Notes

.MODEL SMALL
.STACK 100H
.DATA

; The string to be printed
STRING DB 'abba', '$'
STRING1 DB 'String is palindrome', '$'
STRING2 DB 'String is not palindrome', '$'

.CODE
MAIN PROC FAR
MOV AX, @DATA
MOV DS, AX

; check if the string is;
;palindrome or not
CALL Palindrome

;interrupt to exit
MOV AH, 4CH
INT 21H
MAIN ENDP
Palindrome PROC

; load the starting address
; of the string
MOV SI,OFFSET STRING

; traverse to the end of;
;the string
LOOP1 :
MOV AX, [SI]
CMP AL, '$'
JE LABEL1
INC SI
JMP LOOP1

;load the starting address;
;of the string
LABEL1 :
MOV DI,OFFSET STRING
DEC SI

; check if the string is palindrome;
;or not
LOOP2 :
CMP SI, DI
JL OUTPUT1
MOV AX,[SI]
MOV BX, [DI]
CMP AL, BL
JNE OUTPUT2

DEC SI
INC DI
JMP LOOP2

OUTPUT1:
;load address of the string
LEA DX,STRING1

; output the string;
;loaded in dx
MOV AH, 09H
INT 21H
RET

OUTPUT2:
;load address of the string
LEA DX,STRING2

; output the string
; loaded in dx
MOV AH,09H
INT 21H
RET

Palindrome ENDP
END MAIN