Problematic Code

BITS 16
ORG 32768

b0 db 0
b1 db 0
b2 db 0
b3 db 0
w0 dw 0
w1 dw 0
w2 dw 0
w3 dw 0
d0 dd 0
d1 dd 0
d2 dd 0
d3 dd 0
s0 resb 256
s1 resb 256
s2 resb 256
s3 resb 256
%DEFINE addr $
os_cls equ 0009h
os_prnt equ 0003h
os_cursmov equ 0006h
os_prnthl equ 000Ch
os_prntnl equ 000Fh
os_drawbg equ 002Ah
os_getstr equ 0036h

cls:
call os_cls
ret

prnt:
mov ax, word [w0]
call os_prnt
ret

cursmov:
mov dh, byte [b0]
mov dl, byte [b1]
call os_cursmov
ret

prnthl:
mov ax, byte [b0]
call os_prnthl
ret

prntnl:
call os_prntnl
ret

drawbg:
mov ax, word [w0]
mov bx, word [w1]
mov cx, word [w2]
call os_drawbg
ret

getstr:
mov ax, word [w0]
call os_getstr
ret