物理层

物理层定义和功能
https://blog.csdn.net/qq_46331050/article/details/120206230
怎么测电脑电源电压
http://www.dn119.cn/itzixun/7835.html https://b23.tv/GT5qjry
双绞线
https://baijiahao.baidu.com/s?id=1757066694861125347&wfr=spider&for=pc&searchword=%E5%B9%B3%E5%B8%B8%E7%94%A8%E7%9A%84%E5%8F%8C%E7%BB%9E%E7%BA%BF%E6%98%AF%E4%BB%80%E4%B9%88%E6%A0%B7%E7%9A%84

计算机的串并行接口

https://blog.csdn.net/qq_41322802/article/details/106368455