普通的缓冲器 这种设计是一个普通的缓冲器，可以做一个直接的缓冲器，也可以做一个双向的转移缓冲器，还可以做一个递增的计数器和递减计数器-Universal Register This design is a universal register which can be used as a straightforward storage register, a bi-directional shift register, an up counter and a down counter.