My favourite output devices

Visual Output

          Screens and monitors

Most PC’s are connected to a monitor. The image quality depends on its size and its resolution. Screens set to a high resolution display have smaller images and lower resolution displays have bigger images. Graphics artists and architects need big, good quality displays and therefore need high-resolution monitors. The resolution is measured in pixels.

Most monitors are either CRT or TFT types.

CRT monitors are based on cathode ray tubes that fire electrons at a screen. The cathode ray tube is long, which means these types of monitors are deep and take up a lot of room. They are usually cheaper than TFT’s. Most new computers have TFT (thin film transistor) screens. These are flatter and take up less space and are very popular. They use liquid crystals to form an image.

          Large displays

If a computer image needs to be shown to large numbers of people there are several options:

Digital projectors. These can be used to project a large version of the monitor output onto a screen, so that it can be viewed by a large audience in a classroom or for business presentations. They can be portable but are often ceiling mounted.

Interactive whiteboards. Digital projectors can alsoproject on to special screens called interactive whiteboards. They are touch-sensitive, can be written on using a stylus shaped pen or a finger. Handwriting recognition can be used to convert handwritten text to computer text, which can then be saved or printed. Interactive whiteboards are both input and output devices.

Plasma screens. These large screens can be used as TV’s as well as computer monitors. They are often seen in business reception areas e.g. hotels and in shopping centres. They work by illuminating tiny fluorescent lights to make the image.

           Small displays

Mobile phone screens. More and more people use their mobile phones to access the internet for various reasons. 3G phones can also display live video and therefore need a good quality image. However the tiny screens are a challenge for web designers to develop usable images and content. TV content can also be downloaded and viewed or listened to on a mobile phone.

PDAs. They generally have a larger screen than mobile phones and can be used to run word processor and spreadsheets software. They usually have touch screens and virtual keyboards operated by a stylus.

       PRINTERS

Many computer processes need information output in a paper-based format.

Laser printers – fast and good quality documents are produced. Mostly used by businesses.

Inkjet printers – They are cheaper to buy (though can be expensive to run)and are very popular, especially for home users. They tend to be a bit slower. They can be used to produce photographs using special paper.

Multi-function printers – These include a built-in scanner and can scan, photocopy, print and sometimes fax too. They usually use inkjet technology.

Dot-matrix printers – They use dot-matrix technology to print on multipart stationary e.eg continuous paper. They can be found in industry where high volume prints are needed and quality is not so important. They are much less common nowadays.

Plotters. These are used to produce large sized technical drawings e.g by engineers and architects. They are expensive and only used for specialist purposes.

Professional printers.  A professional printing company can be used to print large professional quality documents and saves office staff time and wear and tear on office printers

Photo printing. Special printers can be used to print images from digital cameras.

          SPEAKERS

They produce audio/sound output. They can be external and plugged into computers. The quality and level of volume are variable.Most laptops and monitors these days have built-in speakers. Satellite navigation systems also have built-in speakers. Built-in speakers tend to be low volume and quality. Headphones can be plugged into a computer or MPS player to hear sound that nobody else in the room can hear. Prolonged use of headphones could cause hearing damage, unless the volume is kept low.

         SPECIAL PURPOSE OUTPUT DEVICES

Output devices for people with disabilities. Large monitors which can display large font sizes and magnified images would be useful for partially-sighted people. Text can be read out as it is typed.

Out of all these output devices the inkjet printer is my favourite because it can print out photographs in colour, which enables you to get the most out of your favourite memories.

My favourite storage and media devices

Reasons for storing data

·         Basic setup information and operating systems are required for the computer to function.

·         Application software needs to be available for the user to carry out tasks.

·         Files created by the user need to be stored so that they can be used again.

·         Data may need to be transferred from tone device to another.

·         Backup copies need to be taken in case the original files are lost or have become corrupt.

File Compression

This is a way of reducing the size of files that need to be stored by compressing them. Photographs, sound and video files tend to be extremely large if they are stored in an uncompressed format, especially if they are of high resolution.

·         Backup software compresses the data that is being stored.

