AT89C51 MCU timer terminal mode and query settings

bb: mov p1,#3fh ;at the main program entry
        mov tmod,#05h ;05h=0000 0101B Set T1 timing T0 counting mode, 0 timing, 1 counting
                                      ; 00 is 13-bit binary counting mode 0, the upper 4 bits control T1
                                      ; 01 is 16-bit binary counting mode 1, the lower 4 bits control T0
        mov dptr,#0300h ;store the table entry address
        mov r2,#00h                 
        setb et0 ;same effect as setb 0afh 
        setb ea ;same as setb 0abh
        setb et1 ;same as setb 0a9h

        setb tr0
        setb tr1
       
        mov th0,#0ffh ;The upper 8 bits of the initial count value of counter 0
        mov tl0,#0fdh ;The lower 8 bits of the initial count value of counter 0 (the initial count value for the first time)
        sjmp $ ;When the program is executed, it will wait for the statement in place. When there is no interrupt request,
                                      ;it will count in place at this position and jump to the interrupt entry to execute the interrupt when there is a request
xx: inc r2
xx11: mov th0,#0ffh ;The upper 8 bits of the initial count value of counter 0
           mov tl0,#0fdh ;The lower 8 bits of the initial count value of counter 0 (the initial count value for the second time and after)  
           mov a,r2
           movc a,@a+dptr
           cpl p2.5
           mov p1,a           
           reti

xxx: mov th1,#00h ; the upper 8 bits of the initial count value of counter 1
            mov tl1,#00h ; the lower 8 bits of the initial count value of counter 1
            cpl p2.0
            reti

           org 0300h ; seven-segment display table entry
           db 3fh, 06h, 5bh, 4fh, 66h, 6dh, 7dh, 07h, 7fh, 6fh
          end
2. Timer/Counter Query Mode
          org 0000h
          ljmp bb ; jump to main program entry bb

bb: mov tmod,#15h ; At the main program entry
                                        ; Set T1 timing mode to work in counting mode 0, set T0 counting mode  
                                        to work in counting mode 1

        mov dptr,#0300h ;store the table entry address        
                             
        clr et0 ;turn off timer/counter 0 interrupt
        setb ea ;same as setb 0abh, turn on the general interrupt switch
        setb et1 ;same as setb 0a9h, turn on timer/counter 1 interrupt   
        setb tr0
        setb tr1       
        mov th0,#0ffh ;high 8 bits of the initial count value of counter 0
        mov tl0,#0ffh ;low 8 bits of the initial count value of counter 0 (initial value for the first start of counting)
  CX: JBC TF0, xx ;query the overflow flag of timer/counter 0, if there is overflow, jump to xx to execute
         JBC TF1, xxx ;query the overflow flag of timer/counter 1, if there is overflow, jump to xxx to execute
         sjmp CX ;no overflow, jump to CX to continue querying
   ;overflow occurs when THi and TLi count fully and exceed FFFFH, TFi is automatically set to 1, interrupts and queries are
   responded to based on whether this flag is 1.                         
xx: mov th0,#0ffh ;high 8 bits of counter 0 count initial value
           mov tl0,#0ffh ;low 8 bits of counter 0 count initial value (start counting initial value after the second time)  
           cjne r2,#10d,xx11      
           mov r2,#00h
xx11: mov a,r2
           movc a,@a+dptr ;look up the table and use seven-segment code to display the count number
           cpl p2.5 ;and make the LED on P2.5 have a flashing effect
           mov p1,a ;display the digital effect and output from P1 port
           inc r2 ;add 1 to count  
           ret

xxx: mov th1,#00h ; the high 8 bits of the initial count value of counter 1
           mov tl1,#00h ; the low 8 bits of the initial count value of counter 1
           cpl p2.0 ; t0 timing mode, when the timing is reached, P2.0 is inverted, and the LED achieves a flashing effect
           ret

           org 0300h ; seven segment display table entry
    db 3fh,06h,5bh,4fh,66h,6dh,7dh,07h,7fh,6fh
          end