data segment
        x dw 1122h
        y dw 3344h
        z dw ?
data ends
code segment
         assume cs:code,ds:data
main proc far
start:push ds
        xor ax,ax
        push ax
        mov ax,data
        mov ds,ax
        mov ax,x
        add ax,y
        mov z,ax
        ret
main endp
code ends
        end start