Information Technology [2 Mark Questions]

Random Access Memory (RAM) also called the read/write memory as data can be read and write to it. It is a temporary memory. The contents of the RAM are accessible only as long as the computer is ON. Once the computer is turned OFF, the contents of RAM are wiped out. It stores operating system routines, application programs and the data in current use are kept temporarily.
The types of RAM are SRAM and DRAM.

Read Only Memory (ROM) is a special type of memory whose contents can only be read. It is a permanent memory, so the contents of the ROM are not lost, even when the computer is switched OFF. It is normally used to store the manufacturer’s instructions.
The types of ROM are PROM, EPROM and EEPROM.

It is a device that allows a user to take an image or text and convert it into a digital tile, allowing the computer to read or display the scanned object.
It can be used for storing the documents in their original form that can be modified and manipulated later on.
It comes in a variety of size from hand-held models to desktop models which are as follows:

• Hand-held scanners They are very small which can be held in a hand. These are less expensive and less wide. Hence, in order to scan a single page image, multiple passes are required. But, their handiness is a major advantage of hand-held scanners.
• Flatbed scanners They are large and more expensive scanners that create higher quality of images. These scanners have a flat surface on which the printed image to he scanned is placed (Similar to the way a page is placed on a photocopier). They can scan a page in a single pass.
• Drum scanners They are medium size scanners with a rolling drum. The sheet is fed through the scanners so that the drum rolls over the entire sheet to be scanned (Just as the sheets are fed in a fax machine).

Distinguish between input unit and output unit are as follows:

Input Unit	Output Unit
It accepts the data and instructions frofri outside.	It accepts the result which produced by the computer.
It converts the accepted instructions and data in computer acceptable form	It converts the results, which are in a coded form to human readable form.
It supplies the converted instructions and data to the computer system for further processing.	It supplies the converted results to the user.

It is an output device similar to a printer that uses a pen, pencil, marker or other writing tool to make a design. It is generally used to generate the map of building and shopping malls. It is a computer A Patter printing device for printing vector graphics.
In the past, plotters were widely used in applications such as CAD and other print jobs. Though, they have generally been replaced with wide format conventional printers.

Laser printers are based on photocopy technology to print. They use a laser beam and dry powder ink to produce a high quality dot matrix pattern. They can print graphic images too. They are ideally used when good quality and large scale printing is required.

These printers are much quieter than impact printers as their printing heads do not strike the paper. Most non-impact printers produce dot-matrix patterns. There is no mechanical contact between the paper and the print head. These printers are comparatively faster and produce high quality output. They can be used for printing text and graphics both in black, white and colored.

LCD stands for Liquid Crystal Display. These screens are used in notebooks and laptops sized PCs. A special type of liquid is sandwiched between two plates. It is thin, flat and light weight screen made up of any number of colors. Some of the major features of LCD monitors are as follows:

1. Reduced radiation
2. Light weight
3. Less eyestrain

Biometric sensor is a device used for recognising physical or behavioural traits of an individual. This device is mainly used for security purpose and for marking attendance of employees/students in organisations/institutions. The major advantage of this device is that it eliminates the problem caused by lost IDs or forgotten passwords etc.

Barcode reader is a device which is used to read the printed code (barcode) from the products to be sold. It contains a light sensitive detector which identifies the values of the bars printed on the product and converts them into a numeric code. This barcode reader technology is used in shopping malls to identify products and generate bills.