Page 19 - Computer Science V2.0 Class 11

OCR Keyboard

Mouse Scanner

Input Devices

Bar Code
Reader Trackball

MICR
Joystick

Touch Panel Touchpad
Fig 1.4: Input Devices

Name the input device for the following:
1. Converts an image on paper to digital form.
2. A device used to automate the evaluation of multiple-choice questions, whose answers have been
marked by darkening circles against the correct answers.
3. A device that scans the fingerprint of employees for attendance.

1.3 Output Devices

The output devices receive data from a computer and deliver the desired output on a suitable device for a user. It
converts digital data into a human-understandable form. Some of the commonly used output devices are described
below (see Fig 1.5):

1.3.1 Monitor

A monitor or a Visual Display Unit (VDU), popularly known as a screen, is the most commonly used output device.
The monitor is organised in the form of picture elements (pixels), often arranged in a rectangular array. A pixel is the
smallest unit of graphical information on the computer screen. The size of a monitor is expressed in terms of the length
of the diagonal of the display unit. Thus, a 15-inch (38 cm) display may be 12 inches (30.48 cm) wide and 9 inches
(22.86 cm) high and may comprise 1024×768 pixels. Pixel dimensions (say, 1024×768) are also called pixel resolution.

1.3.2 Printer

A printer is an output device that produces the output on paper. Paper output is also known as hard copy and often
includes text and images. Nowadays, laser printers are most popular as they produce high-quality permanent output.
In contrast, thermal printers, often used for billing at restaurants, petrol pumps, and several shops, produce outputs
that fade away with time. Previously, dot matrix printers were very popular because they produced low-cost outputs.

1.3.3 Plotter

A plotter is an output device used for printing high-quality images and drawings such as maps, architectural layouts
and designs.

Computer Fundamentals 5