[汇编] 从键盘输入一个一位数字，然后响铃n声

 ; multi-segment executable file template.

 data segment

 ends

 stack segment
     dw     dup()
 ends

 code segment
 start:
 ; set segment registers:
     mov ax, data
     mov ds, ax
     mov es, ax

     ; add your code here
     BEGIN:
     MOV    AH,             ;从键盘输入一个字符的DOS调用AL存放输入的字符
     INT        21H
     SUB        AL, ''     ;输入的是字符需要转化为数字
     JB        STOP                    ;输入字符<''吗？;below
     CMP    AL,                          ;输入字符>''吗？;above
     JA        STOP
     CBW                             ;AL扩展到AH
     MOV    CX, AX                        ;响铃次数N
     JCXZ    STOP
         BELL:
         MOV    DL, 07H                    ;准备响铃
         MOV    AH,                     ;显示一个字符的DOS调用，实际为响铃
         INT        21H
         LOOP    BELL
     STOP:        RET

     ; wait for any key....
     mov ah,
     int 21h

     mov ax, 4c00h ; exit to operating system.
     int 21h
 ends

 end start ; set entry point and stop the assembler.