Digital Systems: Principles and Design

353Sequential Circuits Analysis, State Minimization, State Assignment and Circuit Implementation

15.1 GENERAL SEQUENTIAL CIRCUIT WITH A MEMORY SECTION

AND COMBINATIONAL CIRCUITS AT THE INPUT AND

OUTPUT STAGES

A general sequential circuit network has memory section and combination circuits at the

memory inputs and outputs. Assume the followings structure of a general sequential circuit.

1. The circuit memory section consists of the m of flip flops. These have a set Q with

the m present state outputs Q0, Q1... and Qm  1.

2. There is a set

X of i inputs X0, X1, ... Xi. These are applied to a combinational cir-

cuit, the j outputs of which are the inputs ...