51 MCU serial communication test assembly program

(I just figured it out today): PC transmits commands and data to the MCU system through the serial port assistant: it starts with A5 and ends with 5A; the data in the middle has different lengths, and the data part is required to be displayed with LED lights; and it is required to be displayed in a loop;

//This is my x_Ed program code
//we use it as the pc communicated with the mcu
//At the same time,we want to see the result by LCD; 
     STFLAG BIT 00H //Received start code flag, 1 for received start code
     EDFLAG BIT 01H //Arrived end code flag, 1 for received end code
     TMFLAG BIT 02H //Timing time arrived flag, 1 for timing time arrived
  ORG 0000H
  SJMP Initialize//Main program entry (initialization program)
  ORG 000BH //Timer 0 entry
     LJMP TIMER0 //Timer 0 interrupt
  ORG 0023H //Entry address of serial port interrupt program
  LJMP Transfer //Jump to accept interrupt entry
////////////////////////////////////////////////////////////////////
     ORG 0050H
Initialize:
     MOV SP,#70H //Set stack
  MOV TMOD,#21H //T1 working mode 2 T0 working
  MOV TH1,#0FDH //Baud rate 9600
  MOV TL1,#0FDH //Baud rate 9600 automatic reload
  MOV TH0,#3CH //Timing 50ms
     MOV TL0,#0BH //Timing 50ms
  MOV SCON,#50H //Serial port working mode 1
     MOV R6,#00H //Timing times counter 20 one second
     MOV R5,#00H //Received data length counter
     MOV R4,#00H //Control output control register
     MOV R0,#30H //Data storage address
     MOV R1,#30H //Control output data cache
     CLR STFLAG //Clear start flag
     CLR EDFLAG //Clear end flag
     CLR TMFLAG //Clear clock flag
     SETB PS //Increase the priority of serial port interrupt
     SETB TR1 //Turn on timer 1;
     SETB ES //Turn on serial port interrupt enable bit
     SETB ET0 //Timer 0 interrupt enable bit
     SETB EA //Turn on global interrupt enable bit
//////////////////Wait for receiving command ////////////////////////
Main: JB STFLAG,NODE3 //Start bit has been received
        SJMP Main //Not started, continue waiting
NODE3: JB EDFLAG,NODE4 //End bit has been received
        SJMP Main //Not ended, continue waiting
NODE4: SETB TR0 //Turn on timer 0;
NODE5: JB TMFLAG,OUTPUT
  SJMP NODE5         
 ////////////////////Wait for host computer to transmit data and record it ////////
Transfer: CLR ES
          MOV A,SBUF
    CJNE A,#0A5H,NODE0 //Start bit detected
    SETB STFLAG
    SJMP JIEDIAN
NODE0: CJNE A,#05AH,NODE1 //Detect the end bit
          SETB EDFLAG
    MOV DPH,R5
    MOV R4,DPH
    clr ES //Open the serial port interrupt enable bit
    SJMP ret00
NODE1: MOV @R0,A //Neither the start code nor the end code, it is data
          INC R0
          INC R5
    MOV SBUF,#055H  
JIEDIAN: CLR TI
    CLR RI
          SETB ES
ret00: RETI
TIMER0: CLR TR0
        MOV TH0,#3CH
        MOV TL0,#0B0H
        INC R6
        CJNE R6,#20,RTN
        SETB TMFLAG
        MOV R6,#00H
RTN: SETB TR0
     RETI

OUTPUT: CLR TR0
        clr TMFLAG
        MOV A,@R1
        MOV P1,A
        INC R1
        DJNZ R4,NODE4
        MOV R1,#30H
  CLR TMFLAG
  MOV DPH,R5
  MOV R4,DPH
  SJMP NODE4
  RETI
END