国家晶片系统设计中心的VHDL设计资料，包括VHDL语法，同步约束，频率设计，系统模拟和源码实验等高难技术的讲解-National Chip Implementation Center of the VHDL design, including VHDL syntax, synchronization constraints, frequency design, system simulation and difficult to source high technology to explain the experimental