1 ; multi-segment executable file template. 2 3 data segment 4 5 ends 6 7 stack segment 8 dw 128 dup(0) 9 ends 10 11 code segment 12 start: 13 ; set segment registers: 14 mov ax, data 15 mov ds, ax 16 mov es, ax 17 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 21H 22 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？;below 24 CMP AL, 9 ;输入字符>'9'吗？;above 25 JA STOP 26 CBW ;AL扩展到AH 27 MOV CX, AX ;响铃次数N 28 JCXZ STOP 29 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 21H 33 LOOP BELL 34 STOP: RET 35 36 ; wait for any key.... 37 mov ah, 1 38 int 21h 39 40 mov ax, 4c00h ; exit to operating system. 41 int 21h 42 ends 43 44 end start ; set entry point and stop the assembler.