Microprocessor A microprocessor is a universal logic IC chip which can carry out a set of actions in sequence by inputting instructions. The term microprocessor means the CPU (central processing unit) of a small computer system. According to the set of instructions, microprocessors can execute ,they are classified into RISC(reduced instruction set computer) and CISC(complex instruction set computer). A microprocessor consists of the ALU(arithmetic/logic unit)which performs arithmetic calculations and makes logical decisions. Digital information is carried by bus connections. A bus is a set of lines, each line is used for a single –bit signal, that connects many units. Other important elements are tri-state buffers, which can pass a 1 and a 0 or they can disconnect their output. Microprocessors are made by using techniques similar to those used for other integrated circuits. The room used for microprocessor fabrication is called clean room, because the air in them is accurately filtered and almost completely free of dust.