assembly: indlæs sektor og eksekver

Jeg har en bootloader (xboot.asm) som skal boote min kerne (xkernel.asm).
Først laver jeg et reset på floppy, læser 2. sektor på floppy (sektoren umiddelbart efter bootsektoren), placer den i hukommelsen, og til sidst eksekvere det indlæste (køre kernen).
Min kode virker ikke efter hensigten - er der nogen der kan fortælle mig hvorfor?

(4 filer: xboot.asm, disk.inc, common.inc, xkernel.asm)

----xboot.asm----
[BITS 16]                    ; not protected mode yet
[ORG 0h]                    ; the offset (the boot sector is loaded into memory at 7C00h:0000h - (segment:offset))

    jmp    start                ; jumps to label "start"
    nop                    ; nop (no operation)

; include will insert the code in disk.inc and common.inc here
%include "disk.inc"
%include "common.inc"

    boot loader_info            db "XBoot, ver 0.06, by XexxeX @ 12/05-2005",13,10,"Created for the XOS",13,10,0
    pressanykey                db "Press any key to boot XOS",13,10,0
    kernel_read                db "Reading kernel ...",13,10,0
    boot_msg                db "Booting kernel ...",13,10,0

; code

start:                    ; the actual bootstrap begins here

    cli                    ; disable interrupts

    mov    ax, 0x07C0            ; point to where the boot sector starts
    mov    ds, ax            ; setup ds register
    mov    ax, 0x9000            ; DUNNO???
    mov    es, ax            ; setup a stack
    mov    sp, 0x1FFF            ; DUNNO???

    ; insert protected mode here!

    sti                    ; enable interrupts

    call    set_video_mode        ; inits the videomode
    call    set_background_color    ; changes the background color

    mov    si,boot loader_info
    call    print_string
    mov    si,pressanykey
    call    print_string
    call read_char
    mov si,kernel_read
    call print_string

;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! hertil ser det fint nok ud når der bootes
; men jeg ved ikke om problemet er at sektoren ikke indlæses, eller om den bare ikke eksekveres
    call    reset_floppy        ; resets the floppy drive
    call    read_kernel            ; reads the next sector on the disk = the kernel

    mov    si,boot_msg
    call    print_string

    mov    ax, 0100h              ; cant load directly into segments - so a temp register is used (ax)
    mov    ds, ax              ; Set the data segment register (ds) to point to the kernel location in memory
    jmp    0100h:0000h            ; goto what was just read into memory (the kernel)

; functions

set_video_mode:
    mov al,03h                ; select video mode 3 - color text
    mov ah,00h                ; set video mode function
    int 10h                ; call bios video services
    ret

set_background_color:
    mov ah,0Bh                ; sets up the register, so the pc will know that it should change the backgroundcolor
    mov bh,00h                ; -"-
    mov bl,01h                ; 00=black,01=blue,02=green (see "testscreencolor.asm" for more colors)
    int 10h
    ret

; signature

    times    510-($-$$) db 0        ; padding
    dw    0xAA55            ; boot signature

----common.inc----
print_string:                ; input : ds:si points to zero terminated string
    cld                    ; direction forward
    lodsb                    ; get next character
    cmp al,0h
    jz print_is_done            ; too bad there isn't an instruction called "call if not zero"
    call print_char
    jmp print_string
print_is_done:
    ret

print_char:
    mov ah,0Eh
;    mov cx,ABCDh            ; cx and bp may work if i make the bootstrap 32bits instead of 16bits
;    mov bp,ABCDh
                        ; al contains the char to write
    mov bh,00h                ; the "window" to write to (like multiple screens in linux)
    mov bl,07h                ; sets font color to grey
    int 10h
    ret

read_char:
    mov ah,00h                ; set ah up to read a keypress
    int 16h                ; wait for a key to be pressed
    ret

----disk.inc----
reset_floppy:
    mov    ah,00h                ; function to perform (reset drive)
    mov    dl,00h                ; drive (00h=a:)
    int    13h                    ; perform the action
    or    ah, ah                ; Check for error code
    jnz    reset_floppy            ; Try again if ah != 0
    ret

read_kernel:
; Code to load the second sector on the disk into memory location 0x0100:0x0000 (es:bx)

    mov    ax, 0100h                ; Segment location to read into (remember can't load direct to segment register)
    mov    es, ax                ; es = extended segment
    mov    bx, 0000h                ; Offset to read into
    mov    ah, 02h                ; BIOS read sector function
    mov    al, 01h                ; read one sector
    mov    ch, 00h                ; Track to read
    mov    cl, 02h                ; Sector to read
    mov    dh, 01h                ; Head to read
    mov    dl, 00h                ; Drive to read
    int    13h                    ; Make the BIOS call (int 13h contains mainly BIOS drive functions)
    ret

----xkernel.asm----
[BITS 16]                ; try with bits 32

    jmp short start

; Variables

%include "common.inc"
    os_info                db 'XOS, ver 0.06, by XezzeX @ 12/05-2005',13,10,0
    os_bootmsg                db 'Booting XezzeXOS ...',13,10,0
    os_rebootmsg            db 'You have chosen to reboot!',13,10,'Press any key to reboot!',13,10,0

; Code

start:
    ; enter protected mode
    ; init external devices    ->    fdd,hdd,cdrom,audio,graphics,
    ; load "bash"-like prompt

    mov si, os_info            ; write OS info to screen
    call print_string

    mov si, os_bootmsg
    call print_string

wait_for_key:

    call read_char
    call print_char
    cmp al,0Dh                ; 0Dh=<Enter>
    jz reboot                ; if true jumpto reboot
    jmp wait_for_key            ; loops forever (simulates something "bash"-like *GG*)
                        ; the mission is to make this bootstrap load a kernel, which loads "bash"-like prompt

reboot:
    mov si,os_rebootmsg
    call print_string
    call read_char
    jmp 0xFFFF:0x0000            ; reboots the machine