diff options
| -rw-r--r-- | baremetal/boot.hex | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/baremetal/boot.hex b/baremetal/boot.hex index e025efb3..44c197b9 100644 --- a/baremetal/boot.hex +++ b/baremetal/boot.hex @@ -31,7 +31,23 @@ # - can't use any syscalls # - can't print text to video memory (past these boot sectors) # - must only print raw pixels (256 colors) to video memory (resolution 1024x768) -# - must store their entry-point at address 0x9000 +# - must start executing immediately after this file (see outline below) + +# Outline of this file with offsets and the addresses they map to at run-time: +# offset 0 (address 7c00): boot code, 16-bit mode +# 80 (address 7c80) global descriptor table +# a0 (address 7ca0) <== gdt_descriptor +# offset e0 (address 7ce0): boot code +# offset 100 (address 7d00): interrupt handler code +# 1c8 (address 7dc8) <== keyboard buffer +# 1f8 (address 7df8) <== idt_descriptor +# 1fe (address 7dfe) boot sector marker (2 bytes) +# offset 200 (address 7e00): interrupt descriptor table (256 bytes) +# offset 300 (address 7f00): video mode data (256 bytes) +# 328 (address 7f28) <== start of video RAM stored here +# offset 400 (address 8000): keyboard mappings (2KB) +# offset c00 (address 8800): bitmap font (2KB) +# offset 1400 (address 9000): entrypoint for applications (don't forget to adjust survey_baremetal if this changes) ## 16-bit entry point |