8051单片机的P1口作为8个按键的输入端，构成独立式键盘。四个LED显示器通过四个串/并移位寄存器74LS164接口至8051的串行口，该串行口应工作在方式0发送状态下，RXD端送出要显示的段码数据，TXD则作为发送时钟来对显示数据进行移位操作。-8051 P1 port as a the eight key input end, constitute a stand-alone keyboard. Four LED displays through four serial/parallel shift register 74LS164 interface to the 8051 serial port, the serial port should work in the way 0 send state, RXD client sends a segment code data to be displayed, TXD as the transmit clock to display data shift operation.