data segment freq dw 262,294,330,349,392l,440,494 data ends code segment assume ds:data, cs:code main proc far start： push ds mov ax,0 push ax mov ax,data mov ds,ax mov al,10110110b ;8253定時器2初始化 out 43h, al in al,61h ;讀pb口 or al,03h out 61h,al ；pb0, pb1=’1’, 打開聲音 again： mov ah, 1 ；dos功能調(diào)用，鍵盤