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ICT Theory by Mind Map: ICT Theory
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ICT Theory

4. Computer networks

Types of networks

LAN, Local Area Network, Usually within one building, Consist of:, Computers, Printers, Hubs/Switches, Router-> WAN (??), Advantages, Sharing of resource (hardware & software), Communication within network, Easy to monitor all users, Disadvantages, Easy spread of virus, Printer queues, Slower access to external networks, Sercurity risk withing networks, Reliance of server

WLAN, Wireless LAN, Like LAN but with no cables, Consist of:, Access points cnt. wire networks, Similar to LAN, Advantages, No Cable, Save money, Better safety, More flexible, Easy to add new devices, Other advantages of LAN's, Disadvantages, Sercurity is more difficult, Problems with interference, Data transfer rate is slower than LAN

WAN, Wide Area Network, LANs connected through modem/router, Consist of, routers/modems, proxy servers, Advantages, Private, for companies, Enhanced security, Disadvantages, Expensive, ISP more commonly used

WiFi, Any system where possible to connect to network/single computer through wireless communications, WiFi hotspots, where you can access WiFi (free/paid), Public Spaces, Cafes, Hotels, Airports, Trademark name for any product based on the IEEE 802.11 standard, Rely on form of AP which uses radio frequency tech to enable a device to send and receive signals

Bluetooth, example of WPAN (wireless personal area networking), Possible to create mini-LAN at home, connecting mobile phones, computers, media-players and printers, Use to send files from phone to computer, or phone to phone

Network Devices

Network Hubs, Hardware device, Connected to a number of computer/devices, Takes data from one port and distribute to all ports connected

Switches, Like a hub but it controls which port the data goes through- therefore more efficent

Bridges, Connect one LAN to another, Decides whether a message heading towards the other LAN or within its own LAN

Routers, Connect LANs together and connect them to the internet

Proxy Servers, A buffer between a LAN and a WAN (usually the internet), Websites information are stored on the server, So another user accessing the webpage can do so efficiently

Internet and Intranet

Internet, Global WAN, INTERnational NETwork., Huge Collection of networks which allows subscribers to, Chat, Listen to streamed music, Watch streamed video, Send and Receive emails, Share Files, World Wide Web, accessed through web browsers, IE, Firefox, Chrome, Use URLs (Uniform Resource Locations), protocol://siteadress/path/filename, Made up of millions of websites and web pages, Web pages have multimedia, Hyperlinks allow users to navigate between web pages, Internet access through ISP (internet service provider), Dial up, Slowest, connect via telephone line ; dial special number from ISP, Limited hours per month; extra charges if exceeded, Ties up the telephone line when in use, Cable, Local cable TV give access using their own cable networks using a "cable network modem", DSL (digital subscriber line), FATTEST! zoooom, good for VOIP, Often offered with wireless interface which needs AP and router, ISP often have download/upload limit, Always on, doesn't tie up telephone line, Can be accessed from anywhere provided user has ISP account

Intranet, INTernal Restircted Access NETwork, network based on internet tech designed to meet internal needs for sharing info within company, Requires password entry and can only be accessed from agreed points, Advantages, Safer, less chance of hacking/virus, Prevent access to unwatered websites, Can ensure info available is specific to needs, Easier to send out sensitive messages, Remain Only within company

Network Security

User ID, Assigns different level of authority to different users

Passwords, Something only authorised personnel should know, Should be difficult to guess

Encryption, Converting data into a code- scrambling or encoding it, Only user with decryption key can unscamble, Does not prevent hacking- only makes data useless to hackers

Authentication, Something you know- PIN, Something belonging to you- credit card, Something unique to you- fingerprints

Communication Methods

Fax, Documents scanned electronically and converted into bit map image, The series of electrical signal is transfer over the telephone network, Receiving fax machine transfer into image and print on paper, Less efficient than email

Email, Pros, Fast speed, Low cost, Multimedia files can be sent, Cons, Possibility of virus threat

Video Conferencing, Uses LAN or a WAN, Additional hardware required- webcam, microphones, etc, Pro:, Real time, Saves money in traveling cost, Saves time in travelling, Meetings can be organised at short notice, Con:, Due to time difference it can be difficult to organise a meeting, Less human/society/personal contact, Time lag could cause problems, Initial cost in hardware and software

VOIP, Free or at local rate to anywhere in the world, Con: Vulnerable to security issues

5. Data Types

Data types

Logical/Booleans, Yes/No data, E.g. Paid?

