说明：  学习pcb相关软件时我个人认为最重要的是在布线，这是一本专门关于protel99的pcb布线的书（原理图部分也公布在此网站上了）
(Pcb learning software, I personally think that the most important thing is in the wiring, which is a specialized on the pcb wiring protel99 book (also published some schematics on this site a))