stack segment stack
db 100h dup(0)
stack ends

data segment
x db 1h
y db 2h
data ends

code segment
assume cs:code,ds:data,ss:stack
start:
mov ax,data
mov ds,ax
mov al,x
mov bl,y
add al,bl
mov dl,al
mov ah,2h
int 21h
mov ah,4ch
int 21h
code ends
end start