输入一个ascii，程序获取值，再输出

.model small
.code
mov ah,1
int 21h
mov ah,2
mov dl,al
int 21h
.exit 0
end

code segment
assume cs:code
start:
    mov ah,1
    int 21h
    mov ah,2
    mov dl,al
    int 21h
    mov ah,4ch
    int 21h
code ends
end start