Chapter 2: Combinational and Sequential Logic

Introduction

Combinational and sequential logic circuits form the foundation of digital circuit design. Combinational logic circuits generate outputs based solely on the current inputs, while sequential logic circuits incorporate memory elements, allowing them to store state information and react to both current and past inputs.

This chapter provides an in-depth understanding of:

• The principles of combinational logic, including building blocks such as adders, multiplexers, decoders, encoders, and arithmetic logic units (ALUs).
• The fundamentals of sequential logic, covering flip-flops, shift registers, counters, and memory elements.
• The key differences between combinational and sequential circuits and their applications in digital systems.

Topics Covered

• Combinational Logic Circuits
  • Basic Logic Gates
  • Adders and Subtractors
  • Multiplexers (MUX) and Demultiplexers (DEMUX)
  • Decoders and Encoders
  • Comparators
  • Arithmetic Logic Units (ALUs)
• Sequential Logic Circuits
  • Flip-Flops (SR, D, JK, T)
  • Shift Registers
  • Asynchronous vs. Synchronous Counters
  • Memory Elements and Storage Devices

Learning Objectives

• Understand the distinction between combinational and sequential circuits.
• Design and analyze combinational circuits, including adders, multiplexers, and ALUs.
• Implement sequential circuits using flip-flops, counters, and shift registers.
• Apply these principles to **practical digital system designs**.

This chapter serves as a bridge to **Finite State Machines (FSMs) and Register Transfer Level (RTL) Design**, covered in later chapters.