【正文】 。起步公里顯示, 起步公里數(shù)存儲在 ACALL CHE MOV A,41H ADD A,0AH MOV 43H,A MOV A,33H ACALL CHE MOV 52H,1BH 。送入顯示緩沖區(qū) MOV 53H,1BH 。初始顯示 MOV 54H,1BH MOV 55H,1BH MOV 56H,1BH MOV 57H,43H MOV 58H,42H MOV 59H,41H ACALL DIR 。調(diào)用顯示子程序 RETDANJIA: MOV A,34H 。單價顯示, 單價存儲在34H,35H單元 ACALL CHE MOV A,41H ADD A,0AH MOV 43H,A MOV A,35H ACALL CHE MOV 52H,1BH 。送入顯示緩沖區(qū) MOV 53H,1BH 。 初始顯示 MOV 54H,1BH MOV 55H,1BH MOV 56H,1BH MOV 57H,43H MOV 58H,42H MOV 59H,41H ACALL DIR 。調(diào)用顯示子程序 RETLC_XS: MOV A,36H 。總路程顯示，總路程存儲在36H,37H,38H ACALL CHE MOV 46H,42H MOV 45H,41H MOV A,37H ACALL CHE MOV 44H,42H MOV A,41H ADD A,0AH MOV 43H,A MOV A,38H ACALL CHE MOV 52H,15H 。送入顯示緩沖區(qū) MOV 53H,1AH 。 初始顯示L= MOV 54H,46H MOV 55H,45H MOV 56H,44H MOV 57H,43H MOV 58H,42H MOV 59H,41H ACALL DIR 。調(diào)用顯示子程序 RETJE_XS: MOV A,39H ?？偨痤~顯示，存儲在39H,3AH,3BH單元 ACALL CHE MOV 46H,42H MOV 45H,41H MOV A,3AH ACALL CHE MOV 44H,42H MOV A,41H ADD A,0AH MOV 43H,A MOV A,3BH ACALL CHE MOV 52H,14H 。送入顯示緩沖區(qū) MOV 53H,1AH 。初始顯示P= MOV 54H,46H MOV 55H,45H MOV 56H,44H MOV 57H,43H MOV 58H,42H MOV 59H,41H ACALL DIR 。調(diào)用顯示子程序 RETSHIJIAN: MOV IE,88H CLR TR0 SETB TR1 MOV A,3EH ?？偨痤~顯示，存儲在39H,3AH,3BH單元 ACALL CHE MOV 46H,42H MOV 45H,41H MOV A,3DH ACALL CHE MOV 44H,42H MOV A,41H MOV 43H,A MOV A,3CH ACALL CHE MOV 52H,05H 。送入顯示緩沖區(qū) MOV 53H,1AH 。初始顯示P= MOV 54H,46H MOV 55H,45H MOV 56H,44H MOV 57H,43H MOV 58H,42H MOV 59H,41H ACALL DIR 。調(diào)用顯示子程序 RETCJH: MOV B,A 。保存，求鍵號子程序 MOV R2,00H 。00放項號 MOV R7,0FH 。循環(huán)15次CJH1: MOV A,R2 ADD A,0AH 。查表 MOVC A,@A+PC CJNE A,B,CJH2 。A，B不等轉(zhuǎn)CJH2 SJMP CJH3CJH2:INC R2 DJNZ R7,CJH1CJH3: MOV A,R2 RETTABR: DB 1FH,1EH,1DH,1CH,17H,16H,15H,14H,0FH DB 0EH,0DH,0CH,07H,06H,05H,04HLUC: CLR C 。LUC為T0中斷子程序 MOV A,38H ADD A,01H 。每有1個脈沖到來38H加1， DA A MOV 38H,A MOV A,37H ADDC A,00H 。有進(jìn)位，往個位和十位進(jìn)位 DA A MOV 37H,A MOV A,36H ADDC A,00H 。檢查有無進(jìn)位，往百位進(jìn) DA A MOV 36H,A CJNE A,10H,LUC0 CPL TR0LUC0: MOV A,38H 。39H－3BH單元存儲總金額 CLR C SUBB A,33H 。比較是否超過起步公里數(shù) MOV A,37H SUBB A,32H MOV A,36H SUBB A,00H JNB , LUC1 。超過起步公里L(fēng)UC1 LJMP LUC2LUC1: MOV A,38H CJNE A,00H,LUC2 MOV A,35H 。超過起步公里數(shù)，按單價累加(單價存儲在34H35H) ADD A,3BH DA A MOV 3BH,A MOV A,34H ADDC A,3AH 。有進(jìn)位，向總金額的個位和十位進(jìn)位 DA A MOV 3AH,A MOV A,39H ADDC A,00H 。有進(jìn)位，向總金額的百位進(jìn) DA A MOV 39H,A LUC2: JNB 00H,LC_11 。檢查總路程或總金額的標(biāo)志位 LCALL LC_XS 。顯示總路程 LJMP LP1111LC_11: LCALL JE_XS 。顯示總金額 LCALL DIR LP1111: RETIYY: MOV TH1,00H 。TR1中斷服務(wù)程序 MOV TL1,00H MOV A,3CH ADD A,01H 。每有1個脈沖到來38H加1， DA A MOV 3CH,A MOV A,3DH ADDC A,00H 。有進(jìn)位，往個位和十位進(jìn)位 DA A MOV 3DH,A MOV A,3EH ADDC A,00H 。檢查有無進(jìn)位，往百位進(jìn) DA A MOV 3EH,A MOV A,35H 。超過起步公里數(shù)，按單價累加(單價存儲在34H35H) ADD A,3BH DA A MOV 3BH,A MOV A,00H ADDC A,3AH 。有進(jìn)位，向總金額的個位和十位進(jìn)位 DA A MOV 3AH,A MOV A,39H ADDC A,00H 。有進(jìn)位，向總金額的百位進(jìn) DA A MOV 39H,A LUC2S: JNB 30H,LC_11S 。檢查總路程或總金額的標(biāo)志位 LCALL SHIJIAN 。顯示總路程LJMP LP11111LC_11S: LCALL JE_XS 。顯示總金額 LCALL DIR LP11111: RETIEND附錄二 元件清單 元器件名型號數(shù)量7279最小系統(tǒng)板HD72791電阻1KΩ1電阻1電容2芯片NE5551電位器100K2電容10uf