I wrote a small bootloader that i write in a Diskette, the bootloader is working fine, i write a function to reboot the PC, but i can't shutdown the PC, i try a lot but i've just got an infinite beep song from the speaker. I'm in boot mode, so windows interruptions doesn't work. How can i do it? I'm compiling with NASM and write in diskette with Rawriter.
I had tried a code that i see here in Stackoverflow, but it doesn't works.
MOV AX,5307
MOV BX,0001
MOV CX,0003
INT 15
And i tried that another too
mov ax, 0x1000
mov ax, ss
mov sp, 0xf000
mov ax, 0x5307
mov bx, 0x0001
mov cx, 0x0003
int 0x15
How far you do want to go with this?
Because shutting down a computer is chipset specific, the hardware programming interface has never been standardized.
However a software interface has been standardized, actually two have been: Advanced Power Management (APM) and Advanced Configuration And Power Interface (ACPI).
While the first is really easy and it is the one you are using, it is very very old (in computer industry years). I have made a simple boot program that use APM to shutdown the computer. It does all the things pedantically in the proper way.
With Bochs it works. On real hardware (tested on 3 laptops) it doesn't and prints the error code A which means No APM service found.
This seems to suggest that the APM interface is no longer supported, this didn't surprise me to be honest I was expecting it and the converse would have.
So you are left with the ACPI, now unless you are really familiar with it I simply suggest you to not dig into that (rather if your is a specific solution get your chipset datasheet) as it is quite elaborate, and has specific terminology and it handle the whole aspect of power management.
You would have to find and parse various tables, interpret AML code sequences, setup a proper environment, it will take a long long time.
The closest thing to a shutdown without APM or ACPI is the well known
cli
hlt
instruction pair.
If you are interested in the APM boot program to give it a try, here it is
BITS 16
jmp 07c0h:WORD __START__
__START__:
mov ax, cs
mov ss, ax
xor sp, sp
push cs
pop ds
push WORD 0b800h
pop es
mov ax, 03h
int 10h
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Check APM service is present
mov BYTE [error], 'A'
mov ax, 5300h
xor bx, bx
int 15h
jc .err
inc BYTE [error]
cmp bx, 504dh
jne .err
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Connect RM interface, compatibility mode APM 1.0
inc BYTE [error]
mov ax, 5301h
xor bx, bx
int 15h
jc .err
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Switch to APM 1.1+
inc BYTE [error]
mov ax, 530eh
xor bx, bx
mov cx, 0101h
int 15h
jc .err
inc BYTE [error]
cmp al, 01h
jb .err
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Enable APM
inc BYTE [error]
mov ax, 5308h
mov bx, 01h
mov cx, 01h
int 15h
jc .err
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Engage APM
inc BYTE [error]
mov ax, 530fh
mov bx, 01h
mov cx, 01h
int 15h
jc .err
;^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
; \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
; v v v v v v v v v v v v v v v v v
;Shutdown
inc BYTE [error]
mov ax, 5307h
mov bx, 01h
mov cx, 03h
int 15h
jc .err
jmp .end
.err:
xor di, di
mov ah, 09h
mov al, BYTE [error]
stosw
.end:
cli
hlt
error db 0
TIMES 505-($-__START__) db 0
dw 0aa55h