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GAB
firelight.flagboy edited this page Aug 3, 2021
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The Gameboy use a 16-bit address bus, so the gameboy is limited to address in the range 0-0xffff (or 0-65535) that 64KiB of mapped data
The Adress bus is mapped like the following:
| Type | Lower Bound | Upper Bound | Description |
|---|---|---|---|
| ROM | 0x0000 |
0x7FFF |
ROM data area (readonly) |
| Video RAM | 0x8000 |
0x9FFF |
|
| External RAM | 0xA000 |
0xBFFF |
Optional RAM provided by the Cartridge |
| RAM | 0xC000 |
0xDFFF |
Internal RAM provided by the Gameboy |
| ERAM | 0xE000 |
0xFDFF |
Echo RAM, mirror of [0xC000-0xDDFF]
|
| OAM RAM | 0xFE00 |
0xFE9F |
Sprite Attribute Table |
0xFEA0 |
0xFEFF |
Not Usable | |
| I/O | 0xFF00 |
0xFF7F |
I/O register |
| HRAM | 0xFF80 |
0xFFFE |
High RAM (mean faster acess for GB) |
| IE | 0xFFFF |
0xFFFF |
Interrupt Enable Register |
Boot ROM or BIOS is code that is runned by the Gameboy before the ROM.
The BIOS is first map to 0x0000-0x00ff.
After success this area is taken over by the ROM of the cartridge.