macalvey/teachnet/bits& bytes 2005 1 bits and bytes! concepts of ict explained

MACalvey/Teachnet/Bits& Bytes 2005

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Bits and Bytes!

Concepts of ICT explained


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A computer..?

• Job specification? Desktop publishing, video editing, sound editor, internet browser, calculates wages......

INPUT PROCESSESOUTPUT

A computer accepts Input, Processes it in some way, then displays or outputs the information.


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Types of Computers

Mainframe:

• Expensive with large storage capacity

• Can cope with very high volumes of transactions

• Typically used by banks, insurance companies, government organizations and large corporations

• Hold vast databases of information which can be accessed quickly and updated by a large number of users at the same time and support a large number of peripherals

• Expected to run 24 hours a day, 365 days a year


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The PC/ Personal Computer

• Types: Desktop/*Laptop or Notebook/ Personal Digital Assistants (PDAs)/Palmtop computers

• * Laptop - Portable/Own integral screen and keyboard/May have own rechargeable batteries or require electric power

• Main uses of PC’s are as desk-top business computers used for word processing, small business accounts, financial planning, or as home computers.

• Capable of stand alone or networked use, possible to link PC’s together to share storage facilities, printers, or files of information.


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Network server: Administers, supports and

protects security of a computer network

Dumb Terminal - An input or output device with no processing power of it’s own,

Consists of a keyboard, display screen and a communication link to a mainframe computer.

Accepts input from user, displays results, processing done by server.

Intelligent terminal - a terminal which retains a program and allows processing of data to be carried out without further access to the host computer.


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Hardware

The physical components that make up a computer system

Includes – monitor,

– keyboard,

– cables,

– memory,

– printer and the case containing the computer itself (the processor)


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Software

Term used to describe the sets of instructions or programs that tell the hardware what to do and includes the programs which we use on the computer e.g. Word processing, games, encyclopedia

Two types of Software:

– System Software

– Application Software


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System software• Manages files and storage, Controls devices,

Recognizes input, Sends output to screen, Communicates with peripherals

• Main piece of systems software is the OPERATING SYSTEM.

• Operating systems include DOS, UNIX, Windows 3.1, 95, 98, 2000, XP.

DRIVERS : Special piece of software to enable operating system to control hardware e.g. Certain printers require separate drivers, compatible with current operating system, to be installed before printer will work.


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OPERATING SYSTEM

Automatically loads when computer is

switched on, otherwise computer will not work. Functions

• Boots up the system , controls input and output devices, manages the transmission of data between application software, storage device and RAM.

• Translates commands received from the applications software: word processing programs, spreadsheets etc into instructions specific to the hardware

• Distributing RAM, controlling input and output devices, allowing/preventing access to authorised/unauthorised users


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APPLICATION SOFTWARE Generally Applies To Programs Written For A Particular purpose e.g. Word, Excel, Powerpoint, Access, Desktop publishing

WORD PROCESSING

• A programme specifically developed for the typing and production of letters, reports and documents.

• Unlike typewriter, text can be saved and modified.

SPREADSHEETS• Microsoft Excel - Commonly used

spreadsheet

• Excel workbooks - contains

the file in which work is done and data stored

• Each workbook contains many worksheets

• Each spreadsheet consists of columns down and rows across.

• Spreadsheets - largely are used for calculations from simple additions to complicated formulae

• Graph feature - range of options used for comparisons of data


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DESKTOP PUBLISHING

• A Programme for producing professional-quality

reports, booklets and magazines.

Publisher provides pre-designed templates for a wide range of documents: newsletters, cards, banners, flyers, brochures, calendars, advertisements.Templates can be modified or the user can create from scratch.

