Shutdown the computer using assembly

Question

How can I shutdown the computer using only assembly code?

Answer 1

Converting @larz answer above to nasm assembly is done as follows:

Prerequisites: Bochs, Nasm

This example was run on debian wheezy with standard packages.

Code (filename: shutdown.asm):

    org 0x7c00
    jmp main

Shutdown:
    mov ax, 0x1000
    mov ax, ss
    mov sp, 0xf000
    mov ax, 0x5307
    mov bx, 0x0001
    mov cx, 0x0003
    int 0x15

WaitForEnter:
    mov ah, 0
    int 0x16
    cmp al, 0x0D
    jne WaitForEnter
    ret

main:   
    call WaitForEnter
    call Shutdown

times 510-($-$$) db 0
dw 0xaa55

Nasm compliation:

nasm -f bin -o boot_sect.img shutdown.asm

Bochs configuration file (filename: .bochsrc) in the same directory as code (shutdown.asm)

display_library: sdl
floppya: 1_44=boot_sect.img, status=inserted
boot: a

*Note I am using the sdl library for bochs which is a seperate package from bochs itself

Running bochs (from the same directory as before):

bochs

Hit enter to shutdown

*Note I am not sure that all the lines between the Shutdown label and WaitForEnter label are neccessary