这次设计的抢答器主要四部分组成，由优先编码器，寄存器和译码器组成的抢答电路，十进制计数器组成的倒计时电路，555定时器组成的秒脉冲发生器，十六进制计数器组成的计数器。-The design of the Responder mainly of four parts, by the priority encoder, register, and the composition of the answer in the decoder circuit, consisting of decimal c