---

in ax, 2
mov bx, ax
and bx, 7Fh
mov cx, ax
shr cx, 12
and cx, 0Fh
mov dx, ax
shr dx, 7
and dx, 1Fh
cmp cx, 0
jz zero
mov ax, bx
xor dx, dx
div cx
sub ax, dx
jmp res
zero:
xor ax, ax
res:
out 3, ax