Understanding Computer Systems: Software, Hardware, and Control Devices, Summaries of Business Economics

Download Understanding Computer Systems: Software, Hardware, and Control Devices and more Summaries Business Economics in PDF only on Docsity!

lOMoARcPSD|

T. Jackson,

Information techonology

INFORMATION AND

COMMUNICATION

TECHNOLOGY

CIE – IGCSE

Winter 2013

TYPES AND COMPONENTS OF

COMPUTER SYSTEMS

Hardware

• Tangible physical components of a computer system.
• You can feel it or touch it
• E.g. Monitor, printer, processor

Software

• Programs that control computer systems
• Set of instructions that make the computer system do something
• You cannot physically touch software
• Relates to ideas and instructions for using physical objects
• Two types of softwares: System Software
• Programs that allow the hardware to run properly
• Control computer's hardware and application program
• Communicate with user
• E.g. Operating system Application software
• Programs that allow the user to do specific task
• Design to carry out tasks
• Can be general purpose software or custom made software (specialist software)
• E.g. Spread sheets, databases, word processing Zubair Junjunia

Basic computer model Backing store

• Stores data/information and programs not being used at current time
• Backing store device = reader or recorder e.g. Hard disk drive
• Backing store media = hardware containing data e.g. Hard disk CPU
• Processing done by central processing unit
• Three main components o Control unit - coordinates input and output devices and carries out program instructions o Arithmetic and Logical Unit (ALU) - performs calculations and logical comparison: A < B? o Immediate access store (IAS) - holds data and program instruction in current use Main components of computer systems
• Input devices: keyboard, mouse
• Output devices: monitor, printer
• Secondary storage devices: DVD R/W drive, removable hard drive
• Process and internal memory devices: Central Processing Unit (CPU), internal hard disk, random access memory (RAM), read only memory (ROM) Microprocessor
• Used instead of CPU
• Single integrated circuit Zubair Junjunia

GUI - Graphical User Interface

• Uses graphics to stand for the complicated actions
• Use icons
• Use a mouse to selector the icons
• Screen divided into windows allowing different things on each
• WIMP - Windows Icons Menus Pointers
• Requires little IT knowledge Advantages
• Easy to use
• Easy to explore and find your way around the system
• Do not have to learn complicated commands
• Exchange data between different softwares
• Good help facilities provided with GUIs Disadvantages
• Larger amount of hard disk space than other interfaces
• Significantly more memory (RAM) to run than other interface type
• GUI use more processing power than other types of interfaces
• GUI can be slow for experienced programmers to use, they find CLI much faster CLI - Command Line Interface
• Types commands to tell the computer what to do o The user must know all the commands o Must not make typing errors
• Used by technicians
• Can access everything on the computer system
• GUI users can only access places they have icons for Advantages
• Knowing the correct commands, this can be much faster than any other interface type
• Uses much less memory (RAM) than any other interface type
• Low resolution, cheap monitors can be used
• CLI does not require Windows to run Disadvantages
• Can be confusing
• Commands have to be typed precisely, if there is a spelling error the command will fail
• If you mistype an instruction, it is often necessary to start all over again
• Large number of commands need to be learned

Types of Computers PC/Desktop Computers

• Refers to general purpose computers
• PC refers to IBM compatible computers, distinguishing them from the Macs
• Made up of separate monitor, keyboard, mouse and processing unit Advantages
• Spare parts standardized results in low costs
• Tend to have better specifications
• Large casing allows good dissipation of heat build up Disadvantages
• Not portable since they are not made up of separate components
• Wiring clutters up desk space
• Necessary to copy files as they aren't portable Laptop (Notebook)
• Refers to computers where monitor, keyboard, pointing device and processor together in a single unit.
• Extremely portable systems o Low weight o Low power consumption
• Processor doesn't generate too much heat Advantages
• Portable because monitor, pointing device, keyboard, processor and backing store units are together in one box.
• No trailing wires
• Full advantage of Wi-Fi
• Can link into any multimedia system Disadvantages
• Easy to steal
• Limited battery; need to carry charger
• Keyboard and pointing device awkward to use
• Heat dissipation is difficult due to laptop structure

