This document provides an overview of microprocessors and microcontrollers. It discusses the evolution from transistors to integrated circuits and the development of microprocessors and microcontrollers. A microprocessor is the central processing unit of a computer system, while a microcontroller incorporates a microprocessor along with memory and input/output ports on a single chip. The document describes the components of microprocessor-based systems including the CPU, memory, I/O circuitry and buses. It also discusses different types of memory and I/O ports. Microcontrollers are commonly used in embedded systems to control machines.