4.asm

4.asm…… 响铃程序

stack   segment stack
        dw 512 dup(?)
stack   ends
data    segment
string  db 'Enter a number:',0ah,0dh,'$'
data    ends
code    segment 'code'
        assume cs:code,ds:data,ss:stack
start:  mov ax,data
        mov ds,ax
        mov ah,09h
        mov dx,offset string
        int 21h
        mov ah,1
        int 21h
        and al,0fh
        mov cl,al
        mov ch,0
bell:   mov ah,02h
        mov dl,07h
        int 21h
        loop bell
        mov ax,4c00h
        int 21h
code    ends
        end start