MICROSOFT ACCESS

•A program that enables creation of and working of databases

MICROSOFT POWERPOINT

•A program that creates visual slides for a presentation and handouts for use when addressing an audience


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Memory

• RAM (Random Access Memory)

• ROM (Read Only Memory)

• Cache Memory


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Random Access Memory(RAM)

• RAM is temporary, fast memory

• Working memory - holds lists if instructions that it is currently working on and handles work since last saved

• RAM is volatile and requires a constant supply of electric power , data is lost when the power to the computer is turned off

• Saving work removes it permanently from RAM to disk

• Additional RAM chips can be added by installing a memory-expansion card

• The more RAM, the faster the computer operates, the more programs that can be open simultaneously and the faster they perform

• A certain minimum RAM is required to install and run programs

• 64 Mb or 128Mb RAM minimum now required to run most programs


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ROM (Read Only Memory)

• A memory that holds data or special instructions for computer

operation, such as starting the computer or putting characters on the screen.

• Contents of ROM are permanently fixed when the computer chip is made

• Information in ROM remains intact even when computer is switched off

• Computer can only “read” what is in ROM, it cannot alter it

• ROM cannot be altered by the computer or programmer - the actual content of ROM is fixed at the time of it’s manufacture. ROM can only be changed by changing the computer.


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Cache memory

• A special high-speed memory area linked to the processor that the CPU can access quickly.

• Frequently used data is stored here saving the processor from having to read from the hard disk all the time. Allows the CPU to run faster because it doesn’t have to take time to swap instructions in and out of RAM.

• Measured in bytes ranging 128kB - 512kB


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Other forms of memory

• Video RAM (VRAM) used to store display images for the monitor.

• Determines how fast images appear and how many colours are available.

• Video memory chips are essential when running programs that display a lot of graphics.


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Memory Measurement

• Bit: Short for Binary Digit-the smallest unit of Data that

the computer can handle. Data is represented by on and off

states of the computers electronic circuitry.The binary digit for on is 0 and off is 1.

• Character: Combination of bits(0s and 1s) are used to represent characters:letters,digits and special symbols like:$, % etc.

• Byte: A fixed number of adjacent bits that represent characters are called a byte-this is the amount of memory needed to store one character such as a letter or a number.Eight bits are used to represent a character.

• Field: A collection of related characters.

• Record: A collection of fields that relate to a single unit is a record.

• File: A grouping of related records

• Kilobytes: equal to 1024 bytes or characters (KB)

• Megabytes: equal to 1024 kilobytes (approx. one million bytes (MB))

• Gigabytes: equal to one billion bytes (GB)


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Computer Power

• CPU Speed

• The amount of RAM

• Cache memory

• Hard disk size

• Clock speed

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C.P.U.

• The central processing unit is the little chip in personal computers that controls everything.


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Hard Disks

• Enable large amounts of data to be stored

accessed, and read at very high speeds

• Consists of magnetic storage plates encased in a hard disk drive

• The computer’s main storage device holding the files for the operating system plus the program and data files


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The System Clock

• Every microprocessor contains a system clock.Controls how fast the operations within a computer take place.

• Processing speeds are expressed in megahertz(MHz)

• The higher the MHZ speed - the faster the computer


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Systems Software Utilities

• Utilities are programs that are designed to assist with the routine tasks of running a computer system

• Examples- programs to copy or delete files, rename files, and format new disks

• Text editors (used to write and amend programs) and debuggers (used for finding errors in programs) also available.


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Graphical User Interface (GUI)• Incorporates four elements: Windows, Icons, Menus

and a Pointing Device

• Apple Macintosh Finder or Microsoft Window use a computerised desktop as the interface between the user and the operating system. Pictures or icons represent such items as disks, files and programs. A GUI has pull-down menus that allow the user to select from a predefined list of command choices. A GUI uses a mouse to allow the user to point at and select the items or commands that are required.

• GUI is easy to use icons are self-explanatory; a lot of similarity between basic functions of all Windows-based software.


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Data - Stages 3 stages:

Input Processing Output• Input: Data is input into the computer by typing on a keyboard or

using a scanning device such as a barcode reader in a supermarket

• Processing: Once data is input it is processed in the “brains” of the computer- (Central Processing Unit)

• Output: Data can be distributed to users via Soft Copy or Hard Copy

Soft Copy - Temporary, Displayed on monitor, Information vanishes once monitor is turned off

Hard Copy - Permanent, Printed copy on paper, acetate or microfilm


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Input devicesInputting methods have evolved dramatically over the years

from the earlier use of keyboard, punched cards and paper tape.

