GNVQ ICT - Intermediate

Unit 3 - Hardware and Software

[ Hardware ] [ Software ] [ Health and Safety ] [ Macros ] [ Website ] [ Templates ] [ The Test ] [ 2007 Tasks ]

Hyperlinks:

On this level:

Input
Output
Processing
Storage

On the level below:

Output devices

Monitors or Visual Display Units (VDUs)

The two main types of monitors are:

CRT monitors (CRT = Cathode Ray Tube) which look like and use the same type of technology as a standard television.  These are usually in colour and range in size from 14” up to 21”.  The largest sizes of monitors are for very detailed design work or graphics and desktop publishing, whilst the smaller monitors are fine for normal office uses such as word processing and working with spreadsheet worksheets.

LCD (Liquid Crystal Display) – now usually called TFT (Thin Film Transistor) displays – these are flat screens which are becoming increasingly popular.  This is the type of screen fitted to laptop and notebook computers – and most are now colour screens.  Sizes vary from 14” to 21” or larger – but this type of monitor is much more expensive than CRT monitors.

Monitor Issues

When buying a monitor there are several issues which are important.  Much depends on the purpose of the monitor – ie. what it will be mainly used for.

Graphics card/adapter – the monitor must receive data in the correct format to display.  It is linked to the computer using a special cable and connector.  The connector can either be plugged directly into the computer’s motherboard (main system circuit board) or into a special graphics adapter that is plugged in to the motherboard.  These graphics adapters or cards can be very expensive – but can make a huge difference to the quality of the display.  For example a good quality graphics card will be useful for working on detailed designs of page layouts in desktop publishing.  They are also used by “serious” PC game players.

Size of screen – the screen size is measured diagonally across the screen – so 14” is measured from the bottom left corner to the top right corner.

Resolution – the quality of the picture on the screen is determined by the number of dots (pixels).  In the early days of colour monitors most were set to 640 dots wide by 480 dots high.  This increased to 800 by 600 – and most recently to 1024 by 768.  The highest resolution monitors can display 9.2 million pixels at 204 pixels/inch for exceptional clarity and detail.

Number of colours – in the 1980s computer monitors were often only able to display up to 16 colours at any one time.  Now almost all can display up to 16 million colours (known as “true colour”).

Interlaced/non-interlaced – The screen on a monitor is made up of tiny pixels.  Each row of pixels is redrawn frequently (many times each second).  On an interlaced monitor every second row is drawn – and then the alternate rows are drawn.  On a non-interlaced monitor every single row is drawn each time.  This is important.  A non-interlaced monitor is better as it is less likely to cause eyestrain.  Eyestrain can be caused by monitors that are interlaced.

Refresh rate – this is the speed at which the dots (pixels) are redrawn on the screen.  The higher the refresh rate the faster the screen is refreshed.  A low refresh rate can cause eyestrain – whilst a high refresh rate is usually better.  Some cheaper monitors may work only at low refresh rates – and this can be a problem – especially if the graphics adapter is able to send data at a higher refresh rate.

Printers

Laser printers

Ink-jet printers are much cheaper to buy, offering black and white or colour printing with reduced levels of quality and speed.  However, the ink cartridges are sometimes almost as expensive as the printer to buy.  The cheapest inkjet printers can cost as little as £30 whilst the colour ink cartridges can cost £25 each to replace!

Dot-matrix printers are not so common today.  They now cost as much as a laser printer.  They are comparatively noisy and low quality but are cheap to run and ideal for draft copies.  They can also be used to print onto multi-part forms so that several copies of a document (such as an invoice or delivery note) can be made at the same time.

Plotters

A plotter can be used to produce high quality, accurate, A3 size or bigger drawings. They are usually used for Computer Aided Design (CAD) and Computer Aided Manufacture (CAM) applications such as printing out plans for houses or car parts.  The one shown here costs over £6000 (Nov 2003).

Speakers

Computers are increasingly used as the centre of home entertainment – with DVD drives and “surround sound” speaker systems.  Speakers can be plugged into the sound output port of a computer.

Data projectors

A data projector sends the image through a lens to enlarge it and project it onto a screen.  These can be used in schools (sometimes with an “interactive whiteboard”) or in places where a group will be watching the output together.  Some pubs and clubs use a type of data projector to show sport and other entertainment on a “large screen”.

© Hyde Technology School - Non-commercial use by other educational establishments is welcome.  

Please email your comments to mail@ictgnvq.org.uk    Created by K C Parry - Please email your comments to kcparry@ictgnvq.org.uk