利用VHDL编写的简易自动售货机。本次设计的自动售货机只销售cola与pepsi两种饮料，售价均为1.5元。顾客可以由两个不同投币孔分别投入5角硬币或1元硬币。一次交易只能购买一瓶，且自动找零。只要按下取消键就会马上无条件退币。-Using a simple vending machine in VHDL. The design of the vending machines selling cola and pepsi only two drinks, both at 1.5 yuan. Customers can put 50 cents or one dollar coins coins from two different coin holes. A transaction can only buy a bottle and change automatically. Just press the Cancel button will immediately unconditional coin.