Digital Systems

Chapter 19

Hazards and Pulse Mode Sequential Circuits

OBJECTIVE

We will learn in this chapter the hazards that are present in a logic circuit when two inputs change due to a single logic variable. We will also learn about pulse mode sequential circuits. Hazard means a source of trouble or risk.

We learnt in Chapter 18 the following important points:

1. A general asynchronous sequential circuit is a circuit in which there are no control(s) for the instance(s) at which the output(s) change like a control by a clocked instance in synchronous sequential circuit.
2. The circuit has a section consisting of the (i) combinational circuits at the input and output stages and (ii) latches (without clock inputs) or an equivalent delay devices, which have ...