Alphanumeric/text, Text data, E.g. Name

Numeric, Number data; statistics, E.g. Age

Date, Date formated data, E.g. D.O.B.

Data structures

Files, Contains number of records

Files

Records, Contains fields

Fields, Contains data

Databases

Relational database, Consist of various linked tables, Contain primary keys/foreign key that links all tables

Flat-file database, Contains only one table of data

Analogue/Digital

Analogue, An analogue signal is one which has a value that varies smoothly, i.e. sound, temperature

Digital, Digital data are all represented by numbers

ADC, Analogue Digital Convertion, Computers can only understand digital data, If you want to attach an analogue input device to a digital device such as a computer, you will need an analogue to digital convertor (ADC).

3. Storage Devices and Media

Backing up data

Types of access

Serial Access, Starts at beginning and access each piece of data until the required info. is found, Primarily used on magnetic tapes, Slow form of access, Used when speed is not important, Updated by merging two tapes, Examples:

Direct Access, Used with magnetic disks and optical disks, Access the data directly from position, Much faster than serial access, Used when speed is vital, New information is added to next available location

Backing storage media

Magnetic, Fixed hard disk, Used to store operating system and working data, Also stores application software, Found on all computers, Advantages, Very fast data transfer rate, Very large memory capacity, Disadvantages, Easy to be damaged, Lack portability, Portable hard disk drive, Same as fixed disk except connect by USB, Capable of storing more than optical media, Used to transfer data and for back-up, Advantages, Fast transfer rate, Large memory capacity, Portable, Disadvantages, Easy to damage, Floppy disk drives, Still used to transfer small documents, Used by older computer systems, Advantages, Cheap, Less wasteful than CDs, Disadvantages, Very low memory capacity, New computers don't have floppy disk drives, Slow in data transfer, Not very robust, Magnetic tape, Used as back-up media, Used in batch processing i.e. cheques, bills, pay slips, Advantages:, Generally less expensive, Very robust, Transfer rate is fast, Disadvantages:, Access time is slow, Hard to update

Optical, CD-ROM/DVD-ROM, ROM- Read Only Memory: Cannot be rewritten, CD-ROM used to store music, softwares, games, etc., DVD-ROM used to store films, Advantages:, Holds more than floppy disks, Less expensive than hard disks, Disadvantages:, Data transfer rate and access time are slower than hard disk drives., CD-R/DVD-R, R stands for recordable: write on it only once and it becomes a ROM disk, Used for home records of music/films, Stores data for later use, Advantages:, Cheaper than RW disks, Once burned acts like a ROM disk, Disadvantages:, Can only be recorded on once, Not all players read R disks, CD-RW/DVD-RW, Advantages, Can be reused many times, Less wasteful than R-disks, Disadvantages, Can be relatively expensive, Data can be accidentally overwritten, DVD-RAM, Can be read and written at the same time, Used in camcorders to store film, Advantages:, Long useful life, Possible to re-write over 100.000 times, Reliable, Access is fast, Large capacity, Can read and write at the same time, Disadvantages:, Not as compatible, Relatively expensive, Blu-ray disks, Used to store home videos, Can be used to backup hard disk, Camcorders can use this media, Advantages:, Very large capacity (100GB), Fast data transfer rate, Fast access rate, Disadvantages:, Relatively expensive, Has/had problems with encryption

Solid state, Memory stick, Used for transferring files and for back-up, Advantages:, Compact + Robust, Portable, Disadvantage:, Data and files cannot be protected, Easy to lose, Flask memory card, EEPROM, Electrically Erasable Programmable Read-Only Memory, Devices that use:, Cameras, MP3, Mobile phones, Advantages:, Compact, Robust, Disadvantages, Relatively expensive per GB of memory, Generally lower capacity

