GETSTR MACRO STR
MOV AH,0AH
LEA DX,STR
INT 21H
ENDM

PRINTSTR MACRO STR
MOV AH,09H
LEA DX,STR
INT 21H
ENDM


DATA SEGMENT
    STR1 DB 80,80 DUP('$')
    STR2 DB 80,80 DUP('$')
    MSG1 DB 10,13,'ENTER THE STRING :$'
    MSG2 DB 10,13,'THE REVERSE STRING IS :$'
    STORE DB 2 DUP('$')
DATA ENDS


CODE SEGMENT

        ASSUME CS:CODE,DS:DATA
        START:

                 MOV AX,DATA
                 MOV DS,AX

                 PRINTSTR MSG1
                 GETSTR STR1
                 PRINTSTR MSG2
        
                 LEA SI,STR1+2
                 LEA DI,STR2+2
        
                 MOV CL,STR1+1    ;FOR STORING THE LENGTH OF THE STRING
                 MOV CH,00H
                 MOV BL,CL
                 MOV BH,00H
        
         LAB1:
                 INC SI           ;FOR GOING TO THE END OF THE STRING
                 LOOP LAB1

                 MOV CX,BX

         LAB2:
                 MOV AL,DS:BYTE PTR[SI] ;FOR COPYING CONTENTS OF STR1 TO AL
                 MOV DS:BYTE PTR[DI],AL ;FOR COPYING CONTENTS OF AL TO STR2
                 INC DI
                 DEC SI
                 LOOP LAB2
           
         PRINTSTR STR2+2       
         MOV AH,DS:BYTE PTR[SI]
         MOV STORE,AH
         PRINTSTR STORE

           
         MOV AX,4C00H
         INT 21H

CODE ENDS
        END START

OUTPUT
***********

D:\tasm\tasm1>m1

ENTER THE STRING :abc
cba REVERSE STRING IS