"Microcontroller 8051" provides the reader an indepth understanding of microcontroller 8051 in terms of the necessary theory and its practical usage and presents the hardware and software features of the microcontroller 8051 in a lucid manner. The conceptual difficulties that exist in understanding the subject have been overcome with simple illustrations that help the reader grasp the subject effectively. The assembly language programming have been dealt at length with a large number of examples and worked out problems. Interfacing of microcontroller 8051 with the devices like LCD/LED, Keyboard, Sensor, ADC and DAC etc., are explained in a reader friendly approach. A large number of worked out examples provided in each chapter are helpful to the reader in mastering the programming and application aspects of microcontroller 8051.