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Mathieu Maret 2017-01-28 23:44:16 +01:00
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Readme.md
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@ -1,22 +1,25 @@
== Instruction ==
# Instruction
Build with
nasm -f bin mbr.asm -o mbr
`nasm -f bin mbr.asm -o mbr`
Run with
qemu-system-x86_64 -boot a -fda mbr
`qemu-system-x86_64 -boot a -fda mbr`
Debug with
qemu-system-x86_64 -boot a -fda mbr -s -S
gdb
`qemu-system-x86_64 -boot a -fda mbr -s -S`
then
`gdb`
```
target remote localhost:1234
layout asm
b *0x7c00
c
```
== ASM reg ==
# ASM reg
=== In 16 bits ===
## In 16 bits
There is 4 main 16bits reg: AX, BX, CX, DX.
You can access the 8 MSB from AX with AH and the 8 LSB with AL.( BH,BL, CH, CL)
@ -26,32 +29,33 @@ SP is stack pointer, BP is base pointer
AX(AH, AL), BX(BH, BL), CX(CH, CL), DX(DH, DL), SI, DI, SP, BP
=== In 32bits ===
## In 32bits
Main register are "Extended" to 32bits but 16bits of 8bits direct access is not possible anymore.
EAX, EBX, ECX, EDX, ESI, EDI, ESP, EBP
=== In 64bits ===
## In 64bits
Prefixed by R
RAX, RBX, RCX, RDX, RSI, RDI, RSP, RBP
== Bios Memory ==
0x0 - 0x03FF ;IVT
0x400 - 0x4FF ;BIOS Data
0x500 - 0x7BFF ;Unused
0x7C00 - 0x7D77 ;Bootloader
0x7E00 - 0x9FFFF ;Unused
0xA0000 - 0xBFFFF ;Video memory
0xB0000 - 0xB7777 ;Video memory monochrome
0xB8000 - 0xBFFFF ;Video memory color
0xC0000 - 0xC7FFF ;BIOS ROM
0x80000 - 0xEFFFF ;BIOS shadow memory
0xF0000 - 0xFFFFF ;BIOS System
# Bios Memory
Address range | Description
----------------------- | -----------------------
0x0 - 0x03FF |IVT
0x400 - 0x4FF |BIOS Data
0x500 - 0x7BFF |Unused
0x7C00 - 0x7D77 |Bootloader
0x7E00 - 0x9FFFF |Unused
0xA0000 - 0xBFFFF |Video memory
0xB0000 - 0xB7777 |Video memory monochrome
0xB8000 - 0xBFFFF |Video memory color
0xC0000 - 0xC7FFF |BIOS ROM
0x80000 - 0xEFFFF |BIOS shadow memory
0xF0000 - 0xFFFFF |BIOS System
== Interrupt Vector Table ==
# Interrupt Vector Table
INT_NUM | Short Description PM
----------- | ----------------------
0x00 | Division by zero
@ -74,8 +78,8 @@ INT_NUM | Short Description PM
0x11 | Alignment Check
0x12 | Machine Check
0x13 | SIMD Floating-Point Exception
0x14 | Virtualization Exception
0x14 | Virtualisation Exception
0x15 | Control Protection Exception
== BIOS IRQ ==
# BIOS IRQ
https://en.wikipedia.org/wiki/BIOS_interrupt_call