dseg segment  
  mess1 db "select 1--Set password",0ah,0dh 
        db "select 2--display password",0ah,0dh 
        db "select 3--check passwork",0ah,0dh 
        db "select other keys--quit",0ah,0dh,"$" 
  mess2 db "Input your selection:",0ah,0dh,"$" 
  mess3 db "999999",0ah,0dh,"$" 
  mess4 db "your password is error,please check!",0ah,0dh,"$" 
  mess5 db "your password is right,please countiune",0ah,0dh,"$" 
  mess6 db "please input your 6s password:","$" 
  xing  db "*","$" 
  endbz db 0ah,0dh,"$" 
dseg ends 
sseg segment stack 
  db 80h dup(0) 
sseg ends 
cseg segment 
  assume ds:dseg,ss:sseg,cs:cseg 
  ;************進行菜單的設計******************
start:   mov ax,   dseg 
        mov ds,  ax 
        mov dx, offset mess1 
        mov ah,09h 
        int 21h   
        mov dx, offset mess2 
        mov ah,09h 
        int 21h   
        mov ah,08h 
        int 21h 
        and al, 0fh 
        cmp  al, 1 
        jz setpass   ;輸入1則進行密碼設定              
        cmp al, 2 
        jz display   ;輸入2顯示密碼
        cmp al, 3 
        jz  check    ;輸入3修改密碼
        jmp end0 
 setpass:     ;進行密碼設定
        mov dx, offset mess6 
        mov ah,09h 
        int 21h 
        mov cl,6 
        mov dx, offset mess3 
        mov bx, dx 
loop0:   mov ah,08h 
        int 21h 
        mov [bx],  al 
        mov dx ,offset xing 
        mov ah,09h 
        int 21h 
        inc bx 
        dec cl 
        jnz loop0 
        mov dx, offset endbz 
        mov ah,09h 
        int 21h 
        jmp start 
check:  mov dx, offset mess6 
        mov ah, 09h 
        int 21h 
        mov cl,6 
        mov dx, offset mess3 
        mov bx, dx       
loop1:   mov ah,01h 
        int 21h 
        cmp [bx],  al 
        jnz error 
        inc bx 
        dec cl 
        jnz loop1 
        mov dx, offset endbz 
        mov ah, 09h 
        int 21h 
        mov dx, offset mess5 
        mov ah, 09h 
        int 21h 
        jmp start 
   error: mov dx, offset endbz 
        mov ah, 09h 
        int 21h 
        mov dx, offset mess4 
        mov ah, 09h 
        int 21h               
        jmp start 
display: mov dx, offset mess3  ;密碼的顯示
        mov ah,09h 
        int 21h 
        jmp start 
end0: mov ah,4ch   ;退出
        int 21h 
cseg    ends           
        end