1.引言线性开关电路已相当广泛地应用于许多领域,其中能产生伪随机序列的移位寄存器更是为大家所熟悉,并且关于这种网络的理论已十分完善。计数式网络也常为人们所采用。本文讨论的是一种特殊的计数式网络—循环计数链。见图一,其中每个→R(?)→都是计数单元,即有输入(1)时,本身状态要改变;无输入(0)时。状态保持不变。若用延迟单元来表示,图一就可画成与其等价的图二那种形式 1. INTRODUCTION Linear switching circuits have found widespread use in many fields, including shift registers that produce pseudo-random sequences, which are well known to all and whose theory of such networks is well established. Counting networks are often used by people. This article discusses a special counting network - loop count chain. See Figure 1, where each → R (?) → is a counting unit, that is, when the input (1), its own state to change; no input (0). The state remains unchanged. If the delay unit to represent, Figure 1 can be drawn as the equivalent of Figure II that form