Input methods include:• The keyboard

• The mouse

• Trackerball

• Scanner

• Touchpad

• Light Pen

• Joystick

• Voice Input

• Graphics pad

• Magnetic disk and tape input

• Document readers• Web Cam

• Digital camera


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Keyboard is the slowest means of input

• Most used input device

• Its familiar

• Easy to operate

Mouse• Many different types including

cordless

• Gives fine conrol over use of applications

• Access to menus on Rightclicking

Tracker ball (track ball)

• A pointing device which you rotate to move the mouse cursor; commonly found on notebook computers


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Scanners• Scanner - used as a means of capturing an existing two-dimensional image - a

drawing or a photograph that could not be input using a graphics

pad

• image scanners divide a picture into a matrix of tiny dots each of which is stored in a file in the computer.

• It is then possible to use this file with an existing text file in order to combine pictures with text as in a newspaper

Optical Character Recognition (OCR)• Enables information to be automatically “read” from a printed document

• OCR scanners can recognise typed and neatly handwritten material.

• OCR is used by organisations like gas, electricity and credit card companies, all of whom need to process large numbers of similar documents in a short space of time.

Video scanners• The video scanner uses a video camera to capture an image for processing either of an existing

two-dimensional picture or of a three dimensinal object

• Video scanners will generally offer a higher resolution than image scanners


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Touch screens (touch pads)• Designed to avoid the use of a computer keyboard, the user

will simply touch the appropriate icon or other reference on the screen.

• Action will be sensed by the computer, and the option chosen will be acted upon.

Light Pens• Device used in conjunction with special hardware and

software that shines light on to a VDU screen to indicate a choice from a menu or to input a location in graphics work

• In libraries, bar codes are read by using a light pen or wand


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Joysticks• Input device for a microcomputer.The

stick as it moves (usually in one of eight directions) is able to control the movement of a shape on the screen. Sometimes there are 2 joysticks enabling a screen game to be played by 2 players.

Voice Input• Possible to programme a computer to

respond to voice commands

• Present voice recognition systems need to be “trained” to cope with a particular voice

• Must be restrained if the user gets a cold or has a sore throat


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Graphics pad• Used to input graphic image to a computer

• Freehand images can be input by drawing with the stylus

on the bed of the pad.

• Existing drawings may be traced by the stylus on the bed; alternatively they may be input by using a cursor similar to a mouse

• The cursor is positioned in turn over the key points on the drawing and one of the buttons on it is pressed

• The computer records these points and joins them together as necessary to define the computer image.

• When used to input existing drawings, graphics pads may also be called digitisers.

• They are used by architects to design buildings, and as part of CAD systems in engineering


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Magnetic disk and tape input• Both widely used for the storage of computerised information

• A computer storage device that looks rather like an LP record that has the same magnetic coating as an audio

• Information is recorded onto and read from the surface of the disk in much the same way as a domestic cassette tape recorder is used to record and play back music

• Magnetic tape is the computer equivalent of the reel-to-reel tapes found on professional tape recorders

• Data can be transferred from magnetic disk or tape far faster than it can be input from any other device

• Speeds of input from magnetic tape or disk are termed data transfer rates

Magnetic ink character recognition (MICR)• Enable the fast and efficient clearing of cheques

• Characters are printed in a special ink that can be magnetised to give off a unique magnetic field that enables each character to be read

• Used by the banks as a way of speeding up the cheque clearing system- input speeds can be anything up to 2000 cheques a minute


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Card Readers• A device that reads information held in the form of a magnetic strip on a plastic card e.g. Credit card, ATM card

Bar-code readers:• An arrangement of vertical bars and spaces that can be read by an optical

scanner and used as a means of identifying products or stock items• Seen on most products purchased in supermarkets, inside library books, and on

such items as freezers and computers. In supermarkets, each product carries a unique bar code that can be used both to calculate the size of the bill at the point-of-sale (POS) terminals (or check-outs) and for stock control.

• System operates from a central computer which controls the POS terminals.• When shoppers goes through a check-out, each item is passed over the scanner

which reads the bar code and refers to the central computer for the description and price.

