从机串行口多机通信.asm

这个是大学的计算机接口实验课上经常用到的原程序

         ORG    0000H
MAIN:    MOV    TMOD,#20H
         MOV    TH1, #0F3H
         MOV    TL1, #0F3H
         MOV    SCON,#0F0H
         MOV    PCON,#80H
         MOV    R0,  #30H
         MOV    R1,  #40H
         MOV    R2,  #0AH
         SETB   TR1
S1:      JBC    RI,  S2
         AJMP   S1
S2:      MOV    A ,  SBUF
         CLR    RI
         CJNE   A,50H,S1
         CLR    SM2
         MOV    SBUF,A
S3:      JBC    TI,  S4
         SJMP   S3
S4:      CLR    TI
S5:      JBC    RI,  S6
         SJMP   S5
S6:      CLR    RI
         MOV    A,  SBUF
         CJNE   A,   #01H,LOOP1
         AJMP   RDX1
LOOP1:   CJNE   A,   #02H,ERR1
         AJMP   RDX1
ERR1:    MOV    A,  #80H
         MOV    SBUF,A
S7:      JBC    TI,  S8
         SJMP   S7
S8:      CLR    TI
         SETB   SM2
         LJMP   S1
TDX1:    MOV    A ,  R2
         MOV    SBUF,A
S9:      JBC    TI,  S10
         SJMP   S9
S10:     CLR    TI
LOOP2:   MOV    A,   @R0
         MOV    SBUF,A
S11:     JBC    TI,  S12
         SJMP   S11
S12:     CLR    TI
         INC    R0
         DJNZ   R2, LOOP2
         LJMP   MAIN
RDX1:    JBC    RI,RXX1
         SJMP   RDX1
RXX1:    CLR    RI
         MOV    A,  SBUF
         MOV    R4, A
         MOV    @R1,  A
         INC    R1
WAT1:    JBC    RI, LOOP3
         SJMP   WAT1
LOOP3:   CLR    RI
         MOV    A,  SBUF
         MOV    @R1, A
         INC    R1
         DJNZ   R4,  WAT1
         LJMP   MAIN
         END