使用vhdl语言设计自动售邮票机。用两个发光二极管分别模拟售出面值为6角和8角的邮票，购买者可以通过开关选择一种面值的邮票，灯亮时表示邮票售出。用开关分别模拟1角、5角和1元硬币投入，用发光二极管分别代表找回剩余的硬币。 -Using vhdl language design vending stamp machine. Sold two light-emitting diodes were simulated nominal value of 60 cents and 80 cents s