TITLE PROGRAM 4-6: MODIFIED VERSION OF PROGRAM 4-5
;THIS PROGRAM SOUNDS THE BELL CONTINUOUSLY UNTIL 'Q' OR 'q' IS PRESSED
          .MODEL SMALL
          .STACK
          .DATA
MESSAGE DB  'TO STOP THE BELL SOUND PRESS Q (or q) KEY$'

          .CODE
MAIN      PROC
          MOV     AX,@DATA
          MOV     DS,AX
          MOV     AH,09
          MOV     DX,OFFSET MESSAGE   ;DISPLAY THE MESSAGE
          INT     21H
AGAIN:    MOV     AH,02                      
          MOV     DL,07             ;SOUND THE BELL BY SENDING OUT BELL CHAR 
          INT     21H
          MOV     AH,01             ;CHECK FOR KEY PRESS
          INT     16H               ;USING INT 16H
          JZ      AGAIN             ;IF NO KEY PRESS KEEP SOUNDING THE BELL
          MOV     AH,0              ;TO GET THE CHARACTER 
          INT     16H               ;WE MUST USE INT 16H ONE MORE TIME
          JE      EXIT              ;IF YES EXIT
          CMP     AL,'q'            ;IS IT 'q'
          JE      EXIT              ;IF YES EXIT
          JMP     AGAIN             ;NO. KEEP SOUNDING THE BELL
EXIT:     MOV     AH,4CH            ;GO BACK TO DOS
          INT     21H
MAIN      ENDP
          END