datasegmentfreqdw262,294,330,349,392l,440,494dataendscodesegmentassumeds:data,cs:codemainprocfarstart：pushdsmovax,0pushaxmovax,datamovds,axmoval,10110110b;8253定时器2初始化out43h,alinal,61h;读pb口oral,03hout61h,al；pb0,pb1=’1’,打开声音again：movah,1；dos功能调用，键盘输入并回显int21h；按键（键入的ascii码值在al中）