Main frame computers

• Large, very powerful computer systems
• Purpose is to run commercial applications
• Several CPUs
• Very fast processor speed
• Support multiple operating systems
• Huge amount of storage capacities
• Huge internal memories (RAM)
• Often operate using time sharing or batch processing Advantages
• Can do very large due to feature listed above
• Used in time sharing systems
• Capable of very large number crunching Disadvantages
• Needs to be permanently housed in a large room
• Very expensive to maintain and operate

INFORMATION AND COMMUNICATION TECHNOLOGY Zubair Junjunia

Numeric Keypads

• A numeric keypad is used to enter numbers only
• Although some have function key to allow input of alphabetical characters Uses
• Used in Automatic teller machines (ATMs), where customers can key in their personal identification number (PIN), or an amount of money
• Used to key in phone numbers into telephones
• Electronic point of sale (EPOS) terminals have numeric keypads in case the barcode reader fails
• Used in Chip and PIN devices to key in PIN, or amount of money
• Used to enable fast entry of numeric data into a spread sheet Advantages
• Numeric keypads are faster than standard keyboards for entry of numeric data
• Since many are small devices (e.g. mobile phones), they are easy to carry around Disadvantages
• Can be difficult to use due to the very small keys
• Difficult to use for entering text
• Sometimes the order of the numbers isn’t very intuitive Mice
• An example of a pointing device
• The ball underneath the mouse is used to detect movement
• The left button is for selecting by double on it and the right is to bring drop-down menus
• There is usually a scroll button which speeds up the process of moving through a document Uses
• Used for opening, closing and minimising software
• Used for grouping, moving and deleting files
• Useful when editing images (e.g. controlling the size and position of the image)
• Used for controlling the position of a pointer on the screen to allow: o Selection from a menu o Selecting an icon o Scrolling up/down and right/left

Advantages

• Faster to select an option by a mouse than a keyboard
• Enables rapid navigation through applications and the internet
• Mice are small and don’t take much area Disadvantages
• People with restricted hand/wrist movement can find it hard to operate a mouse
• Easily damaged and can easily be clogged up with dirt
• They are hard to use if there is no flat surface available Touchpads
• Touchpads are used in many laptop computers as a pointing device
• The pointer is controlled by the user moving their finger on the touchpad Uses
• Used for opening, closing and minimising software
• Used for grouping, moving and deleting files
• Useful when editing images (e.g. controlling the size and position of the image)
• Used for controlling the position of a pointer on the screen to allow: o Selection from a menu o Selecting an icon Advantages
• Faster to select an option by a touchpad than a keyboard
• Enables rapid navigation through applications and the internet
• Since the touchpad is integrated into the laptop computer, there is no separate mouse, aiding portability
• They can be used when no flat surfaces are available Disadvantage
• People with limited hand/wrist movement can find touchpads hard to use
• It can be more difficult to control the pointer when compared to a mouse
• They are more difficult when doing operations such as ‘drag and drop’

Joysticks

• By gripping the stick, a pointer on the screen can be controlled
• Buttons are used to make selections Uses
• Video/computer games are often controlled by joysticks
• They are used in simulators to mimic actual controls Advantages
• Easier to navigate round a screen compared to a keyboard
• Control is in three dimension Disadvantages
• More difficult to control the on-screen pointer with a joystick than with other devices such as mice Touchscreens
• User can choose an option by simply touching a button/icon on the screen
• The selection is automatically made without the need for any pointing device Use
• Used for service tills e.g. petrol stations
• Used where selections are made on a screen e.g. ATMs, public information systems, airports and railway stations
• Used in PDA’s
• Used in Interactive white boards
• Used in computer based training (CBT) Advantages
• Enable faster entry of options than a keyboard or a mouse
• Very easy to choose options
• User friendly method for inputting data
• They are tamperproof, preventing people from keying in information (which could corrupt the system) Disadvantages
• There is a limited number of options available
• Using touchscreens often can lead to health problems e.g. (straining of arm muscles and RSI)
• The screen can get very dirty with constant touching

