sound2.asm

用8253编制秒表延迟程序

data  segment
      a1    db 'hello!',0dh,0ah,'$'
data  ends	
code  segment
       assume  cs:code,ds:data
 start:mov    ax,data
       mov    ds,ax
       mov    dx,offset a1
       mov    ah,09h
       int    21h 
 W1:   MOV    AH,0BH         ;有键按下?
       INT    21H
       CMP    AL,00H         ;无键按下,转W1,否则,调用发声程序 
       JZ     W1             
 SING: MOV    BL,0FFH
       call   sound
       MOV    AH,0BH
       INT    21H
       CMP    AL,00H          ;有键按下?
       JZ     SING            ;无键按下,转SING 
       MOV    AH,08H
       INT    21H
       CMP    AL,1BH         ;有键按下,是ESC键?
       JNZ    SING           ;是,退出,否,转SING
       mov    ah,4ch
       int    21h
;---------sound-------
sound  proc   near
       push   ax
       push   bx
       push   cx
       mov    al,0b6h
       out    43h,al
       MOV    AX,1983
       out    42h,al
       mov    al,ah
       out    42h,al
       in     al,61h       ;read PB
       mov    ah,al
       OR     al,00000011B       ;开发声器
       out    61h,al
          SUB   CX,CX          ;置CX=65536
      LOP:  loop  LOP
          dec   BL
          jnz   LOP
        mov al,0
	out 61h,al  
	mov   al,ah
          out   61h,al
	  pop   cx
	  pop   bx
          pop   ax	  
             ret
  sound  endp                   
code   ends
       end start