9. Bits - basic units of memory: binary notation, binary digit, byte, kilobyte, megabyte, gigabyte). What is a standard system for the binary representation of characters?

Information is processed and stored in computers as electrical signals.

To represent these two conditions we use binary notation in which 1 means ON and 0

means OFF. This is the only way a computer can 'understand' anything. Everything about

computers is based upon this binary process. Each 1 or 0 is called a binary digit or bit. 1s and 0s are grouped into eight-digit codes that typically represent characters (letters, numbers and symbols). Eight bits together are called a byte.

The majority of computers use a standard system for the binary representation of characters.

This is the American Standard Code for Information Interchange, known popularly as ASCII (pronounced 'ask-key'). There are 256 different ways of combining 0 and 1 bits in a byte. So they can give us 256 different signals. However, the ASCII code only uses 128 bytes to represent characters. The rest of the bytes are used for other purposes.

The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc. Each letter of the alphabet, and many symbols (such as punctuation marks), as well as the ten numbers, have ASCII representations. What makes this system powerful is that these codes are standard. In order to avoid astronomical figures and sums in the calculation of bytes, we use units such as kilobytes, megabytes and gigabytes. One kilobyte is 1,024 bytes (2№є) and it is represented as KB, or more informally as K. One megabyte is equivalent to 1,024 KB, and one gigabyte is 1,024 MB.

We use these units (KB, MB, GB) to describe the RAM memory, the storage capacity of disks and

the size of any application or document.

10. How does a monitor work? Types of monitors (CRT, TFT-LCD, Plasma displays). Main functions of video projectors, multimedia speakers. What is the difference between earphones, earbuds, stereophones, headsets and cans?

It is a piece of electrical equipment which displays images generated from the video output of computers, without producing a permanent record. The monitor comprises the display device, simple circuitry to generate and format a picture from video sent by the signals source, and usually an enclosure. The monitor is controlled by a separate circuit board, known as the display adaptor. The video card processes images and sends signals to the monitor.

Older monitors are based around a cathode ray tube (CRT), similar to a traditional TV set. At the back of the tube there is a negatively charged cathode and three electron guns - each gun shoots out a beam of electrons for each of the primary colours: red, green and blue. These electrons strike the inside of the charged screen which is coated with substances called phosphors (there are different materials for each of the three colours) that glow when struck by electrons and create colours.

CRTs are cheap, but they are heavy, can flicker and emit radiation.

Most newer monitors typically consist of a TFT-LCD. A Liquid Crystal Display (LCD) is made from flat plates with a liquid crystal solution between them. The crystals block the light in different quantities to create the image. Active-matrix LCDs use TFT (thin film transistor) technology, in which each pixel has its own transistor switch. TFT systems offer a wider angle of vision and high-quality images, they are flat and take up less space, use less power than CRTs,

Plasma displays have many advantages: high-contrast images and bright colours, generated by a plasma discharge which contains noble, non-harmful gases. Gas-plasma TVs allow for larger screens and wide viewing angles, perfect for movies.

Video projectors are used when audiovisual presentations are on a laptop connected to a front-

screen projector which displays the images on a distant screen or white wall.

Sound output

Computer speakers, or multimedia speakers, are external speakers, commonly equipped with a low power internal amplifier. More sophisticated computer speakers may have a 'subwoofer' unit to enhance bass output. Laptops come with integrated speakers. For some users, a lead connecting computer sound output to an existing stereo system is practical. This normally yields much better results than small low-cost computer speakers.

Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source. They are also known as earphones, earbuds, stereophones, headsets or, informally cans.