key identification in assembly language 8086

.model small
.stack 64h
.data
st1 db 'home $'
st2 db 'other $'
CTR DB 00H
.code
MAIN PROC FAR
MOV AX,@DATA
MOV DS,AX
A20:
MOV AH,10H
INT 16H
CMP Ah,47h
JE B10
MOV AH,09H
LEA DX,ST2
INT 21H

CMP CTR,09H
JNE A50
jmp a20
 B10:
 MOV AH,09H
 LEA DX,ST1
 INT 21H
 JMP A20
a50:
 MOV AH,4CH
 INT 21H
 MAIN ENDP
 END MAIN