KEY1:  ACALL  KS1
       JNZ  LK1  ；不為0，有鍵盤按下，轉(zhuǎn)
       ACALL DIS  ；調(diào)用顯示子程序，延時6MS
       AJMP  KEY1
LK1:   ACALL   DIS ；調(diào)用顯示子程序，延時12Ms
       ACALL   DIS
       ACALL   KS1
       JNZ    LK2
       ACALL  DIS   ；調(diào)用顯示子程序，延時6MS
       AJMP   KEY1
LK2:   MOV  R2,#11111011B
       MOV  R4,#00H   ；從第0列開始，4*4鍵盤顯示
LK4:   MOV  DPTR,#8002H  ；位選
       MOV  A,R2
       MOVX @DPTR,A
       MOV DPTR ,#8001H  ；鍵盤輸入
       MOVX A,@DPTR
       JB ACC.0,LONE  ；第0行
       MOV A,#00H
       AJMP  LKP
LONE:  JB acc.1,LTWO
       MOV A,#04H  ；第1行
       AJMP LKP
LTWO:  JB ACC.2,LTHR
       MOV A,#08H  ；第2行
       AJMP LKP
LTHR:JB ACC.3,NEXT
     MOV A,#0CH  ；第3行
LKP: ADD A,R4
     PUSH ACC
LK3: ACALL DIS
     ACALL KS1
     JNZ   LK3
     POP   ACC
     MOV 7BH,7AH
     MOV 7AH,79H
     MOV 79H,78H
     MOV 78H,A
     SJMP    KEY1;RET
NEXT: INC  R4  ；下一列
      MOV A,R2
      JNB ACC.5,KND
      RL A
      MOV R2,A
      AJMP LK4
KND:  AJMP KEY1
KS1:  MOV DPTR ,#8002H  ；判斷是否有鍵盤按下
      MOV A,#00H
      MOVX @DPTR,A
      MOV DPTR, #8001H
      MOVX A,@DPTR
      CPL A
      ANL A,#0FH
      RET

DIS: MOV R0,#78H  ；動態(tài)顯示子程序
     MOV R3,#00000100B
     MOV A,R3
LD0: MOV DPTR,#8002H  ；位選
     MOVX @DPTR,A
     MOV DPTR,#8004H ；段選
     MOV A,@R0
     ADD A,#0DH
     MOVC A,@A+PC
     MOVX @DPTR,A
     ACALL DL1
     INC R0
     MOV A,R3
     JB ACC.5,LD1
     RL  A
     MOV R3,A
     AJMP LD0
LD1: RET
DSEG:    DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH,77H,7CH,39H,5EH,79H,71H  ;共陰表

DL1: MOV R7,#02H  ；延時子程序
DL:  MOV R6,#0FFH
DL6: DJNZ R6,DL6
     DJNZ R7,DL
     RET