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[TkTech]

This is just about the bare minimum for jumping to PMode. It doesn't set up A20, so your limited to 16MB, but its good if your trying to fit a program into a single sector.

[highlight=asm]
; I was bored, echo said to do something hardware related...

; Jump to PMODE
[BITS 16]
[ORG 0x7C00]

cli ; Disable interrupts; Cleanup registers
xor ax, ax ; zero AX
mov ds, ax ; DS is used by lgdt

lgdt [gdt_desc] ; Load the GDT
mov eax, cr0 ; Load the value of cr0 (control register) into eax (general purpose register)
or eax, 1 ; OR (|) the value of eax with 1
mov cr0, eax ; Load the value of eax into cr0
jmp 0x8:main ; Far jump (dirty value in cs)

[BITS 32]

main:
mov ax, 10h ; Store data segment (10h)
mov ds, ax ; Store valid segment in ds
mov ss, ax ; Store valid segment it ss
mov esp, 0x90000 ; Shove the stack at 0x90000

;; Make your program

jmp $
; GDT Must have 3 entries
;...Null...
gdt_null: dd 0
dd 0
;...Code segment...
gdt_code: dw 0x0FFFF ; limit low
dw 0 ; base low
db 0 ; base mid
db 10011010b ; access
db 11001111b ; granularity
db 0 ; base high
;...Data segment...
gdt_data: dw 0x0FFFF ; limit low
dw 0 ; base low
db 0 ; base mid
db 10010010b ; access
db 11001111b ; granularity
db 0 ; base high
gdt_end:

;...GDT Descripor
gdt_desc: dw gdt_end - gdt_null - 1; limit
dd gdt_null ; base

times 510-($-$$) db 0 ; Pad the file to 512 bytes
db 0x55 ; Boot signature
db 0xAA
[/highlight]

Grr, all the [ above should be [