The PC's Physical Address Space
+------------------+ <- 0xFFFFFFFF (4GB)
| 32-bit |
| memory mapped |
| devices |
| |
//////////
//////////
| |
| Unused |
| |
+------------------+ <- depends on amount of RAM
| |
| |
| Extended Memory |
| |
| |
+------------------+ <- 0x00100000 (1MB)
| BIOS ROM |
+------------------+ <- 0x000F0000 (960KB)
| 16-bit devices, |
| expansion ROMs |
+------------------+ <- 0x000C0000 (768KB)
| VGA Display |
+------------------+ <- 0x000A0000 (640KB)
| |
| Low Memory |
| |
+------------------+ <- 0x00000000
BootStrap
1. BOIS: execute 1st instruction at f000:fff0, this address means it is executed directly in the ROM device, in witch BIOS stores.
2. Boot Loader: execute 1st instruction at 0000:7c00, this address means it is executed in memory RAM.
3. Kernel