For every PC there are at least 20 embedded systems, and the number is increasing. 8051 is one of the most widely used microcontrollers in embedded system design, and its internal architecture, instruction set and interfacing techniques are presented in this book through simple language, excellent graphical annotations and a large variety of solved examples. Spread across 26 chapters, this book starts with the internal architecture of 8051, and then explains all instructions with examples of applications. In-depth discussions on interrupt-handling features are followed by the techniques of interfacing 8051 with the external world through different types of motors, relays, sensors, ADC/DACs, memory devices, keyboards, displays, etc. As most of the embedded systems are battery-powered, power-saving schemes play a major role in considerations of these system designs. Hence, an entire chapter is devoted to explaining power management using 8051. One full-length design example explaining both hardware as well as software aspects of a home protection system using 8051 is presented as a case study. Discussions are concluded by a chapter on advanced microcontrollers such as the AVR.