank to use as a base for the bitmap mode if enabled
xxxxxxxx $421e - bitmap mode scroll X
xxxxxxxx $421f - bitmap mode scroll Y
xxxxxxxx $4220 - Namco 163 expansion sound address
xxxxxxxx $4221 - Namco 163 expansion sound data
xxxxxxxx $4222 - 10000s digit of BCD number (read), low byte of number to convert (write)
xxxxxxxx $4223 - 1000s digit of BCD number (read), high byte of number to convert (write)
xxxxxxxx $4224 - 100s digit of BCD number (read)
xxxxxxxx $4225 - 10s digit of BCD number (read)
xxxxxxxx $4226 - 1s digit of BCD number (read)
xxxxxxxx $4227 - Division Param A (write, low), a / b (read, low)
xxxxxxxx $4228 - Division Param A (write, high), a / b (read, high)
xxxxxxxx $4229 - Division Param B (write), a % b (read)
es.wwwww $422a - MMC5 Vertical Split Mode
|| +++++- Specify vertical split start/stop tile
|+------- Specify vertical split screen side (0:left; 1:right)
+-------- Enable vertical split mode
xxxxxxxx $422b - MMC5 Vertical Split Scroll
xxxxxxxx $422c - MMC5 Vertical Split Bank
xxxxxxxx $422d - Force an interrupt on ARM (write), use shared NES/ARM memory to send parameters and get results back

bb.aaaaa $422e - DMA source bank
++------ if B = 0, PRG RAM/ROM
         if B = 1, CHR RAM; top 3 address bits not used for address
         if B = 2, on-board RAM that starts at $4400
         if B = 3, fill mode, use low 8 bits of address as value
aaaaaaaa $422f - DMA source high
aaaaaaaa $4230 - DMA source low
bbbaaaaa $4231 - DMA destination bank
aaaaaaaa $4232 - DMA destination high
aaaaaaaa $4233 - DMA destination low
xxxxxxxx $4234 - DMA length high
xxxxxxxx $4235 - DMA length low
xxxxxxxx $4236 - DMA offset per write high
xxxxxxxx $4237 - DMA offset per write low
ixxxxxxx $4238 - DMA action: (writing starts DMA)
|   ++++- if 0, copy
|         if 1, swap
|         if 2, add
|         if 3, subtract
|         if 4, or
|         if 5, an
|         if 6, xor
|         if 7,
+------- generate IRQ once DMA is completed

xxxxxxxx $4239 - IRQ reason (reading acknowledges)
          if 0: IRQ by non-mapper means
          if 1: IRQ by scanline counter
          if 2: IRQ by DMA completion
          if 3:

$4400 - $47ff  - shared 6502/ARM memory
$4800 - $4bff  - kilobyte for MMC5 stuff (nametable 1)
$4c00 - $4fff  - kilobyte for MMC5 stuff (nametable 2)

-----ARM's side-----
$00000000 - $01ffffff: ARM ROM (32MB)
$02000000 - $03ffffff: ARM RAM (32MB)
$04000000 - $04040000: CHR RAM (dual-ported so it can access even while NES renders)
$04100000 - $042fffff: PRG ROM/RAM (same banks as 6502 accesses)
$04300000 - 1kb of shared NES/ARM memory, then GameBoy Advance's sound registers, then DMA registers, then timer registers