This book addresses the experimental needs of students, researchers, and teachers of various disciplines in science, engineering, and technology on microcontrollers at the graduate and post-graduate level. One of the most widely produced and used microcontrollers in the world is the 8051. A basic knowledge of 8051 microcontroller is required to understand the experiments is given in the book. This book is organised into three parts. Part I deals with software experiments - addition, subtraction, multiplication, code conversion etc. All software programmes are written in assembly language. Part II describes hardware experiments. Some of the hardware experiments are designed with microcontroller kits and many are discussed with 89C51 microcontroller alone. Every experiment is written in such way that an experimenter need not require additional information to perform the experiment. In most of the experiments both assembly language and embedded C programmes are given. Part III deals with completed projects. These projects are related to the applications of a microcontroller either for measuring and/or controlling a parameter. The salient features and descriptions of sensors/transducers, signal conditioning elements and actuators are provided wherever necessary.