RS232接口接收数据时，可以采用查询和中断两种方式，其中采用中断方式的特点是（)。
- A.硬件电路简单，易于设计
- B.不长期占用CPU资源，系统开销小
- C.设计复杂，降低了系统的实时性
- D.软件设计简单，可移植性好
正确答案及解析
正确答案
解析
外设数据传输，程序查询方式是CPU一直等待数据传输完，中断方式是传输完成后发送中断让CPU来处理，二者之间显著的区别就在于是否长期占用CPU资源，中断方式CPU可以并行处理其他进程，只要当传输完成后才需要响应中断处理。这里题目特地指出查询和中断两种方式，应该从二者区别的角度入手。
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