Computers consist of electronic components assembled in a design or "architecture" that will perform necessary functions of input, output, computation and control (control of both the computer itself and of attached peripheral devices that perform input and output functions and store the files).
In the past, electronic components were expensive, so a minimum number were used in a single processor that alternately performs input, control, processing and output. Besides, the first generation of computers, operated by means of vacuum tubes or valves, were relatively bulky and energy consuming. The first major innovation, leading to micro-electronics was the discovery of transistor, a product of solid state physics, which used semiconductor materials. The most important development of these today is based on the non-metallic element 'silicon'. Being much smaller than the vacuum tube, the transistor quickly replaced it in all electronic equipment. However, transistors and other equipment had to be wired together and a single piece of equipment might have thousands of such components. The wiring and assembly of such elements were a delicate and costly process. This naturally paved the way for research towards the concept of integrated circuit (IC). At first IC's were simple but, as the technology developed, they rapidly became smaller and more complex. This led to the miniaturisation and refinement. The central feature of micro-electronics is the development of micro-processor, a special form of IC with functions of arithmetic, logic and control - similar to those of Central Processing Unit (CPU) of a computer and contained in a single chip. In addition, the microprocessor includes units to interpret instructions from the stored programme to supply the control memory the information necessary to retrieve instructions and send out data as required.
The microprocessor is the building block from which modem computer systems are assembled. The microprocessor uses very, little energy and has few environmental requirements of older machinery. Air conditioning, for example, might not be necessary for a general purpose computer using microprocessor technology. The practical significance of this is that it is mow possible to bring the computer to the problem instead of bringing the problem to the computer. The aspects referred to above form a major hardware component of a computer.