CCEA ICT Revision

AS level ccea ICT exam. Specification to be changed for 2016The This is my last futile attemp to revise for this exam so sit back, relax, assume the foetal position and get ready for my shitstorm of knowledge extrava-fucking-ganzaI do not own or take...

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1.2)

Students should be able to:

describe the features of batch processing and real time transaction processing;

Batch Processing

Data transactions are grouped into convient sets.

The complete batch is processed at a set time

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1.2) Systems Software-

Students should be able to:

describe the features of operating systems: single user, multitasking and multi-user;

Features of an OS

To provide an interface between the human and the computer.

To share the computers external resources between the users such as peripherals.

To allocate internal resources such as memory/ processor time/ memory management.

To control hardware input devices and output devices.

To prioritise system requests/ interrupts.

To overcome the speed mismatch between computers and humans.

To control/ share software e.g. multitasking, multi-user 

Single User

System that is designed to be used by one person at a time.

The OS is responsible for interacting with one user and will load and run one program at a time.

Examples including PalmOS

Multi-tasking

Allows the user to perform more than one task at a time i.e. run more than one application at a time.

Example: have a browser and word processing SW open at the same time.

The OS must keep track of where the user is in these tasks and enable them to go from one to the other without losing data.

The OS allocated storage and other resources accordingly.

Each task may have its own window.

Each task can be totally independent of each other.

The tasks can be dependent e.g. they may share data.

The OS allocated storage and other resources accordingly.

In preemptive multitasking, the OS allocates CPU time slices to each program/ task.

In cooperatively multitasking, each program has the use of the CPU for as long as it needs.

Multi-User

Enables many users to run programs simultaneously from a few users up to 1000′s of users.

The OS must make sure that the resources allocated to the current users are balanced so that each user has sufficient and resources wile the overall performance of the system is satisfactory.

Time slicing can be used.

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1.2)Control unit, RAM, ROM & Cache

Students should be able to:

describe the purpose of the main CPU components: control unit, arithmetic and logic unit and internal memory (ROM, RAM, cache);

Internal Memory

ROM- Read Only Memory: To permanently store the boot up sequence/ bootstrap/ OS core/ BIOS.

RAM- Random Access Memory: To store data currently in use. To store the current application.

Cache Memory: To store the most recently/ frequently accessed data.

Control Unit

 To direct the flow/ sends a series of commands.

The flow of program instructions including jumps/ loops and data in and out of memory and in and out of registers.

Fetches and decodes instructions.

Arithmetic & Logic Unit

To perform calculations such as addition/ subtraction/ division/ multiplication.

To perform Boolean/ AND/ OR operations/ comparisons/ decisions.

To perform shift operations.

ROM

To store the BIOS/ Kernel of the OS permanently/ so that it is always available for bootstrapping/ booting up.

The bootstrap/ core/ minimum set of operating is held in ROM.

This cannot be erased/ it is permanent.

It is available as soon as the computer is switched on.

It is available all the time the computer is switched on.

RAM

This is temporary/ volatile storage.

It holds programs while they are being executed and data while it is being directly processed/ upon input/ prior to being stored in external memory.

The rest of the operating system/ the most commonly used part of the operating system is held in RAM.

The memory can be changed.

This part of the OS is loaded by the bootstrap.

RAM is cleared when the computer is switched off.

Cache

To allow the processor to operate at full speed by storing data in faster memory (SRAM)

The cache holds data that the processor is likely to use in the very near future.

Used by a proxy server to store recently downloaded Web Pages.

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1.2) Storage Devices

Students should be able to: compare common optical and magnetic storage devices in terms of storage capacity, cost, speed of access and retrieval: – hard disk, DVD, CD-RW, CD-ROM, CD-R, tape streamer, pen drive, Blu ray, HD DVD;

Tape

Data stored as magnetic fluctuations.

Coded data processed into information for computer, very slow.

Holds 1000′s MB and used for daily backups of work and programs on network- Tape Streamers- scheduled to make backups at night.

Floppy Disk

Magnetic storage device.

Faster than tape.

Needs to be formatted in tracks and segments to organise where data is stored.