·         Compression can be used when transmitting files from one computer to another which would reduce the transmission time or allows more data to be fitted on to any storage medium

Types of storage

In addition to the immediate storage capacity of ROM and RAM, a computer needs backing storage for mass storage of data and programs.

Magnetic Storage:  Hard disks and floppy disks work by storing data on magnetised surfaces.

Hard disks: Most of the day-to-day storage on PC systems is carried out by the hard disk. A hard disk is made up of rotating plastic or metal disks covered with a magnetic coating on which the data is stored. Hard disks are available with very large storage capacities at a relatively low cost. They are fast, extremely reliable and robust.

Floppy disks: Floppy used to be a popular method of storage, but is no longer a practical storage method. They store data on a circular piece of magnetic film, built into a plastic case for protection. They are easily damaged and not very reliable.

DAT tapes: These tapes are small in size but can hold a lot of data. They are often used to back up servers because they are easy to take away and store at a different location to the server. They are quite slow to write and retrieve data.

Optical Storage: Optical storage devices such as CDs and DVDs use optical technology to etch the data onto a plastic-coated metal disc. Laser beams are then passed over the surface to read the data.

Flash Memory: Because of its small size it is used for portable devices such as digital cameras, MP3 Players, mobile phones

Choosing a storage device

·         Volume of data

·         Purpose of storage

·         Need for re-writing

·         Speed of recovery of data

·         Size of device

 Out of the storage devices the flash memory is my favourite because without it we wouldn't be able to store our favourite pictures , songs , contacts on our mobile phones.

My favourite Input Devices

You'll probably already know that there are many input devices for a computer, which allows you to input data in various ways. The types of data that you are familiar with will probably be text and numbers, but there are others such as still moving images and sound.

Keyboard and Mouse
The simplest input devices are the keyboard and the mouse. A keyboard is used to input data manually into a computer. The standard keyboard that is used throughout the UK is the QWERTY keyboard. However there are many different keyboards that are used to suit other countries with their languages. A mouse is a pointing device which is used to move a pointer around the screen and to select options by clicking. There are two main types of mouse, mechanical and optical. A mechanical mouse has a rolling ball and the computer senses its position on a flat surafceand requires a mouse mat, where as an optical mouse uses a light sensor to detect motion and doews not need a mouse mat.

Touch-sensitive devices
As technology has improved the invention of touch-sensitive devices has evolved, which only requires the human hands to work. Concept keyboards and touch screens are examples of touch sensitive devices. Concept keyboards are divided into areas which are labelled to suit the actual use. Special software then interprets the key press for the computer. This type of input device can also be used by children and people with disabilities. A touch screen senses when an area of the screen has been touched, either by wires embedded in the screen or by patterns of infra-red light beams. Software then interprets the signal. PDAs and graphics tablets are examples of touch screens.

Speed Recognition
This is where the user speaks into a microphone. The sounds of words are compared with a dictionary of sounds and converted into computer-readable text using speech recognition software.

Automated input
Card Readers - For example magnetic strip cards can be swiped through a  card reader machine. These are easy to read, but can't hold much data. The magnetic strip is also easy to scratch.

Smart Card - A smart card such as a chip and PIN credit card. The computer chip built into the card can hold more data than a strip card.

RFID - This stands for Radio Frequency Identification which uses radio waves to transmit a unique serial number as a form of ID for objects.

Scanners - These are used to turn paper-based pictures or documents into digital images. Examples are flat-bed scanners, barcode scanners, hand-held scanners.

OMR - This stands for Optical Mark Recognition which uses a light beam to sense the position of the pencil or other marks on a piece of paper.

OCR - Optical Character Recognition is where a paper-based document is scanned and each part of the image is compared to a dictionary of known letter shapes.

Barcode Readers - A pattern of black and white lines which represents a number. They are often used in electronicpoint of sale. The barcode is scanned and the product number acts as a product key for the product in the stock database.

Out of all of these input devices the mouse is my favourite input device because without it our life would be much harder. The mouse is used as a pointing device and allows you to click on icons and options. It is much easier to just get to a program by just clicking it's icon than having to use only the keyboard tabs to navigate on the computer, which would take much longer and would become a headache if you didn't know all the shortcuts.