Debugged flashing program

First, let's make the first light flash:

start: SETB P0.0; (1) turns off the light
       LCALL DELAY; (2) is a delay, calling the delay subroutine instruction
       CLR P0.0; (3) turns on the light
       LCALL DELAY; (4) is exactly the same as the second one, also calling the delay subroutine instruction

       LJMP start; (5) Jump back to execute the first instruction
DELAY: MOV R7, #250; (6) Let R7 be a counter and load a constant
D1: MOV R6, #250; (7) Let R6 be a counter and load a constant
D2: DJNZ R6, D2; (8) Let R6 decrement by 1 and determine whether R6 is 0. If R6 is 0, execute the instruction below. If R6 is not 0, jump to D2 and continue to decrement R6 by 1.
 DJNZ R7, D1; (9) Let R7 decrement by 1 and determine whether R7 is 0. If R7 is 0, execute the instruction below. If R7 is not 0, jump to D1 to make R6 complete a new round of counting.
 RET; (10) Return instruction.
 END; (11) End of program

Then there are the flashing programs:

;------------------Main program------------------
START: CLR P0.0;P0.0 outputs a low level to light up LED 1
       ACALL DELAY;Call the delay subroutine
       SETB P0.0;P0.0 outputs a high level to turn off LED1
       CLR P0.1;P0.1 outputs a low level to light up LED2
       ACALL DELAY;Call the delay subroutine
       SETB P0.1;P0.1 outputs a high level to turn off LED2
       CLR P0.2;P0.2 outputs a low level to light up LED3
       ACALL DELAY;Call the delay subroutine
       SETB P0.2;P0.2 outputs a high level to turn off LED3
       CLR P0.3;P0.3 outputs a low level to light up LED4
       ACALL DELAY;Call the delay subroutine
       SETB P0.3;P0.3 outputs a high level to turn off LED4
       CLR P0.4;P0.4 outputs a low level to light up LED5
       ACALL DELAY;Call the delay subroutine
       SETB P0.4;P0.4 outputs a high level to turn off LED5
       CLR P0.5;P0.5 outputs a low level to turn on LED6
       ACALL DELAY;Call the delay subroutine
       SETB P0.5;P0.5 outputs a high level to turn off LED6
       CLR P0.6;P0.6 outputs a low level to turn on LED7
       ACALL DELAY;Call the delay subroutine
       SETB P0.6;P0.6 outputs a high level to turn off LED7
       CLR P0.7;P0.7 outputs a low level to turn on LED8
       ACALL DELAY;Call the delay subroutine
       SETB P0.7;P0.7 outputs a high level to turn off LED8
       ACALL DELAY;Call the delay subroutine
       AJMP START;After the eight lights are on, return to the beginning and loop again
       ;------Delay subroutine-------
DELAY: MOV R0,#255;R0 is loaded with 255
D1: MOV R1,#255;Load 255 into R1
       DJNZ R1,$;Decrement R1 to zero and then execute the next instruction
       DJNZ R0,D1;Decrement R0 by 1. If it is zero, execute the next instruction. If it is not zero, jump to D1
       RET;Return from the subroutine
;============================================================================================================;
 END;End of program