stack segment stack'stack'
      dw 32 dup(?)
stack ends
data segment
BVAR DB 36H
data ends
code segment
begin proc far
      assume ss:stack,cs:code,ds:data
      push ds
      sub ax,ax
      push ax
      mov ax,data
      mov ds,ax
      MOV AL,BVAR
      MOV CL,4
      SHR AL,CL
      MOV BL,10
      MUL BL
      AND BVAR,0FH
      ADD AL,BVAR
      MOV BVAR,AL
      ret
begin endp
code ends
     end begin