Hi, My assignment is to write a program which uses a momentary switch to latch an LED on/off. It seems to be intermittant as it's difficult to describe what it is doing...sometimes it works as expected and other times the led just blinks without latching. The switch is connected to pin0 of port A and the LED is connected to pin0 of port E.Any help would be appreciated.Thank you in advance.

.ORG 2000H
MOV A,#9FH ;SET UP
MOV DPTR,#0F803H ; PORT A
MOVX @DPTR,A ; AS AN INPUT
MOV A,#89H ;SET UP
MOV DPTR,#0F903H ; PORT E
MOVX @DPTR,A ; AS AN OUTPUT
MOV 40H,#00 ;CLEAR FLAG-IS LED ON/OFF
MOV A,#0FFH
MOV DPTR,#0F901H ;POINT TO PORT E
MOVX @DPTR,A ;TURN OFF LEDS TO PORT E
READ:MOV DPTR,#0F800H ;POINT TO PORT A
MOVX A,@DPTR
JNZ DELAY ;
MOV A,40H ;MONITOR FLAG
JNZ CLEAR ;
INC 40H ;SET FLAG
MOV DPTR,#0F901H ;POINT TO PORT E
MOV A,#0FEH ;
MOVX @DPTR,A ;TURN ON LED
SJMP READ
CLEAR:DEC 40H ;CLEAR FLAG
MOV DPTR,#0F901H ;POINT TO PORT E
MOV A,#0FFH ;
MOVX @DPTR,A ;TURN OFF LED
SJMP READ