boot.asm

org 0x7c00
bits 16
start:
    call cls
    mov bx, display
print:
    mov al, [bx]
    cmp al, 0
    je halt
    call print_char
    inc bx
    jmp print
print_char:
    mov ah, 0x0e
    int 0x10
    ret
halt:
    ret
cls:
    mov ah, 0x07
    mov al, 0x00
    mov bh, 0x02
    mov cx, 0x00
    mov dx, 0x184f
    int 0x10
    ret
display db "MBR doomed", 13, 10, 0
times 510 - ($ - $$) db 0
dw 0xaa55