In manual data processing human beings are the processors. Our eyes and ears are input devices. We get data either from a printed paper, that can be read using our eyes or heard with ears. Our brain is the processor and it can process the data, and reach in a conclusion known as result. Our mouth and hands are output devices. In electronic data processing the data is processing with the help of a computer. In a super market, key board and hand held scanners are used to in. put data, the CPU process the data, monitor and printers (Bill) are output devices.