The book is written for an undergraduate course on the 8085 microprocessor and 8051 microcontroller. It provides comprehensive coverage of the hardware and software aspects of 8085 microprocessor and 8051 microcontroller. The book is divided into two parts. The first part focuses on 8085 microprocessor. It teaches you the 8085 architecture, instruction set, Assembly Language Programming (ALP), interfacing 8085 with support chips, memory and peripheral ICs - 8251, 8253, 8255, 8259, 8237 and 8279. It also explains the interfacing of 8085 with data converters - ADC and DAC - and introduces a temperature control system and data acquisition system design. The second part focuses on 8051 microcontroller. It teaches you the 8051 architecture, instruction set, programming 8051 with ALP and C and interfacing 8051 with external memory. It also explains timers/counters, serial port and interrupts of 8051 and their programming in ALP and C. It also covers the interfacing 8051 with data converters - ADC and DAC, keyboards, LCDs, LEDs, stepper motors, servo motors and introduces the washing machine control system design.