SET8255: MOV DPTR,#8003H
         MOV A,#80H
         MOVX @DPTR,A
  START1:
         LCALL KEYPLAY
         JMP START1     
KEYPLAY:
KEYBORAD:MOV R0,#70H
KEY1:   ACALL KS1
        JNZ LK1
KEY2:   ACALL TM6ms
        RET
LK1:    ACALL TM12ms
        ACALL KS1
        JNZ LK2
        AJMP KEY2
LK2:    MOV R2,#0FFH     ;ZU HANG SAOMIAO
        MOV R4,#00H
LK4:    MOV DPTR,#8000H
        MOV A,R2
        MOVX @DPTR,A
        INC DPTR
        INC DPTR
        MOVX A,@DPTR
        JB ACC.0,LONE    ;cha di yi hang
        MOV A,#00H        ;  #00-a
        AJMP LKP          ;
LONE:   JB ACC.1,LTWO
        MOV A,#04H
        AJMP LKP
LTWO:   JB ACC.2,LTHR
        MOV A,#08H
        AJMP LKP
LTHR:   JB ACC.3,NEXT
        MOV A,#0CH
LKP:    ADD A,R4          ;qiu jian ma
        ACALL KEYIN
        PUSH ACC
LK3:    ACALL KS1         ;deng jian shi fang
        JNZ LK3
        POP ACC
        RET
NEXT:   INC R4
        MOV A,R2
        AJMP LK4
KEND:   AJMP KEY1
KEYIN:  MOV   DPTR,#KEYTAB
        MOVC  A,@A+DPTR
        MOV   @R0,A
        INC  R0
        RET
KS1:    MOV DPTR,#8000H   ;判斷有無鍵按下
        MOV A,#00H
        MOVX @DPTR ,A
        INC DPTR
        INC DPTR
        MOVX A,@DPTR
        CPL A
        ANL A,#0FH      ;A=/0有間暗下
        RET
TM12ms: MOV R7,#18
TM:     MOV R6,#0FFH
TM6:   DJNZ R6,TM6
        DJNZ R7,TM
        RET
TM6ms:  MOV R7,#0CH
TM2:    MOV R6,#0FFH
TM62:   DJNZ R6,TM62
        DJNZ R7,TM
        RET
KEYTAB: DB 00H,0FH,0EH,0DH
        DB 01H,02H,03H,0CH
        DB 04H,05H,06H,0BH
        DB 07H,08H,09H,0AH