Computer Input-Output System and Devices

Computer Input Output Devices

Computer Input/Output system

The input-output devices are the connections of a computer to the outside world. There can be innumerable devices connected to a computer that do the input or output or both functions. The input/ output blocks take care of data transfer activities between devices and the computer. The devices are also called peripheral devices. As the name suggests, an input device is one, which senses external data and converts that to computer understandable form. keyboard, mouse, digitizers, scanners, etc. fall in this group. In the same way, an output device interprets the data coming from inside the computer, to the outside world, in human-readable form, so that the user can understand the messages and the results of calculations. Video display units (TV monitors), printers, plotters, etc. fall in this category. 

There are some categories of devices that act as both input and output devices. In a true sense, they neither interpret the internal data in human-readable form nor do they sense data from physical objects other than their own media. Data and instructions already in the machine.

The understandable form can be stored in them (the computer can retrieve the prerecorded data and instructions from them). Basically, they act as a storage device for keeping data and programs. They are very useful because of their large storing capacity and as the computer can retrieve data easily from them. The primary memory of any computer is volatile, i.e, its contents are lost as soon as the power goes off. without these storage type input and output devices, no developed program could be kept for repeated use, no data could be saved for future use. However, as the architecture restricts, no program can be executed from them directly without bringing the program and data in the primary memory. These devices, thus, are called secondary memory or secondary storage. Hard disks, floppy disks, tape drives, cassettes, compact disks (CD) fall in this group. They are also called bulk storage devices. 

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