计算机输入设备输入的信息一般是由ASCII码或BCD码表示的数据或字符，CPU一般均用二进制数进行计算或用其他信息进行处理，处理的结果又必须依照外设的要求变为ASCII码、BCD码或七段显示码等。因此，在应用软件中，各类数制的转换和代码的转换是必不可少的-Computer input device input information is normally provided by ASCII code or BCD code that data or characters, CPU are generally calculated using binary number or other information processing, the results must be in accordance with the requirements of peripherals into ASCII code, BCD code or code, such as Seven-Segment display. Therefore, in the application software, all kinds of number system conversion and the conversion code is essential