NAME    T13J                ;雙機通訊實驗
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     ;初始化定時器
        MOV   TL1,#0F2H
        SETB  TR1
        MOV   SCON,#50H     ;初始化串行口
        MOV   87H,#80H
        MOV   50H,#00H
        MOV   51H,#00H
        MOV   52H,#00H
        MOV   53H,#00H
        MOV   54H,#00H
        MOV   55H,#00H
        SJMP  RXACK
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
RXACK:  JBC   RI,IF06H      ;接收呼叫信號
        SJMP  RXACK
IF06H:  MOV   A,SBUF        ;判斷呼叫是否有誤
        CJNE  A,#06H,TX15H
TX00H:  MOV   A,#00H
        MOV   SBUF,A
WAIT1:  JBC   TI,RXBYTES    ;等待應答信號發送完
        SJMP  WAIT1
TX15H:  MOV   A,#0F0H       ;向甲機報告接收的呼叫信號不正確
        MOV   SBUF,A
WAIT2:  JBC   TI,HAVE1
        SJMP  WAIT2
HAVE1:  SJMP  RXACK
RXBYTES:JBC   RI,HAVE2
        SJMP  RXBYTES
HAVE2:  MOV   A,SBUF
        MOV   R7,A
        MOV   A,#0FH
        MOV   SBUF,A
WAIT3:  JBC   TI,LOOP1
        SJMP  WAIT3
LOOP1:  MOV   DPTR,#PORT+1
        MOV   A,#0A0H       ;顯示消隱命令
        MOVX  @DPTR,A
        MOV   50H,51H
        MOV   51H,52H
        MOV   52H,53H
        MOV   53H,54H
        MOV   54H,55H
        MOV   A,R7
        MOV   55H,A
        LCALL DISP
        LJMP  RXACK
END