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1、汇编小程序：小写字母转换成大写字母实验内容：接收键入字符（以CTRL-C为结束），将小写字母变为大写字母，并在屏幕上显示。DATASSEGMENTMESSAGEDB'Welcometothesystem!',13,10,13,10DB'Thefunctionoftheprogramischangingsmallletterstocapitalletters.',13,10DB'Ifyouentercapitallettersornumberstherewillbenochanges.',13,10,13,10DB'Pleaseenterastring.',13,10,'$'C
2、RDB13,10,'$';回车换行STRINGDB100DB0DB80DUP(0);定义缓冲区AGAINDB'Doyouwanttotryagain?(YorN)',13,10,'$'ERRORDB'ERROR!',13,10,'Pleaseentertherightcommomds.',13,10,'$';错误提示DATASENDSSTACKSSEGMENTDB200DUP(?)STACKSENDSCODESSEGMENTASSUMECS:CODES,DS:DATAS,SS:STACKSSTART:HEAD:MOVAX,DATASMOVDS,AXLEADX,MESSAGE;
3、输出提示语MOVAH,09HINT21HLEADX,STRINGMOVAH,0AHINT21H;把字符串输入到BUF区LEADX,CRMOVAH,09HINT21H;以上为回车换行LEASI,STRING+2;把字符串首地址存入BXMOVCL,STRING+1;把字符个数存CXMOVCH,0NEXT1:MOVDL,[SI]CMPDL,'a'JBNEXT2CMPDL,'z'JANEXT2;ASCII码小于a和大于z的跳过，其余的减32SUBDL,20H;大小写字母的ASCII码差32NEXT2:MOVAH,02HINT21HINCSI;BX自加，判断下一个字符DECCX;CX自
4、减，最终将是0JNENEXT1;CX非零时，跳回NEXT1MOVDX,OFFSETCR;输出回车换行MOVAH,09HINT21HJMPEXITOVERFLOW:;错误提示LEADX,CRMOVAH,09HINT21HLEADX,ERRORMOVAH,09HINT21HEXIT:LEADX,CRMOVAH,09HINT21HLEADX,AGAIN;提示是否再试一次MOVAH,09HINT21HMOVAH,01HINT21HPUSHAXLEADX,CRMOVAH,09HINT21HPOPAXCMPAL,'Y'JZHEADCMPAL,'y'JZHEADCMPAL,'N'JZOVE
5、RCMPAL,'n'JZOVERJMPOVERFLOWOVER:MOVAH,4CHINT21HCODESENDSENDSTART;如果需要把大写字母转乘小写的，只要把代码中-20H变为+20H即可
