The present book covers three parts viz. the hardware, software and the applications of microcomputers, focusing on the most widely used device, the INTEL 8085/8085A besides surveying the devices based on INTEL 8751, 8086/8088/80386, ZILOG Z80/Z800/Z80000. MOTOROLA MC 6809/68701 etc. An introduction to the bit-slice processor along with its design features has been added. A microprocessor-based system requires understanding of both hardware and software, here, emphasis has been laid on software so that one can cope with the rapid expansion in the field of microprocessor. The book also explains each mnemonic to make the reader understand physical phenomena taking place in the hardware circuitry of microprocessors. Interfacing techniques have been explained clearly with the aid of diagrams, charts table alongwith the input/output devices and controlling and peripheral devices. This book has well defined coverage on single chip microcomputers (microcontrollers) emphasizing on the architecture, memory organization, programming technique and a large number of programming examples. iAPX186, 286, 386, 486 and the Pentium processor considering their hardware details and software. Different CISC, CRISC, RISC systems have been discussed with their comparative study, merits and demerits. The book is intended for undergraduate and postgraduate students of electrical engineering, electronics and allied fields of engineering and sciences. Researchers and Professionals will also find this book beneficial.