• Information is relayed to the check-out, where it is displayed on a customer panel printed on a receipt. Stock level for the item purchased will be reduced , providing management with up-to-date stock information and enabling more efficient stock control and ordering.


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Document readers• Can be read by humans as well as by machines

• Used where there is a need to be able to process large volumes of similar documents, like cheques or gas bills Automated processing of cheques quickly

• Computer marking of multiple choice answer sheets

• Reading of large volumes of credit card payment slips

Web Cams• Allows two way communication including sound and video as well as

text

Digital cameras• Images are stored digitally in memory in camera

• Pictures can be transferred to computer and edited digitally


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Computer Output

Output: Once the data has been processed, information can be distributed to users.

• Computer output can take the form of a display on a screen,

a print-out, or transfer of information on to a magnetic tape or disk.

Most output falls into one of two categories: hard copy or soft copy.


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Hard copy is output in a permanent or touchable

form e.g. printed form such as on paper or microfilm. May be produced either on separate sheets or on continuous stationary taking the form of folded and perforated lengths of paper

Soft copy is information that is displayed visually on a screen or monitor - temporary: once the monitor is turned off or new information is required, the old information vanishes.

Also can be in audio form, as in speech or music


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Visual output

• Most common form of soft-copy output is information displayed on a screen or cathode-ray tube(CRT)

• The VDU enables a user to input information to a computer by using a keyboard, mouse or touch screen facilities and to view output on a CRT

• Two factors limit the use of the CRT; its weight and the amount of power it consumes

• Liquid-crystal displays (LCDs) similar to those found on some digital watches are both light and economical enough to be widely used for portable computers


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Computer output on microfilm (COM)• As an alternative to printed output, another form of hard

copy is computer output on microfilm or microfiche

• COM is the recording of what would otherwise be printed output direct in reduced form on to either rolls or sheets of photographic film

• Microform can store documentary information with textual and graphical content

• Structure can be either microfilm (a continuous reel) or microfiche (a grid pattern)

• Microform reduces storage space requirements by approximately 95% of that required by paper documentation


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Audio outputCovers the range from the simple ‘beep’ to full speech

synthesis.Speech synthesis is the production of a sound corresponding to spoken words and it is of great use where a user is unable to look at a CRT or is occupied with another.

Computer Speakers

Have the same function as hi-fi music speakers used in the home stereo systems.Differ from conventional speakers in that they are self amplified and magnetically shielded.Most speakers are AC powered and have separate volume tone controls.


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Printers

Two most common types of printers

• Inkjet Printers

• Laser Printers

*Also third category - Matrix Printers


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Ink-jet printers

• Work by using tiny jets to spray ink at high speed onto the paper

• Forms characters by projecting the ink from the small ink nozzles (the same way as by the dot-matrix printer) on to the paper - for this reason are termed a non-impact printer.

• Ideal for low volume printing with high quality where speed is not priority

• Major advantage over a dot-matrix printer is low level of noise

Laser printers• Shares the same image-printer technology as the photocopier.

• Print image is produced by a laser beam which scan across the print drum, line for line as the print cylinder rotates.

• High quality at high speed


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Dot-matrix printers

• Gets name from way in which a number of needles in the print head are used to print text as a series of dots using a carbon ribbon.

• The more pins the print head has, the higher the quality of print

• The speed at which a dot-matrix printer is able to operates depends on which typeface is being printed

• Typical speeds may range between 40 and 500 c.p.s according to the print quality.

• Noisy and not high quality

• Suitable for high volume/low quality printing e.g. printing company payslips

• Widely used as a micro-computer peripheral


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Thermal printers• Use heat to transfer the image from the print head to the paper.

• Text and images are made up from a series of dots, in common with

other matrix printers, but with this process the print head may be either a fixed array of thermal elements

Daisy-wheel printers

• This printer takes its name from a flat disc with a number of stalks or petals radiating from its centre each of which has a character at its tip.

• Daisy wheel rotates at high speed and the petals are pushed on to a ribbon which, in turn transfers the characters to the paper.

Line printer

• Gets its name from the way in which it prints a line of text at a time.

• Two types- chain printer and the drum printer.

