XL2000 8051 development board experiment 4 seven segment display multiplexed

org 0000h ; start
ajmp loop ; jump to 0030h
org 0080h ;
LOOP:
MOV P1,#0 ; set 1 to p1 port
CALL DELAY ;delay
MOV P1,#1 ; set 1 to p1 port
CALL DELAY ;delay
MOV P1,#2 ;set 2 to p1 port
CALL DELAY ;delay
MOV P1,#3
CALL DELAY
MOV P1,#4
CALL DELAY
MOV P1,#5
CALL DELAY
MOV P1,#6
CALL DELAY
MOV P1,#7
CALL DELAY
MOV P1,#8
CALL DELAY
MOV P1,#9
CALL DELAY
JMP LOOP ;restart

DELAY: MOV R5,#50 ;delay subprogram
D1: MOV R6,#40
D2:MOV R7,#248
DJNZ R7,$
DJNZ R6,D2
DJNZ R5,D1
RET
END