Magnetic Stripe readers

• Used to read information on the magnetic stripe
• The stripe contain useful information such as start and expiry date Uses
• Credit and debit cards have magnetic stripes that are used by ATMS or EFTPOS (electronic funds transfer point of sale) terminal
• Security cards for entering building e.g. hotel rooms
• Travel systems e.g. train and underground tickets Advantages
• Data entry is fast compared with keying in using a keyboard or keypad
• System is error free, no typing involved
• Information is secure since there is no typing and the information can’t be read directly by a person
• Can prevent access to restricted/secure areas
• Magnetic stripes are unaffected by oil water and moisture
• No moving parts therefore physically robust Disadvantages
• If the magnetic stripe is damaged the data is lost
• Card needs to be in close contact with the reader
• Since the information is not human readable, they need to find a way to show the information to the customer (e.g. hotel room number not printed on cards) Smart Card readers
• Contain chips
• Data is stored on a chip and can be updated
• Chip has a larger storage capacity than a magnetic stripe Uses
• Loyalty cards, ID cards and public transport passes
• Can be used to track customer/passenger movement
• Used with a satellite system to decode program signals
• Used for electronic passports and driving licences Advantages
• Some smart cards are used instead of money
• The chip on the card does not need to be in contact with the reader
• Data is more secure since it’s easier to copy data of magnetic stripe than on a chip

Barcode readers

• Used to read information in the form of a barcode
• Handheld scanners or wands are very common for reading barcodes Uses
• Used in supermarkets and other shops where the goods are marked with a barcode
• Used in libraries to scan users library card and barcodes on books (in order to keep track of books on loan)
• Used as a safety function in many companies to ensure that electrical equipment is checked on a regular basis Advantages
• Faster than keying in information, and fewer mistakes are made
• Used as a way of recording data, can improve safety
• Barcodes enable automatic stock control
• Barcode scanning is a tried and trusted technology
• When an item price is changed, only the central database needs to be updated, there is no need to change the prices individually on each item Disadvantages
• Barcode scanning is an expensive system to administer since every item in the shops needs a barcode and every barcode needs to be entered on the system. Also there is a need to invest in the computer technology together with staff training, which can all be expensive
• The system is not fool proof- barcode can be swapped around on items OMR Devices
• Optical mark recognition is a system which can read marks written in pen or pencil Uses
• OMR devices are used to read questionnaires, multiple choice examinations papers and other types of forms in the form of lines or shaded areas Advantages
• A very fast way of inputting results of a survey
• Since there is no typing, it is more accurate than keying in data
• OMR is more accurate than OCR

Disadvantages

• Forms need to be carefully designed to make sure that the marks/shadings are correctly positioned to gather accurate information
• There can be problems if forms aren’t filled correctly, sometimes they have to be checked manually before being read by an OMR, this is both time consuming and expensive OCR readers
• Optical Character recognition is a software that takes scanned text and converts it into a computer readable form Uses
• Processing of passports and Identity cards
• OCR is used when scanning documents to modify them using a suitable software Advantages
• Much faster data entry system than manually keying in data
• Since there is no manual data entry, the number of errors is reduced Disadvantages
• The system has difficulty reading handwriting
• It is still not a very accurate technique MICR Device
• Magnetic ink character recognition is a system which can read characters printed in a special ink Uses
• Used to process cheques in banking operations – cheque is read using a batch processing method Advantages
• MICR offers great security than OCR since the oriented characters cannot be altered
• There is no manual input, thus errors are reduced
• If somebody writes over the magnetic ink characters it can still be read Disadvantages
• Only certain characters can be read and the number of different characters is very limited
• It is a more expensive method than other methods used for direct data entry