Simple Bootloader

;simple bootloader:

;puts data space for stack
mov ax, 9ch
mov ss, ax ;define where stack exists
mov sp, 4096d ;define size of stack
mov ax, 7c0h
mov ds, ax

;-code for OS:---------
mov ah, 0eh ;print key from hex value
mov al, 37h ;7 key
int 10h
jmp $ ;endless loop

;---------------
times 510-($-$$) db 0 ;zeros rest of fdd memory
dw 0xAA55 ;boot signature