6. Effects of using ICT

Software copyright

Certain rules must be obeyed when given software on discs

Illegal to make copies then sell

Should not be used in multiple computers unless licensed to do so

Illegal to copy code for own use

Illegal to rent without permission

Illegal to use name of software on another

Viruses/Hacking

Virus, A program that duplicates itself- design to cause harm to a computer system, Corruption of files, Loss of data, Causes computer to crash, Solutions:, Use up to date anti virus software, Do not download illegal data/software, Use firewalls

Hacking, Gaining access to a network/computer without legal authorisation, Use firewalls, Use user ID plus a robust password

Society

Employment, Advantages, Fewer manual taks, Creates new job opportunities i.e. web designer., Safer working environments, De-skilling workforce (No need professional model maker, computer can do), Consistency, Machines do not take holidays, etc, Less labour cost, Disadvantages, Unemployment- workers getting replaced, Causes unemployment in labour and manufacturing fields

Online shopping and banking, Advantages, No need to travel, Have access to wider market, Disabled/elderly people can stay home, Available 24/7, Saves time, Saves money, Disadvantages, Lack of socialisation, Security issues i.e. hacking, virus, Not possible to see goods first- quality control, Risk of lack of exercise, Closure of highstreet shops and banks, Effects on companies, Save cost, Wider costumer base, New cost in re-training staff

Policed?, Arguments for:, Prevents illegal material from being posted i.e. racist, prejudiced, pornographic, terrorism promoting materials, Some information on the web (i.e. how to make a bomb) could lead to dire consequences., Prevent children's exposure to undesirable websites, Reduce amount of inaccurate info being shared, Arguments against:, Some materials published on websites can be found in other medias anyways, Expensive to implement- who pays?, Difficult to implement, Against freedom of information, Some laws are already in existence to stop certain material from being on the web

Information from the internet

Reliability?, More up to date, Faster to get information, Could be inaccurate, bias, Hard to finds exactly what one needs

Undesirability

Security issues, Phishing, Sends victim to fake website where they type in personal information, Pharming, When victim enters website on their own accord, pharming sends them to a fake website instead. Harder to realise you're a victim., Spam, Spyware, Gathers user information through recording key strokes and cookies

Internet Development

Blog

Wikis

Digital media sharing websites, YouTube, Flickr, Photobucket

Social networks, Facebook, Twitter, Google+,

Health and Safety

Health, Back and neck strain, Adjustable chairs, Foot rest, Tilt-able screen, Repetitive strain injury, Ensure posture is correct, Use a wrist rest, Take breaks/ do exercise, Use ergonomic keyboard, Eyestrain, Take breaks, Use anti-flare screen, Headaches, Anti-glare screen, Take breaks, Ozone irritation, Ensure proper ventilation, Use a different type of printer

Safety, Electrocution, Check insulation of wires regularly, Do not allow drinks near computers, Check equipment regularly, Trip Hazard, Use cable ducts, Cover wires/tuck them away, Use wireless connection when ever possible, Heavy equipment, Use strong desk, Use larger desk/table, Fire risk, Have a CO2 fire extingusher, Don't cover equipment vents, Maintain hardwares, Ensure good ventilation in the room, Don't overload sockets

7. Applications of ICT In Real Life

Communication

Multimedia Presentions, Advantages, Include different media, Can be interactive

Paper-based presentations, No special effects, Extra cost of printing, Some form of distribution needed, A copy can be kept and access whenever

Flyers and posters, DESKTOP PUBLISHING, Need to know the process- How do you make posters? :O

Websites, Advantages:, Add different medias, Link to other websites, Interactive, Disadvantages:, Can be hacked into, Need a computer and a internet connection to access, Need to maintain the wbepage

Music, Music samplers/mixers, Electronic instruments, Synthesisers, Music scoring

Animation

Satellite/ mobile network connections

Mobile phone network (3G)

Embedded Web Technology, To be able to control devices across the internet, E.g. turn off the oven at home from your office

Global Positioning Satellite (GPS) system, On-board computers in cars store maps, Location of car is determined and shows up on map, Advantages:, Safer due to the lack of need of paper maps, Remove errors in traveling, Warns driver about speeding cameras, Estimate time of arrival, Disadvantages:, If maps are not up to date- errors, If road is temp. closed- errors, Loss of satellite reception- errors, Incorrect start or end point entered- errors

