To check whether the string is palindrome or not

DATA SEGMENT
            MSG1 DB 10,13,'ENTER ANY STRING :- $'
            MSG2 DB 10,13,'ENTERED STRING IS :- $'
            MSG3 DB 10,13,'LENGTH OF STRING IS :- $'
            MSG4 DB 10,13,'NO, GIVEN STRING IS NOT A PALINDROME $' 
            MSG5 DB 10,13,'THE GIVEN STRING IS A PALINDROME $'
            MSG6 DB 10,13,'REVERSE OF ENTERED STRING IS :- $' 
            P1 LABEL BYTE
            M1 DB 0FFH
            L1 DB ?
            P11 DB 0FFH DUP ('$')
                P22 DB 0FFH DUP ('$')
        DATA ENDS 
        DISPLAY MACRO MSG
            MOV AH,9
            LEA DX,MSG
            INT 21H
        ENDM   
        CODE SEGMENT
            ASSUME CS:CODE,DS:DATA
        START:
                MOV AX,DATA
                MOV DS,AX                

    DISPLAY MSG1

    LEA DX,P1
    MOV AH,0AH    
    INT 21H

    DISPLAY MSG2

    DISPLAY P11

    DISPLAY MSG3

    MOV DL,L1
    ADD DL,30H
    MOV AH,2
    INT 21H

    DISPLAY MSG6

    LEA SI,P11
    LEA DI,P22

    MOV DL,L1
    DEC DL
    MOV DH,0
    ADD SI,DX
    MOV CL,L1
    MOV CH,0

REVERSE:
        MOV AL,[SI]
        MOV [DI],AL
        INC DI
        DEC SI
        LOOP REVERSE

    DISPLAY P22

    LEA SI,P11
    LEA DI,P22   

    MOV CL,L1
    MOV CH,0

CHECK:
        MOV AL,[SI]
        CMP [DI],AL
        JNE NOTPALIN
        INC DI
        INC SI
        LOOP CHECK


    DISPLAY MSG5
    JMP EXIT
NOTPALIN:
        DISPLAY MSG4

EXIT:   MOV AH,4CH
        INT 21H
CODE ENDS
END START