自己编写的8254计数器／计时器，实现了所有的６种模式，和大家一起分享。-I have written 8254 counter/timer, realize all the six kinds of patterns, and the U.S. share.

基于8254 ip 核的vhdl的实现以及对于quart 2的实现及应用-Based on the 8254 IP core of the realization of VHDL and for the implementation and application quart 2