Holds 1.44 MB

Uses: transferring work & backing up.

Easily damaged + cheap.

Formatting  a hard/ Floppy disk

Is to wipe all the information on the storage medium.

Zip Drive

Magnetic storage device.

High capacity storage.

Larger and thicker than floppy.

Stores 250 MB

Transferring large files.

Hard disk

Magnetic storage device.

Made of aluminium inside of the computer permanently

faster than 1 MB per second.

Holds gigabytes of data.

USES: Storing programs & files for fast access.

capacity: 40 GB - 160 GB +

Compact Disk (CD-ROM)

Optical

Stored by laser technology, can be read not written to.

ROM, faster than floppy but slower than hard drive.

Holds up to 650 MB

USES: Large programs, information libraries, music, safest form of storage.

CD-R

Optical

Compact Disk Recordables

One time recording (worm) can hold up to 74-80 min of data (650-700 MB)

CD-RW

Compact Disk Rewriteable

Repeated recording.

Holds 74-80 minutes of data (650-700 MB)

Works with a CD-RW drive.

Digital Versatile Disk (DVD)

Optical large capacity

stores up to 17 GB, 4.2 GB DVD drive can also read CD-ROM.

A laser beam is used to read the data.

On a read-only DVD, pits are pressed into the surface.

These are detected by the change in the intensity of the reflected laser beam.

On a DVD-R or DVR+R, the laser burns/ heats the dye on the surface of the DVD changing its reflectivity.

On a non-rewriteable DVD, the writing laser is more powerful than the reading laser.

Optical Disk

Looks and used like a floppy but has a CD inside.

can read and write to disk repeatedly.

Has 100 MB capacity.

Bar Code

Parallel black lines which represent decimal number code.

Computer prints them and can be scanned very quickly.

Data Logger

Remote input/ output devices.

Stores data received from sensors.

Can be inputted different time or place.

USB

Universal Serial Bus

Memory stick with magnetic storage.

Capacity: 64 MB, 128 MB, 2565 MB, 512 MB, 1 GB +

Blu-Ray

Advantage:

The format was developed for high definition video (HD) and for storing large amounts of data permitting high definition audio and video/ providing clearer pictures with improved colour and vividness.

Disadvantage:

Blu-Ray is a new/ emerging technology and players and discs are still relatively expensive, the range of films is restricted.

HD-DVD

Advantage:

Increases in capacity, with particular benefits in improving the resolution of recorded films or in games.

Disadvantage:

Discontinued to the rival of Blu-Ray.

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1.2) Speech input, output & actuators

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Speech Input

A microphone attached to a soundcard is used to capture speech.

The signal is converted from analogue to digital using sampling.

The digital signal is compared to a database of sounds for a matching pattern of frequencies/ wavelengths.

Advantages:

No special ICT skills required, just spoken commands.

The user can control the system from a distance.

Can be designed only to respond to certain peoples voices.

Can be adapted for remote activation e.g. by phone.

More suitable for people with disabilities.

Disadvantages:

Can be complicated/ time consuming to calibrate/ set up.

Could be actiavted by extraneous sounds e.g. background noise.

May fail to respond to user if they have a cold for example.

May respond to a word not intended as a command.

Sound Output

PC needs a soundcard to convert digital sound data into analogue electrical signals.

Speech synthesis software can be used to convert text into speech. Such a system contains a database of words and their sounds, which are retrieved when a word is spoken.

Actuators

An actuator is often part of a computer control system.

The actuator is a mechanical device or motor which carries out the action or decision made by the control system.

For example, in a greenhouse, sensors may measure the temperature. When the temperature rises too much, the control system will send a signal to open the windows or vents.

The actuator is the motor which will open the vents. Likewise, when the temperature drops, the control system will send a message to the actuator (motor) to close the vents.

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1.2) Printers

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Printers

connected to computer transferring information from computer to printer.

Can be Impact/ Non-Impact, Character line/ page Printers.

Hardware needed: USB cable/ Serial cable.

Software needed: Setup/ Installation CD (Driver).

