Q. Create an input buffer ?

CODE SEGMENT

...

MOV AH, 0AH                       ; Move 04 to AH register

MOV DX, BUFF                   ; BUFF must be defined in data segment.

INT   21H

.....

CODE ENDS

DATA SEGMENT

  BUFF DB 50    ; max length of string,

    ; including CR, 50 characters

    DB?  ; Actual length of string not known at present 

    DB 50 DUP (0); buffer having 0 values

DATA ENDS.

Explanation

The above DATA segment creates an input buffer BUFF of maximum 50 characters. On input of data "JAIN" followed by enter data will be stored as below: