This up-to-date and contemporary book is designed as a first level undergraduate text on micro-processors for the students of engineering (computer science, electrical, electronics, telecommunication, instrumentation), computer applications and information technology. It gives a clear exposition of the architecture, programming and interfacing and applications of 8085 microprocessor. Besides, it provides a brief introduction to 8086 and 8088 Intel microprocessors. The book focusses on : microprocessors starting from 4004 to 80586. instruction set of 8085 microprocessor giving the clear picture of the operations at the machine level. the various steps of the assembly language program development cycle. the hardware architecture of microcomputer built with the 8085 microprocessor. the role of the hardware interfaces: memory, input/output and interrupt, in relation to overall microcomputer system operation. peripheral chips such as 8255, 8253, 8259, 8257 and 8279 to interface with 8085 microprocessor and to program it for different applications.