80x86 program, need help for modifying program

 MOV BL,70 ; [70] is the address where the text will
    ; be stored. The procedure uses this.

CALL 10 ; The procedure at [10] reads in text and
    ; places it starting from the address
    ; in BL.

   ; BL should still contain [70] here.

CALL 40 ; This procedure does nothing until you
    ; write it. It should display the text.


   ; DON'T USE END HERE BY MISTAKE.
 ; --------------------------------------------------------------
 ; A PROCEDURE TO READ IN THE TEXT
 ORG 10 ; Code starts from address [10]

PUSH AL ; Save AL onto the stack
 PUSH BL ; Save BL onto the stack
 PUSHF  ; Save the CPU flags onto the stack

Rep:
 IN 00 ; Input from port 00 (keyboard)
 CMP AL,0D ; Was key press the Enter key?
 JZ Stop ; If yes then jump to Stop
 MOV [BL],AL ; Copy keypress to RAM at position [BL]
 INC BL ; BL points to the next location.
 JMP Rep ; Jump back to get the next character

Stop:
 MOV AL,0 ; This is the NULL end marker
 MOV [BL],AL ; Copy NULL character to this position.

POPF  ; Restore flags from the stack
 POP BL ; Restore BL from the stack
 POP AL ; Restore AL from the stack

RET  ; Return from the procedure.
 ; --------------------------------------------------------------
 ; A PROCEDURE TO DISPLAY TEXT ON THE SIMULATED SCREEN
 ORG 40 ; Code starts from address [10]
    ; **** YOU MUST FILL THIS GAP ****
 RET  ; At present this procedure does
    ; nothing other than return.

; --------------------------------------------------------------
 END  ; It is correct to use END at the end.
 ; --------------------------------------------------------------