Data handeling

Surveys, Using OCR or OMR (Please check that up in chapter 2), Faster, Less errors, Less manpower needed- less money

Tuck shop records, Use of spreadsheets

Clubs and society records, Using database

Record keeping, See Chap 8

Simulations

Using spreadsheet to estimate how much a shop can make in theory

Simulate how a device might work using simulation softwares

Processing

Batch Processing, When all the "jobs" are collected and processed all at once, Payroll P.g. 86, Billing system P.g. 86, Bank Cheque Processing: Cheques are gathered altogether after some specified period and read and recorded by MICR., Advantages: no user interaction needed once process starts, Disadvantage: Can only be done where there are no time constrains.

Real-time transaction processing, Used for flight booking, cinema booking, and at ATMs, Used when time is crucial

Real-time process control, Like real-time processing but for analogue datas

Control and monitoring

Turtle graphics

Application using sensors (pg 82)

Stock control system

Barcodes are used in:, Library, Administration systems, Passport/ ID card systems, Equipment checking system

Each barcode is attach to an item

Each barcode is attached to a file contain all details for an item

When costumer brings product to EPOS- barcode is scaned

Price is displayed back to costumer

Stock of item is decreased by 1

When stock gets too low, the system automatically orders a new batch from the supplier.

Banking

ATMs, Disadvantages:, 'Fake' ATMs can be found, Charges are sometimes added, PINs can be seen as stolen

Electronic Fund Transfer (pg 90), Flowchart

Library

Book files, Barcode, Book Title, Author, Date published, due date, ISBN

Borrower's files, Borrower's name, Borrower's number, Barcode of books borrowed

Expert systems

Uses, Medical diagnosis, Situation diagnosis, Mineral Prospecting, Chess game

Features, Knowledge base, This is a collection of facts and rules. The knowledge base is created from information provided by human experts, Inference engine, This acts rather like a search engine, examining the knowledge base for information that matches the user's query, Rule base, A series of inference rule used by inference engine to draw conclusions

How to set up, Interview experts, Knowledge base designed then created, Rules base designed then created, User interface designed and created, System tested against known senarios, Check to see if match original specifications

Advantages, Provide consistent answers, Reduces time needed to solve a problem, Less workforce required- saves money, Allows access to expertise in areas otherwise not available to.

Disadvantages, Tend to lack common sense, If there are errors in knowledge base, inaccurate decisions could be made, Can to expensive to set up initially, Operators need to be trained for correct usage of system

8. System Analysis and Design

Analysis

1. Fact-finding from current system, Observation, watch personnel use existing system to find out exactly how it works (STALK THEM), Advantages, first hand, reliable data, Relatively inexpensive, Disadvantages, People uncomfortable and may work differently if they know they're watched, Questionnaires, Advantages, Questions can be quickly answered, Relatively inexpensive, Anonymity possible, Allows quick data analysis, Quick and simple= Good for large groups!, Disadvantages, Often hardly anyone answers them/do it seriously, Generic questions inflexible, limited, No immediate way to clarify weird answers, Interviews, Advantages, Interviewee more motivated to give open honest answers, Analyst can probe for more feedback, extend/modify questions, More detailed information, Ideal to explore a specific aspect of existing system, Disadvantages, Time Consuming, Time=Money, Expensive, You cannot be anonymous., looking at existing Paperwork, Advantages, Get info unaqquirable thru other methods, See big picture: scale of problem, type and quantity of data in system, required memory size + devices etc., Disadvantages, Time consuming, Time=Money, Expensive

" Feasibility Study", 2. Establish description of current system (its inputs, outputs and processing), 3.Identify problems of current system, 4. Agree objectives with customer, 5. Identify user+customer needs, 6. Interpret customer needs, 7. Produce cost-benefit analysis, 8. Produce data flow diagram, More about the study, Aims to see if it is possible to devise a system that can be implemented and that will work at a reasonable cost., Results of the study are presented as a feasibility report concluding whether or not the proposed initial design should proceed.

