;从键盘输入一个小写字母,找出它的前导字符和后续字符,在按顺
;序显示这三个字符.
code segment
assume cs:code
start:  mov ah,1
        int 21h
        cmp al,'a'
        jb  stop
        cmp al,'z'
        ja  stop
        dec al
        mov dl,al
        mov cx,3
p1:     mov ah,2
        int 21h
        inc dl
        loop p1
stop:   mov ah,4ch
        int 21h
code    ends
        end start