NAME    T13F                ;雙機通訊實驗(發送程序)
CSEG    AT    0000H
        LJMP  START
CSEG    AT    4100H
PORT    EQU   0CFE8H
START:  MOV   DPTR,#PORT+1  ;8279命令字
        MOV   A,#0D1H       ;清除
        MOVX  @DPTR,A
WAIT:   MOVX  A,@DPTR
        JB    ACC.7,WAIT    ;等待清除完畢
        MOV   TMOD,#20H
        MOV   TH1,#0F2H
        MOV   TL1,#0F2H
        SETB  TR1
        MOV   SCON,#50H
        MOV   87H,#80H
        MOV   50H,#00H
        MOV   51H,#00H
        MOV   52H,#00H
        MOV   53H,#00H
        MOV   54H,#00H
        MOV   55H,#00H
LOOP1:  MOVX  A,@DPTR
        ANL   A,#0FH
        JZ    LOOP1         ;有鍵按下?
        MOV   A,#0A0H       ;顯示消隱命令
        MOVX  @DPTR,A
        MOV   DPTR,#PORT    ;讀鍵值
        MOVX  A,@DPTR
        ANL   A,#3FH
        MOV   R7,A          ;狀態保存
        MOV   50H,51H
        MOV   51H,52H
        MOV   52H,53H
        MOV   53H,54H
        MOV   54H,55H
LOP:    MOV   A,R7
        MOV   DPTR,#TAB1
        MOVC  A,@A+DPTR     ;查取數字鍵的字型碼
        MOV   55H,A
        mov   40h,a
        SUBB  A,#80H
        JZ    ERROR         ;非數字鍵則跳轉
        ACALL DISP
        SJMP  TXACK
DISP:   MOV   DPTR,#PORT+1
        MOV   A,#90H
        MOVX  @DPTR,A
        MOV   R6,#06H
        MOV   R1,#50H
        MOV   DPTR,#PORT
DL0:    MOV   A,@R1
        MOVX  @DPTR,A
        INC   R1
        DJNZ  R6,DL0
        RET
TXACK:  MOV   A,#06H        ;發呼叫信號"06"
        MOV   SBUF,A
WAIT1:  JBC   TI,RXYES      ;等待發送完一個字節
        SJMP  WAIT1
RXYES:  JBC   RI,NEXT1      ;等待乙機回答
        SJMP  RXYES
NEXT1:  MOV   A,SBUF        ;判斷乙機是否同意接收,不同意繼續呼叫
        CJNE  A,#00H,TXACK
        MOV   A,40H
        MOV   SBUF,A
WAIT2:  JBC   TI,TXNEWS
        SJMP  WAIT2
TXNEWS: JBC   RI,IF0DDH
        SJMP  TXNEWS
IF0DDH: MOV   A,SBUF
        CJNE  A,#0FH,TXACK ;判斷乙機是否接收正確,不正確繼續呼叫
        MOV   DPTR,#0CFE9H
        LJMP  LOOP1
ERROR:  MOV   50H,#79H
        MOV   51H,#31H
        MOV   52H,#31H
        MOV   53H,#5CH
        MOV   54H,#31H
        MOV   55H,#80H
        LCALL DISP
DD:     MOV   DPTR,#PORT+1
        MOVX  A,@DPTR
        ANL   A,#0FH
        JZ    DD            ;有鍵按下?
        MOV   A,#0A0H       ;顯示消隱命令
        MOVX  @DPTR,A
        MOV   DPTR,#0CFE8H  ;讀鍵值
        MOVX  A,@DPTR
        ANL   A,#3FH
        MOV   R7,A          ;狀態保存
        MOV   50H,#00H
        MOV   51H,#00H
        MOV   52H,#00H
        MOV   53H,#00H
        MOV   54H,#00H
        LJMP  LOP
TAB1:   DB 3FH,06H,5BH,4FH,80H,80H  ;鍵值字型碼表
        DB 66H,6DH,7DH,07H,80H,80H
        DB 7FH,6FH,77H,7CH,80H,80H
        DB 39H,5EH,79H,71H,80H,80H
        DB     80H,80H,80H,80H
END