Design

Validation routes, Validation: Asking "Is the data valid?" - to ensure input data MAKES SENSE, Different validation checks for different fields, Range check (Everyone should be 0 - 150 years old), Length check (DOB must have 6 digits), Character/data type check (only digits are allowed in the DOB field!), Format check (DOB ought to be in dd/mm/yy form), Limit check (like range check except just one limit, e.g. Nobody should be >150 years old), Presence check (Error: you have forgotten to input your email address), Check digit ( An extra digit calculated from the code and then added to the end of code, in order to check accuracy of other characters in the code)

Verification methods, Prevents errors when data is copied (e.g. from paper to disk) and to check input data is CORRECT., Double Entry, Data is entered twice (preferabbly by two different ppl...), Computer compares the entries (either after/during entry), Computer identifies any differences (if there are, Error message appears to make someone correct the error), E.g. when you make a new password, Visual comparison, Person checks for errors by comparing entered data (on screen) with original data (on document/paper), NOT proof reading

Data capture/input forms, Must be Well designed, Have all necessary fields (e.g. DOB), Suitable controls for each field (textboxes the right size, buttons, tickboxes/radio-buttons, drop-down menus), Clear Instructions (if needed), Spreads out neatly across screen area available (good layout)

Other things designed/decided, Screen layouts + displays, Reports/output forms, Data/file structures, Software and Hardware requirements, System flowcharts/psuedo-code, Testing strategy/Plan

Development/testing

It involves.., Testing individual modules to see if they function on their own and then test All Modules Working Together (the whole system), There may be data clashes, incompability and memory issues etc when all modules are put together, Inputting normal data to see if desired outcomes can be produced., Input erroneous/abnormal data to see if validation procedures identify the errors., Input large quantities of data into the system to test system can cope, Input extreme data to check validation procedures can cope.

Why?, To ensure system is robust and functional, Save costs later on, make system worth implementing (which takes much time + money)

What if there is failure?, Modifications to design will need to be made, then we go back to testing., user interface, systems flowchart, file structures, input methods or output formats may be amended, NOT hardware/software

Data types, Abnormal, Data that does not fall within the set boundaries for acceptable data. Remember to give an example relevant to the question!, Normal, Data within the set boundaries for acceptable data and has an expected outcome., Extreme, Data at the.absolute limits of the normal range. Extreme data IS Normal data!, Live, Data that is actually part of the customer's business / organisation

Implementation

Some Tasks Involved, Transfer paper/electronic files to new system, Scan in documents, Key in data, Download files to new database, Install software, hardware, Train staff for new system

The Four Methods!, Direct changeover, Old sytem stopped overnight, new system introduced immediately. Wachau!, Suitable for small systems, Advantages, Quick, Benefits immediate, Reduced costs, no need to pay for Two Systems, Disadvantages, High Risk:, Method can be disastrous if new system Fails (no back-up system), Parallel running, Old and New system run side by side for a time b4 new system takes over, Suitable for systems where there are doubts about the new system, All of the data that is input into the old system is also input into the new one., Advantages, Old system is available as back-up, Possible to train staff gradually, Staff have time to familiarise with new system, Disadvantages, More expensive as extra staff needed to run Two Systems together, Phased implementation, The new system is introduced in phases gradually replacing parts of the old system until eventually the new system has taken over., Suitable for large systems, Advantages, Possible to ensure system works properly before expanding, Disadvantages, More time and effort than Direct - need to evaluate each phase before moving on, Pilot running, New system started in one part of company (e.g. an office/department) to assess performance. If successful, the rest of the company switches to the new system., Like parallel running at a small scale, Advantages, Only part of company affected should new system fail, Costs less than parallel, Need to train staff in one area only, Disadvantages, There is no back-up system for the office / department doing the pilot., Remember to apply the concept to the situation proposed in the Question (e.g. hospital, library), Pg 100 of textbook is quite helpful for comparison of the methods

Documentation

User, designed to help users learn how to use the software or system, how to log in/log out, how to save files, how to input/output data, trouble-shooting guide, FAQ

Technical, designed to help programmers and analysts who need to make improvements to / maintain / repair the system, program coding, system flowcharts, validation rules, file structures

Similarities!, purpose of system, limitations of system, hardware and software requirements

Evaluation

Is the sytem..., Efficient?, Easy to use?, An Appropriate Solution?

