A computer keyboard is an important device that allows a person to enter symbols like letters and numbers into a computer. It is the main input device for most compute.
Originally computer monitors were used for data processing and television receivers for entertainment; increasingly computers are being used both for data processing and entertainment. Displays exclusively for data use tend to have an aspect ratio of 4:3; those used also (or solely) for entertainment are usually 16:9 wide screen, Sometimes a compromise is used, e.g. 16:10
A graphics tablet (also called pen pad or digitizer) consists of a flat surface upon which the user may "draw" or trace an image using an attached stylus, a pen-like drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor. Some tablets, however, come as a functioning secondary computer screen that you can interact with images directly by using the stylus.
Bar code Reader
A bar code reader (or bar code scanner) is an electronic device for reading printed bar codes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all bar code readers contain decoder circuitry analyzing the bar code's image data provided by the sensor and sending the bar code's content to the scanner's output port.
(also called Optical Mark Reading and OMR) is the process of capturing human-marked data from document forms such as surveys and tests.