东南大学信息学院微机实验报告九

1、实验九一、实验目的熟悉系统功能调用INT21H的有关功能1. 编写时钟程序二、实验任务1. 执行时钟程序时，屏幕上显示提示符“：随即显示时间并不停地计时。2. 当有键盘按下时，立即停止计时，返回三、源程序DATASEGMENTBUFFERDB11DB?DB10DUPDATAENDSCODESEGMENTASSUMECS:CODE,DS:DATAOUTCLK:MOVAX,DATAMOVDS,AXMOVDL,':'MOVAH,2INT21HMOVDX,OFFSETBUFFERMOVAH,0AH;INT21HMOVBX,OFFSETBUFFER+2MOVAL,BX;CMPAL,03A

2、HJAEERROR1CMPAL,02FHJBEERROR1ANDAL,0FHMOVBX,ALINCBXMOVAL,BXANDAL,0FHMOVBX,ALINCBXINCBXMOVAL,BX;ANDAL,0FHMOVBX,ALINCBX”，由键盘输入当前时、分、秒值，即DOS输入字符串时针，ASCII码转非压缩BCD分针XX:XX:XXMOVAL,BXANDAL,0FHMOVBX,ALINCBXINCBXMOVAL,BX;秒针ANDAL,0FHMOVBX,ALINCBXMOVAL,BXANDAL,0FHMOVBX,ALMOVBX,OFFSETBUFFER+2CALLTOBCDMOVCH,ALAD

3、DBX,3CALLTOBCDMOVDH,ALMOVDH,ALADDBX,3CALLTOBCDMOVDL,ALCMPCH,24HJAEERRORCMPDH,60HJAERRORCMPDL,60HJAERRORERROR1:MOVAH,4CHINT21HAGAIN:CALLDELAYMOVAL,DLADDAL,1DAAMOVDL,ALCMPAL,60HJAERRORJNEDISPYMOVDL,0MOVAL,DHADDAL,1DAAMOVDH,ALCMPAL,60H时针，两位非压缩分针，两位非压缩秒针，两位非压缩秒针加1分针BCD转换成两位压缩BCDBCD转换成两位压缩BCDBCD转换成两位压缩BC

4、DJAERRORJNEDISPYMOVDH,0MOVAL,CHADDAL,1时针DAA;MOVCH,ALCMPAL,24HJAEERRORJNEDISPYMOVCH,0ERROR:MOVDL,0MOVDH,0MOVCH,0DISPY:MOVBX,OFFSETBUFFERMOVAL,0DHMOVBX,ALINCBXMOVAL,0MOVBX,ALINCBXMOVAL,CHCALLTRANINCBXMOVAL,':'MOVBX,ALINCBXMOVAL,DHCALLTRANINCBXMOVAL,':'MOVBX,ALINCBXMOVAL,DLCALLTRANINCBX

5、MOVAL,'$'MOVBX,ALPUSHBXPUSHCXPUSHDXMOVDX,OFFSETBUFFERMOVAH,9INT21HMOVAH,06HMOVDL,0FFHINT21HPOPDXPOPCXPOPBXJNEGOJMPAGAINGO:MOVAH,4CHINT21HTOBCDPROC;两位非压缩BCD转换成压缩MOVAL,BXMOVCL,4SHLAL,CLORAL,BX+1RETTOBCDENDPTRANPROC;BCD转ASCIIMOVCL,ALSHRAL,1SHRAL,1SHRAL,1SHRAL,1ORAL,30HMOVBX,ALINCBXMOVAL,CLANDAL,0FHORAL,30HMOVBX,ALRETTRANENDPDELAYPROCPUSHCXPUSHAXMOVAX,0FFFFHFIR:MOVCX,02FFFHGOON:DECCXJNEGOONDECAXJNEFIRPOPAXPOPCXRETDELAYENDPCODEENDSENDOUTCLK四、思考题时钟程序中存在误差吗？若有误差，其来源在何处？如何进行误差矫正