• Main feature is their speed, the fastest printing text at around 5000 lines per minute. This is achieved by hitting the paper against the character and printer ribbon.


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Graph plotters

• An output device similar to a printer but normally

allows printing of larger images

• The graph plotter is a specialist device designed to produce high-quality pictures and designs.

• Unlike matrix printers, a graph plotter reproduces the human action of drawing by using a pen.

• Widely used by architects and designers of all kinds

• Two types of graph plotter- flatbed and drum


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Peripherals

A Peripheral is any device that is connected to and controlled by a computer but external to the CPU etc.

Peripherals include:

• Printers

• Loudspeakers

• Scanners

• Digital camera

• Microphone


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Storage

Primary and Secondary Storage:• The Term primary storage (main memory) refers to RAM

• Secondary storage is auxiliary storage - any storage device designed to retain data and instructions (programmes) in a relatively permanent form.

• Secondary storage is non-volatile, meaning that saved data and instructions remain intact when the computer is turned off.


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CD-ROM Compact Disk Read Only Memory• Widely used for reference material and training purposes, has huge

storage capacity

• Ideal for storing all forms of images including video sequences which take large amounts of storage space

• Not used for storage of documents which require regular updating.

• Speed of CD ROM drive is regularly being improved

• Standard CD-ROMS can only be written to once, CD-RW disks can be written to more than once

• A CD-writers/burner used to record or copy to a CD

• CD-ROMS now being over taken by DVDs (Digital Versatile Disks)


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Diskettes

• A diskette or floppy disk stores data and programs as magnetised spots

• The disk is contained in a plastic case to protect it

• Diskettes are sometimes called “floppy” because the disk within the

envelope or case is flexible, not rigid.


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Zip Disk/Zip Drive:

• A removable disk, capacity of 100 - 250 MB

• Can be internal or external

• Popular for keeping backups and for transferring large files between computers


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Electronic Commerce

E-Commerce a generic term for all forms of business

transactions on the Internet. The potential to advertise and sell ones `product` via a web site to mass audiences has limitless appeal.

• The 7 most popular buys on-line are: Books, CDs, Travel, Music, Electronics, Computer hardware and Clothing. Books sales on-line phenomenal growth eg. Amazon.com. CDs from America half the local price; however, delivery cost must be considered.

• lastminute.com specialise not only in cheap travel but also in occasional purchases like cars or mobile phones.

• Shopping on-line using a credit card is relatively safe. It is advisable to use e-commerce sites that keep your card details on a secure server so you don’t have to send them each time you make a purchase. Ensure that your browser is set up for secure connections to the internet. A padlock displaying on the status bar of the program when you connect to a secure server indicates that your data is secure.


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Requirements for connecting a Computer to the internet

• A computer with a fast processor, 16-128MB of RAM, up to 100MB of free hard disk.

• A Modem (unless broadband is available)

• A Telephone line

• An Internet Service Provider (ISP). Modem via the telephone line will link to the internet through the computer system of the service provider.

• Connection Software


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Data Protection Act 1984• Safeguard the privacy of the individual

• Legislation protects personal data handled in computers

• Aim to control the immense potential for misuse of information that arises when personal data is stored in computers.

- Once data has been transcribed from paper files into a form that is easily readable and accessible by computers, it is an inexpensive and easy task for the data to be extracted from one record and correlated with personal data concerning the same person from another file - infringement of privacy.


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Requirements of organisations that maintain

personal records on computers:• To declare and/or register the use for which data is stored• Must make information available to those authorised to receive without undue

delay or inefficiency

• Provide the data subject with a right of access to data concerning himself on their computer

• Keep information secret from those not so authorised in such a way that the cost of unauthorised disclosure would exceed the value of the information to the illegitimate recipient.

• Maintain a prescribed minimum level of electronic and physical security in their computer installations - System may involve physical security (safes, locks entry cards) for access to disks and passwords and also the technique of cryptography and authentication.

• Not to transmit personal data to any organisation that does not have similar controls over misuse of data

• The OECDS has also drafted a convention of similar effects


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Repetitive strain injury (RSI):

• Also known as repetitive motion injury and cumulative trauma disorder is

the name given to a number of injuries resulting from fast, repetitive work

• RSI causes neck, wrist, hand, and arm pain.

