Hardware
- 0000-3FFF : Fixed ROM bank (8K)
- 4000-7FFF : Bank-switched ROM (8K)
- 8000-9FFF : VRAM (tiles, palettes, maps)
- A000-BFFF : Space for cartridge RAM, if any, which might be battery-backed
- C000-FEFF : Main RAM
- FF00-FFFF : I/O ports and high RAM
Bank Switchers
There were several on-cartridge chips to manage cartridge memory bank switching (RAM and ROM).
MB1: write anywhere from 2000-3FFF to select a ROM bank at 4000-7FFF. The value written is the bank number. Write anywhere from 4000-5FFF selects a RAM bank from A000-C000.
VRAM
TODO describe formats, windows, etc
- 8000-97FF : Character RAM
- 9800-9BFF : BG Map Data 1
- 9C00-9FFF : BG Map Data 2
- FE00-FE9F : Object Attribute Memory
I/O Ports and High RAM
FF80-FFFE is an area of RAM called High RAM -- HRAM.
| FF00 | JOYPAD | Joypad port |
| FF01 | SIODATA | Serial I/O Data |
| FF02 | SIOCNT | Serial I/O Control |
| FF04 | DIVIDER | Meaning unknown |
| FF05 | TIMECNT | Timer Counter |
| FF06 | TIMERMOD | Timer Modulo |
| FF07 | TIMERCONT | Timer Control |
| FF0F | IFLAGS | Interrupt Flags |
| FF10 | SNDREG10 | Sweep #1 |
| FF11 | SNDREG11 | Sound length/pattern duty #1 |
| FF12 | SNDREG12 | Control #1 |
| FF13 | SNDREG13 | Frequency low #1 |
| FF14 | SNDREG14 | Frequency high #1 |
| FF16 | SNDREG21 | Sound length/pattern duty #2 |
| FF17 | SNDREG22 | Control #2 |
| FF18 | SNDREG23 | Frequency low #2 |
| FF19 | SNDREG24 | Frequency high #2 |
| FF1A | SNDREG30 | Control #3 |
| FF1B | SNDREG31 | Sound length #3 |
| FF1C | SNDREG32 | Output level #3 |
| FF1D | SNDREG33 | Frequency low #3 |
| FF1E | SNDREG34 | Frequency high #3 |
| FF20 | SNDREG41 | Sound length/pattern duty #4 |
| FF21 | SNDREG42 | Control #4 |
| FF22 | SNDREG43 | Polynomial counter #4 |
| FF23 | SNDREG44 | Frequency high #4 |
| FF24 | SNDREG50 | Channel and volume control |
| FF25 | SNDREG51 | Sound output terminal selector |
| FF26 | SNDREG52 | Sound on/off |
| FF40 | LCDCONT | LCD control |
| FF41 | LCDSTAT | LCD status |
| FF42 | SCROLLY | Background vertical scrolling |
| FF43 | SCROLLX | Background horizontal scrolling |
| FF44 | CURLINE | Current scanline |
| FF45 | CMPLINE | Scanline comparison |
| FF47 | BRGDPAL | Background palette |
| FF48 | OBJ0PAL | Sprite palette #0 |
| FF49 | OBJ1PAL | Sprite palette #1 |
| FF4A | WNDPOSY | Window Y position |
| FF4B | WNDPOSX | Window X position |
| FFFF | ISWITCH | Interrupt Enable/Disable |