公 共 电 话 通 话 计 费 系 统　　在本课程中所选择的课题是用Verilog HDL实现的公共电话。该公共电话所实现的功能有打电话、修改密码。

公共电话共包括以下几个状态：挂机、待机、身份确认、修改密码、通话等五个状态。-The pay phone converses to charge system

In this course the topic chosen is use Verilog HDL carry out of pay phone.The function carried out by that pay phone has already made a phone call, modified password.

The pay phone totally includes a few following appearances:Hang machine, need a machine, identity to confirm, modification password, converse etc. five appearances.