8086 program to check whether a string is palindrome or not

Problem: Write an 8086 program to check whether a given string is palindrome or not.

Examples:

Input String: "abba"
Output: String is palindrome

Input String: "abbca"
Output: String is not palindrome

Explanation:

Create a string
Traverse to the end of the string
Get the address of the end of the string, DI
Load the starting address of the string, SI
Compare the value stored at the address
Increment the pointer, SI
Decrements the pointer, DI
Compare again the value stored at si and di
Repeat the steps until SI<=DI
If all the characters match print string is palindrome else print not palindrome

Program:

.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 plaindrome; 
    ;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 

Output:

String is palindrome

Note:
The program cannot be run on an online editor, please use MASM to run the program and use dos box to run MASM, you might use any 8086 emulator to run the program.

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