前一讲所叙述的十种接口功能实质上都是逻辑电路。这些逻辑电路的特点是:在任一时刻的输出不仅仅与当时的输入有关,而且与这个电路的历史情况有关。因此,它们都是一些时序逻辑电路。我们知道,描绘时序逻辑电路的最好方法就是状态图。下面我们将用状态图`来详细解释这十种功能的特点。在状态图方法中,用一个圆圈来表示一个状态。圆圈里面的四个大写英文字母为该状态的名称。例如图2—1左圆圈代表听者空闲态 The ten interfaces described in the previous lecture are essentially logic circuits. The logic of these circuits is characterized by: The output at any one time is not only related to the input at that time, but also to the history of the circuit. Therefore, they are some timing logic. We know that the best way to describe sequential logic is the state diagram. Below we will use the state diagram `to explain in detail the characteristics of these ten features. In the statechart method, a circle is used to indicate a state. The four capital letters in the circle are the names of the states. For example, the left circle in Figure 2-1 represents the listener idle state