程序主要是用硬件描述语言（VHDL）实现： 4*4键盘扫描，简洁明了，通俗易懂，比较适合VHDL初学者-procedure was used in hardware descr iption language (VHDL) to achieve : 4 * 4 keyboard scan, concise, easily understood and more suitable for beginners VHDL