model  SMALL
        stack  100

        dataseg
MAX	db ?
MB      db     4,7,11,23,5

        codeseg
        startupcode

        lea    BX, MB    
        mov    CX, 5    
BEG:
        mov    AL, [BX]
	mov    DL, [BX]
	and    AL, 240
	shr    AL, 4
	and    DL, 15
	xor    AL, DL
	mov    [BX], AL
        add    BX, 1
        loop   BEG 
	mov    CX, 4
	mov    AL, [BX]
	mov    BX,0
        	
	BEGIN:
        xor AL, [BX+1]
	add BX, 1
	loop BEGIN
	 
QUIT:   exitcode  0
        end