1 ; multi-segment executable file template. 2  3 data segment 4  5 ends 6  7 stack segment 8     dw   128  dup(0) 9 ends10 11 code segment12 start:13 ; set segment registers:14     mov ax, data15     mov ds, ax16     mov es, ax17 18     ; add your code here 19     BEGIN:        20     MOV    AH, 1            ;从键盘输入一个字符的DOS调用AL存放输入的字符21     INT        21H22     SUB        AL, '0'     ;输入的是字符需要转化为数字23     JB        STOP                    ;输入字符<'0'吗？;below24     CMP    AL, 9                         ;输入字符>'9'吗？;above25     JA        STOP26     CBW                             ;AL扩展到AH27     MOV    CX, AX                        ;响铃次数N28     JCXZ    STOP29         BELL:        30         MOV    DL, 07H                    ;准备响铃31         MOV    AH, 2                    ;显示一个字符的DOS调用，实际为响铃32         INT        21H33         LOOP    BELL34     STOP:        RET35 36     ; wait for any key....    37     mov ah, 138     int 21h39     40     mov ax, 4c00h ; exit to operating system.41     int 21h    42 ends43 44 end start ; set entry point and stop the assembler.