• RSI problems can result from prolonged computer keyboard use

• An RSI called carpal tunnel syndrome is particularly common among young people who use computers and certain types of scanners intensively. This syndrome involves damage to nerves and tendons in the hands.


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RSI Causes:• Repetition and duration: Prolonged, constant and

repetitious movements such as typing irritate

tendons and nerve casings, causing them to swell.

• Force: The harder you hit the keys, the more likely to suffer injury.

• Joint angle: Flexing raising, or twisting hands to reach the keys constricts the carpal tunnel.

• Prolonged constrained posture: Holding any position without moving puts excessive strain on muscles and tendons.

• Left untreated, this syndrome can cause atrophied nerve damage.

To avoid RSI:• Frequent short rest breaks.

• Plenty of sleep and exercise, maintain appropriate weight, sit up straight and learn stress- management techniques.


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Health and Safety: Computer work environment

• Prolonged use of computers can cause eyestrain,muscular strain, changes in colour perception, back and neck pain,stomach aches, and nausea.

• To reduce such physical problems,time spent at a VDU be reduced to a maximum of two hours per day of continuous screen work.

• Periodic rest breaks be granted.

• Steps taken to reduce or alleviate glare produced by overhead fluorescent lighting-glare reduction screens should be available as required by the employee.


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Systems Development

Process by which a computerised information system is created

• Stage 1: choosing the information system to be computerised

• Stage 2: Feasibility study• Stage 3: Full analysis of the system to be computerised• Stage 4: Designing how the computerised system will work• Stage 5: Writing the programs• Stage 6: Implementing the new system• Stage 7: Maintaining the System


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Computer networks

Connecting a computer to other computers in same building or in another part of the world

• Share Hardware eg. Printers• File - Sharing• E-mail / Data exchange


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Computer Based Training (CBT)

Advantages

• Flexibility of studying whenever

• Can work at own pace

Disadvantages

• No regular routine

• Student needs to be strongly motivated or highly disciplined

• Cannot consult a tutor

• No interaction with other students


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Multimedia• Global term for the developing computer technology that

can combine text, graphics, hi-fi sound, animation, and full motion video in a single high-resolution display

• Made possible by the common use of digital recording of text,

graphics, sound, and video, coupled with the increased

processor speeds required to handle large video files

Multimedia Applications

• Training: Cheaper alternative to traditional techniques for staff induction, training in new procedures and general management training

• Architectural Visualisations: CAD system

• Advertising/promotions Logos, trademarks, and storyboard outlining: Advertising can be created, animated, and given a sound track using multimedia authoring software

• Home Entertainment: include interactive cartoons, games, and an interactive multimedia world atlas


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E-MAILAdvantages• Quick inexpensive

immediate contact can be made

• Using the cc or bcc facility numerous communications can be distributed simultaneously

• Attachment facility provides the means of forwarding long files

Disadvantages• Carries of viruses

• Unsolicited e-mails: Spam


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Viruses• A virus is a program code written to replicate

by attaching copies of itself to other objects within the system, normally also having a detrimental effect. Usually lie dormant for a while, then establish their presence by displaying a message, stopping the computer or deleting a file.

• These destructive programs infect a computer similar to the way biological viruses infect people.

• Problems may range from displaying messages through loss of service to corruption or complete destruction of data

• A program virus will seek out and copy itself into other program files whenever a previously infected program is run.


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Virus Protection

• To protect, purchase your software only from reputable dealers

• Run an anti-virus utility and back up hard drive• Greatest carriers of viruses are disks which are illegally

copied programs, especially games

Backup

• A copy you make of a file in case the original file gets destroyed or corrupted

• Use backup command of your computer

• Can back up files to floppy disks, a tape drive etc


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Precautions and power failure

• Use special anti-power surge extension leads on all computer sockets

• Use UPS (Un-interruptible Power Supply)• Have backup of files

macalvey/teachnet/bits& bytes 2005 1 bits and bytes! concepts of ict explained

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