本库利用51的timer2，9600bps适用于有片内外部存储器的51芯片占用32byte缓存，重写putchar,getchar函数，循环队列，后台操作。-for the use of timer2 51, 9600 applied to the external memory unit within the occupied 32byte 51 chip cache, rewritten putchar, getchar function, circulating cohort, background operation.