回车输出带码：

    mov ah,02h
    mov dl,0dh
    int 21h
    mov ah,02h
    mov dl,0ah
    int 21h

例子：先从键盘输入单字符，然后回车输出结果

DATAS SEGMENT
    ;此处输入数据段代码  
DATAS ENDS

STACKS SEGMENT
    ;此处输入堆栈段代码
STACKS ENDS

CODES SEGMENT
    ASSUME CS:CODES,DS:DATAS,SS:STACKS
START:
    MOV AX,DATAS
    MOV DS,AX
    
    mov ah,01h
    int 21h
    mov cl,al
    
    mov ah,02h
    mov dl,0dh
    int 21h
    mov ah,02h
    mov dl,0ah
    int 21h
    
    mov dl,cl
    
    mov ah,02h
    int 21h
        
    MOV AH,4CH
    INT 21H
CODES ENDS
    END START