[BITS 16] ; Code für 16 - Bit - Mode generieren
  ; Alexander Aigner, sib1310239002

  org 0x7C00 ; Startoffset
  start: ; Label "start"
    xor ax, ax ; ax = 0
    mov fs, ax ; ds = 0
    mov bx, 0x80 ; 0x80 = Addresse Interrupt 20
    ; register interrupt
    mov word [fs:bx], ISR20H
    mov word [fs:bx+2], 0

    int 0x20 ; Interrupt 20 Testen

  jmp $ ; Endlosschleife

; Data
ISR20H:
    ; get cursor position
    mov ah, 0x03
    int 0x10
    ; write string
    mov ax, isrmsg
    mov bp, ax ; String offset = bsy1msg
    xor ax, ax
    mov es, ax ; = 0
    mov cx, isrlen ; String len
    mov bx, 0x001F ; Set video page/text attribute
    mov ax, 0x1301 ; Mode = Wite String, move Cursor
    int 0x10
iret

; ISR Data
isrmsg: db "ISR20h"
isrlen: equ $ - isrmsg