中文说明：
用vhdl的4x4的数据选择器，在maxplusII下编译、仿真通过。是构成大型数字电路的重要部件。适合vhdl初学者分析学习。
English Description：
The 4x4 data selector of VHDL is compiled and simulated under maxplus II. It is an important component of large-scale digital circuit. Suitable for VHDL beginners to analyze and learn