Strategies, Compare final solution with original task requirements, Identify limititations and necessary improvements to the system, Evaluate the user's responses to the results of testing the system, How is feedback gathered?, Questionnaires, Interviews, Observations

If there is strong evidence suggesting changes need to be made this can ultimately lead back to a re-design of part of the system.

1. Types & Components of Computer Systems

Hardware/Software

Hardware: physical components of a computing system

Software: programs that control the computing system, System Software: Allows hardware to run properly. E.g. operating system, Application software: Allow the user to do specific tasks

Main components

Input devices

Output devices

Secondary storage devices

Processor&internal memory devices, CPU, Central Processing Unit, Interprets and executes commands, AKA microprocessor, Hard disk, Where application software, operating system and data files are stored., Further discussed in Chap 3, RAM, Random Access Memeory, Internal chip, Application data temp. stored, Contents are lost when comp. turns off, AKA Volatile memory, ROM, Read Only Memory, Stores permanent information e.g. config. data, Cannot be altered. Stayed after comp. turns off., AKA Non-volatile memory, Also contains boot files- BIOS. CMOS stores date and time and is battery powered.

Operating systems

General Tasks, Control operation of hardware, Supervise operation of software, Deal with errors, Maintain security, Maintain computer log, Allow communication

CLIs, Command Line Interfaces, Requires user to type in instructions, Allows direct communication between user and computer., Hard to learn, Slow to carry out

GUIs, Graphical User Interface, Users interact with computer using pictures or symbols, WIMP- Windows Icons Menu and Pointing device

Types of computers

PC/Desktop, Advantages, Low cost due to standardised parts, Better specs (Faster processors), Good dissipation of heat built-up, Disadvantages, Not portable, Wiring needed for diff. components- takes space

Laptops, Advantages, Portable, No wires-everything is in one unit, WiFi compatible (Full Advantage), Disadvantages, Easy to steal, Battery life, Keyboard and touchpad can be hard to use, Heat dissipation is difficult

Netbooks, Smaller version of laptops, Advantages, Same as laptop, Disadvantages, Same as laptop, Lack of optical drive, Small keyboards

PDAs, Advantages, Can be used everywhere, Lightweight, Disadvantages, Difficult to enter text quickly, Lack of certain features

Mainframe, Advatages, Can have several CPUs, Very fast processing speed, Supports multiple operating systems, Large storage capacity, Large RAM, Capable of dealing with complex mathematical functions., Disadvantages, Large hence difficult to house., Expensive to operate and maintain.

2. Input and Output Devices

Input Devices

Keyboard, Alphanumeric data input, commands(e.g. PrntScr), Advantages, Fast entry, Well tried, well known, Easy to use, Easy for visual comparison, as text appears on screen simultaneously, Disadvantages, Hard to use for users with limited arm/wrist use, Slow compared to direct data entry (eg OMR), Large, use valuable desk space

Numeric keypad, Numerical data input - ATMS-PINs, Telephones + Mobile Phones, EPOS

Pointing devices, Mouse, Optical, Cordless, Need flat surface!, Touch pad, Trackerball, may need training to use, not standard equipment

Remote control, allow operation of equipment from a distance

Joystick, control is in Three Dimensions!

Touch Screen, can get pretty dirty

Scanners, Non-digital photographs, books, documents can now become digital :)

Cameras, Digital cameras, no need for film developing any more!, Video Cameras, Web Cam, Allow more personal online chatting

