用汇编实现人机对话？

DATA SEGMENT
MESG1 DB 0DH,0AH,'What is your name?$'
MESG2 DB 'Oh,I know,you are $'
BUF DB 30
DB ?
DB 30 DUP(?)
DATA ENDS

CODE SEGMENT
ASSUME CS:CODE,DS:DATA
BEG: MOV AX,DATA
MOV DS,AX
AGAIN: MOV AH,9 ;显示字符串MESG1
MOV DX,OFFSET MESG1
INT 21H

MOV AH,0AH ;有回显等待输入
MOV DX,OFFSET BUF
INT 21H

MOV BL,BUF+1
MOV BH,0
MOV SI,OFFSET BUF+2
MOV BYTE PTR[BX+SI],'$' ;BUF串末加'$'

MOV AH,2
MOV DL,0AH ;输出换行
INT 21H

MOV AH,9
MOV DX,OFFSET MESG2 ;输出Oh,I know...
INT 21H

MOV AH,9
MOV DX,OFFSET BUF+2 ;输出输入的人名
INT 21H

MOV AH,1
INT 21H
MOV AH,4CH
INT 21H
CODE ENDS
END BEG