учебник 3 курс ICT

3. Control unit functional diagram

2. Make notes about the features of the computer that you would like to have and describe it.

FUN AND GAMES SECTION

Vocabulary quiz.

1. In groups of three, write answers to these questions. The winners are the group that answers the most questions correctly in three minutes.

1.What are the main parts of the CPU?

2.What is RAM?

3.What memory section is permanent and contains instructions needed by the CPU?

4.What information is lost when the computer is switched off?

5.What is the meaning of the acronym SIMM?

6.What is a megahertz?

7.What is the ALU? What does it do?

8.How can we store data and programs permanently?

61

2. Solve the clues and complete the puzzle with words from the Key Information Section.

Down: The brain of a computer

HUMOR SECTION

What does each of the cartoons imply? Why is it funny, in your opinion? Explain its humour.

62

collar of the tube which deflect the electron beam. The beam scans across the top of the monitor from left to right, is then blanked and moved back to the left-hand side slightly below the previous trace (on the next scan line), scans across the second line and so on until the bottom right of the screen is reached. It is again blanked, and moved back to the top left to start again. It scans the screen in a continuous sequence, similar to the movement of our eyes when we read, but much faster - this process draws a complete picture. This sequence is repeated 50-100 times per second,

depending on the system. If the rate of this repetition is low, we can perceive a flickering, unsteady screen, which can cause eye fatigue. 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, they are distortion-free while typical CRTs are curved, which may cause image distortion, so they are replacing CRTs. Users talk of benefits such as more desk space, how easy they are to adjust for tilt

and height, crisper, clearer images and the total elimination of screen flicker. Manufacturers offer compatible flat screens including built-in stereo speakers, headphone connection, and a USB port. Some models can also be removed from the stand and mounted on the wall. They come with stylish designs for a variety of applications.

Plasma displays have many advantages: high-contrast images and bright colours, generated by a

Home cinema enthusiasts set up systems with a DVD recorder, speakers for surround sound, and a rear projection TV, which has the video projector and the screen within a large TV box. It‘s a real cinema experience.

Video projectors are used when audiovisual presentations are on a laptop connected to a frontscreen projector which displays the images on a distant screen or white wall.

Portable DLP projectors are used for business presentations. This is a digital light-processing device which creates the image with millions of microscopic mirrors arranged on a silicon chip.

Sound output

Computer speakers, or multimedia speakers, are external speakers, commonly equipped with a low-power internal amplifier. The standard audio connection is a 3.5mm (1/8 inch) stereo jack plug often colour-coded lime green for computer

64

sound cards. There are also USB speakers. More sophisticated computer speakers may have a 'subwoofer' unit to enhance bass output. Some computer displays have rather basic speakers builtin. 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. In the context of telecommunication, the term headset is used to describe a combination of headphone and microphone used for two-way communication.

VOCABULARY PRACTICE SECTION 1

1.Decide whether these statements are true or false. Correct those which are false.

1.Most computers still use CRT monitors.

2.Typical CRT-based displays occupy less space than LCDs.

3.Liquid-crystal displays are curved.

4.Flat LCD screens are becoming very popular.

5.LCD technology consumes less power than CRT technology.

6.Flat screens are cheaper than CRT monitors.

65

3. Complete this extract from a workplace health and safety guide using words from the box. Then choose the correct verb forms from the options.

footrest ache swivel idea copyholder strain repetitive

The following guidelines can help you avoid the common pitfalls of daily computer use – eye 1……. , back 2……. and 3……. strain injury (RSI).

Get/Don‘t get a comfortable chair that supports your lower back.

Ask/ Don‘t ask for a 4……. to place under your desk and a tilt and 5……. stand for your screen.

Position your keyboard correctly: your arms should/shouldn‘t be perpendicular to the desk surface.

It‘s a good 6……. to take regular breaks in order to rest your eyes.

You should/shouldn‘t work from hard copy documents without using a 7…….

Forget/Don‘t forget to clean your screen regularly.

KEY INFORMATION SECTION 2

Bits for pictures

The characters and pictures that we see on the screen are made up of dots, also called picture elements (pixels).

In a bit-mapped display, the dots displayed on the screen correspond, pixel by pixel, with bits in the main memory of the computer. The bits are held in an area of the memory called the 'refresh

66

represents one pixel on the screen and can be either 'on' or 'off' (black or white). On colour systems, each pixel is a certain combination of the three primary colours: red, green and blue.

Refresh buffer (memory) Display

The total number of colours which can be shown on the screen is called the colour palette. The size of this palette depends on the graphics adaptor, a separate video card that converts the bits into visual signals. A graphics adaptor with 1 bit per primary colour can generate up to 8, or 23, colours, as you can see from the table. A graphics adaptor with 8 bits per primary colour can generate 16.7 million colours.

One bit per primary colour

Performance characteristics of monitors

The performance of a monitor is measured in the following parameters:

Resolution - the clarity of the image depends on the number of distinct pixels contained on a

67

Colour depth - the number of colours a monitor can display. For example, a VGA monitor produces 256 colours, enough for home use; a SuperVGA can produce up to 16.7 million

colours, so is ideal for photographic work and video games.

Refresh rate is the number of times in a second that a display is illuminated. If a monitor has a

refresh rate of 75 Hertz (Hz), it means that the screen is scanned 75 times per second. If this rate is low, you will notice a flicker, which can cause eye fatigue. Maximum refresh rate is limited by response time.

Response time is the amount of time a pixel in a monitor takes to go from active (black) to

inactive (white) and back to active (black) again. It is measured in milliseconds. Lower numbers mean faster transitions and therefore fewer visible image artifacts.

Contrast ratio is the ratio of the luminosity of the brightest color (white) to that of the darkest

color (black) that the monitor is capable of producing.

Power consumption is measured in watts.

Aspect ratio is the ratio of the horizontal length to the vertical length. 4:3 is the standard aspect

ratio, for example, so that a screen with a width of 1024 pixels will have a height of 768 pixels. If a widescreen display has an aspect ratio of 16:9, a display that is 1024 pixels wide will have a height of 576 pixels.

Viewing angle is the maximum angle at which images on the monitor can be viewed, without excessive degradation to the images. It is measured in degrees horizontally and vertically.

VOCABULARY PRACTICE SECTION 2

1. Complete these display screen specifications with the missing words. The first letter is given.

1.r……. : 1280x768

2.a……. ratio : 16:9

3.s……. size: 19‖

4.c……. depth : 16.7 million

5.b……. : 400 cd/m2

68

2. Match each term with the correct definition.

3.Decide which words are being defined in these extracts from an ICT dictionary.

1.One of the small units that make up an image on a computer or

4. Using the information in the passage and the illustrations, match the terms in the box with the appropriate explanation or definition.

69

5. Tables often include abbreviations and technical words that are not easy to understand. Look at this table and the explanation of Monitor A's specifications. Using the example, describe Monitor B.

You get a resolution of 1024 by 768 pixels.

It has a built-in power feature that saves a lot of energy consumption.

6. Complete the technical specs of this monitor with words from the Key Information Section.

70