東南大學(xué)信息學(xué)院微機(jī)實(shí)驗(yàn)報告九

1、精選優(yōu)質(zhì)文檔-傾情為你奉上實(shí)驗(yàn)九一、實(shí)驗(yàn)?zāi)康?.熟悉系統(tǒng)功能調(diào)用INT 21H的有關(guān)功能2.編寫時鐘程序二、實(shí)驗(yàn)任務(wù)1.執(zhí)行時鐘程序時，屏幕上顯示提示符“：”，由鍵盤輸入當(dāng)前時、分、秒值，即XX:XX:XX，隨即顯示時間并不停地計(jì)時。2.當(dāng)有鍵盤按下時，立即停止計(jì)時，返回DOS。三、源程序DATA SEGMENTBUFFER DB 11 DB ? DB 10 DUP(?)DATA ENDSCODE SEGMENT ASSUME CS:CODE,DS:DATAOUTCLK: MOV AX,DATA MOV DS,AX MOV DL,':' MOV AH,2 INT 21H MOV

2、 DX,OFFSET BUFFER MOV AH,0AH ;輸入字符串 INT 21H MOV BX,OFFSET BUFFER+2 MOV AL,BX ; 時針，ASCII碼轉(zhuǎn)非壓縮BCD CMP AL, 03AH JAE ERROR1 CMP AL, 02FH JBE ERROR1 AND AL,0FH MOV BX,AL INC BX MOV AL,BX AND AL,0FH MOV BX,AL INC BX INC BX MOV AL,BX ; 分針 AND AL,0FH MOV BX,AL INC BX MOV AL,BX AND AL,0FH MOV BX,AL INC BX IN

3、C BX MOV AL,BX ;秒針 AND AL,0FH MOV BX,AL INC BX MOV AL,BX AND AL,0FH MOV BX,AL MOV BX,OFFSET BUFFER+2 CALL TOBCD ; 時針，兩位非壓縮BCD轉(zhuǎn)換成兩位壓縮BCD MOV CH, AL ADD BX,3 CALL TOBCD MOV DH, AL ; 分針，兩位非壓縮BCD轉(zhuǎn)換成兩位壓縮BCD MOV DH,AL ADD BX,3 CALL TOBCD ; 秒針，兩位非壓縮BCD轉(zhuǎn)換成兩位壓縮BCD MOV DL,AL CMP CH, 24H JAE ERROR CMP DH, 60H

4、JA ERROR CMP DL, 60H JA ERRORERROR1: MOV AH,4CH INT 21H AGAIN: CALL DELAY MOV AL,DL ; 秒針加1 ADD AL,1 DAA MOV DL,AL CMP AL,60H JA ERROR JNE DISPY MOV DL,0 MOV AL,DH ADD AL,1 ; 分針 DAA MOV DH,AL CMP AL,60H JA ERROR JNE DISPY MOV DH,0 MOV AL,CH ADD AL,1 DAA ; 時針 MOV CH,AL CMP AL,24H JAE ERROR JNE DISPY M

5、OV CH,0ERROR: MOV DL, 0 MOV DH, 0 MOV CH, 0DISPY: MOV BX,OFFSET BUFFER MOV AL,0DH MOV BX,AL INC BX MOV AL,0 MOV BX,AL INC BX MOV AL,CH CALL TRAN INC BX MOV AL,':' MOV BX,AL INC BX MOV AL,DH CALL TRAN INC BX MOV AL,':' MOV BX,AL INC BX MOV AL,DL CALL TRAN INC BX MOV AL,'$' MOV

6、 BX,AL PUSH BX PUSH CX PUSH DX MOV DX,OFFSET BUFFER MOV AH,9 INT 21H MOV AH,06H MOV DL,0FFH INT 21H POP DX POP CX POP BX JNE GO JMP AGAINGO: MOV AH,4CH INT 21HTOBCD PROC ; 兩位非壓縮BCD轉(zhuǎn)換成壓縮 MOV AL,BX MOV CL,4 SHL AL,CL OR AL,BX+1 RETTOBCD ENDPTRAN PROC ; BCD轉(zhuǎn)ASCII MOV CL,AL SHR AL,1 SHR AL,1 SHR AL,1 SHR AL,1 OR AL,30H MOV BX,AL INC BX MOV AL,CL AND AL,0FH OR AL,30H MOV BX,AL RETTRAN ENDPDELAY PROC PUSH CX PUSH AX MOV AX,0FFFFHFIR: MOV CX,02FFFHGOON: DEC CX JNE GOON DEC AX JNE FIR POP AX POP CX RETDELAY ENDPCODE ENDSEND OUTCLK四、思考題時鐘程序中存在誤差嗎？若有誤差，其來源