Microphones, involves usage of ADC

Graphics tablet, Input of freehand drawings, use in CAD

"Readers", Magnetic stripe readers, Read Info From Magnetic Stripe : Credit Card, Security Cards, Underground Tickets, Account number, Sort Code, Expiry Date, Start Date, Advtg, Faster than keyboards, Error free, no typing involved, Secure, Stripe cannot be read by human eye, No risk of someone observing your key strokes, No moving parts, Robust, Stripe unaffected by oil, water, moisture, Dis-advtg, Stripe damaged (by overuse, strong magnetic field) = data gone, Readers do not work at a distance, Smat Cad reader, Smart Cards, ID cards, loyalty cards, credit cards, CARDS.., Advtg, Store more data than stripes, More Secure: Harder to copy information on a chip, No required physical contact between chip and reader, so causes less damage, Info on Chip may be Updated, Disadvtg, Info on chip could be used in identity theft if card is lost, Chip and PIN readr, EFTPOS terminals = restaurants, cashier counters in shops, PIN typed in must match up with PIN stored on chip, more secure than signature and magnetic stripe, Gotta be careful when typing in PIN, OMR, Optical Mark Reader : input pencil/pen marks from school register/exam answers/questionnaires etc, Advtg, Quick and Accurate, more accurate than OCR!, Dis-advtg, Forms need careful design + positioning and need to be filled in correctly, OCR, Optical Character Recognition : converts scanned text into computer readable form., Advgt, Faster than keying in data, Dis-Advtg, has difficulty reading handwriting, Not a very accurate technique, MICR, Magnetic ink character recognition : can read characters printed in special ink with iron and then convert them into computer readable form, Primarily used in banking ops ~ cheques, Advtg, Greater security than OCR, Printed Characters Cannot be Altered, No manual input, less errors, Magnetic ink characters can still be read despite markings (e.g. signature) over it, Dis-advg, More expensive than other direct data entry methods, Number of different characters is limited, Barcode readers, Found at POS Terminals, Hoorah! No need to change prices invidually on each item when an item price is changed = only central database needs to be updated, Expensive - gotta get barcodes, gotta stick em, gotta train staff, gotta get computers, gotta input barcodes

Light Pen

Sensors

Sensors are devices with input data to a computer

Temperature, Washing machines, Central heating systems, Greenhouses, Ovens

Pressure, Burglar alarm system, Washing machine, Environmental monitoring, Robotics

Light, Greenhouses, Automatic doors, Burglar alarm, Street lighting systems

SCIENTIFIC EXPERIMENTS

Control Devices

Motor, Washing machines, Fans (Cooker), Water pump (Central heating system), Open windows (Greenhouse), Operate robot arms, Operate disk drives

Buzzers, Cookers and ovens, Burglar alarm system

Lights, Security lights, Green house

Heaters, Washing machines, Cookers, Central heating systems, Greenhouse

Output Devices

Monitors, CRT : Cathode Ray Tube, Advg, Least expensive monitor, Has wider angle of viewing, Produce higher quality image, Work with light pens!, Dis Advg, Take up more space, Can Get quite Hot - Potential fire hazard if left unattended, Potential weight hazard, Consume more power, Health hazard, flickers, TFT : Thin Film Transistor, Advg, Lightweight, Less Glare, Less Radiation, Consume less power, Dis Advg, See advantages of CRT., Laptops!

Multimeida Projector, presentations

Printers, Laser, Pros, Fast for high volumes, Handles large print jobs well, High consistent quality, Toner cartridges lasts for long, Cons, Expensive to buy, Only fast when large quantity is being printed, Colour laser printers are expensive to run, Produce OZONE!!!! x_x, Uses, High quality, high quantity output is needed, Low noise is needed, Inkjet, Pros, High Quality, Cheaper than laser, Smaller than laser, Do not produce ozone :D, Cons, Slow for large jobs, little buffer capacity to store pages, Large jobs = ink cartridge run out too quickly, Printing can smudge, Expensive--> original ink cartrides Expensive, Uses, Small print jobs, Home Use, Dot Matrix, Pros, Can be used in undesirable environments, Carbon prints can be produced, Cheap to run and maintain, Easy to use when requiring continuous stationery, Cons, Very noisy, Cost more than inkjet, Slow and poor quality printing, Uses, Used in noisy environments, When quality is not important, Graph Plotter, Pros, HUGE printouts possible, Very high print Quality *, Cons, Slow in operation, EXPENsive - to buy and maintain, Uses, CAD applications: Produce large drawings e.g. blueprints of buildings, Produce large pics for billboards, Possibly make large signs (replace pens with blades)

Speakers