DPI: Dots Per Inch, Number of dots that make up an inch of a printed image, higher the DPI, sharper the image.

Draft Mode: Faster, uses less ink, less wear on ink heads.

PPM: Pages Per Minute, measures speed of the printer by how many pages it can print.

Memory Buffer: part of printer RAM, processors can output data faster than can be acceptred so stores data waiting to be printed.

Print Server: A computer that holds files and documents waiting to be printed, used in networks.

Impact: creates marks on page by striking ink ribbon against it, making noise.

Non-Impact: No contact with paper, no noise.

Daisy Wheel Printer

Like typewriter but has letters on ends of spokes to form a wheel.

Letters strike ribbon onto paper.

Very slow (1/2 PPM)

Noisy, no graphics

One colour (Impact)

Dot Matrix printer

Print head made up of steel pins strike an inked ribbon producing a sequence of dots.

quite fast (1 PPM)

Print any shape of character and graphics (Impact)

Ink-Jet Printer

Fires a jet of liquid ink through tiny nozzles onto page.

Fast.

Very quiet.

Print black and colour on same page (non impact).

Laser Printer

Non-impact

like photocopier, Powered ink fused onto paper by heat and pressure.

Very fast (12 PPM)

Almost silent (non-impact)

Braille Printer

Converts text into braille code.

Producing patterns of raised dots.

Plotter

Is an impact printer.

Used to create architect plans.

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Big Tough Creampuff

Dude on 24 hours in A&E

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1.2) Data Projectors, Monitors (LCD, CRT & TFT)

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Data projectors

An output device- displays the output from the computer to which it is connected.

Projects the output onto a screen.

Projects a high quality image.

Can be controlled via a remote control focus/ image size can be changed.

Monitors- (LCD,CRT & TFT)

Resolution can be measured in pixels.

LCD

Liquid Crystal Display

Smaller/ lighter/ less power than monitor/ found in laptops/ watches/ calculators/ LCD projectors.

CRT

Cathode Ray Tubes

Provides 3 electron guns located at the rear of the monitor, one of each of the primary colours.

The inside of the screen is coated with tiny red, green & blue phosphorous dots.

Guns are directed at the dots.

TFT

Thin Film Transistors

Improved over earlier generations of LCDs

Resolution-

Quality of the image of the screen.

Based on the number of pixels.

More pixels, the sharper the image.

Pixel-

Smallest area of a VDU that can be edited.

VGA (Video Graphics Array), SVGA (Super Video Graphics Array), XGA (Extended Graphics Array)

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1.2) Input Devices- Scanner, Temperature Sensor & Interactive White Board

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Scanner

Scans page;

Transmits image to the computer as a digital image.

Images can be saved, printed and changed.

Resolution- DPI (Dots Per Inch), OCR (Optical Character Recognition)

Temperature Sensor

It consists of a thermocouple.

It contains 2 sensors.

One at a reference temperature the other at the temperature to be measured.

the temperature difference causes a voltage to change.

the voltage is sampled at regualr intervals and converted from analogue to digital.

Interactive White Board

An output device- displays the output from the computer to which it is connected (via a data projector)

An input device- the user can select GUI options using a special pen.

Handwritten notes can be written on the screen and saved for later use (in image form) or printed out for distribution in class.

The handwritten notes can be converted to text using OCR.

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1.2) Input Devices- Barcodes, ATM, MICR & Barcode reader

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Barcodes

The bar code consists of a pattern of lines/ stripes/ black and white lines of varying thickness.

A laser beam is reflected off the pattern to give a digital representation which uniquely identifies the object containing the barcode.

ATM

Automated Teller Machine

Input:

The cash card is inserted.

The PIN is entered.

A menu choice is selected.

An amount is entered or selected.

Processing:

The customers data is retrieved from the banks database.

The PIN is validated.

The amount is checked against the customers balance.

The amount is then deducted from the customers balance.

Storage:

Customer data is stored in the cash card.

customers details are stored in the banks database.

Details of the transaction are stored in the banks database.

Output:

Instructions/ menu choices are displayed on the ATM screen.

A receipt may be printed.

A sum of money is issued.

the card is ejected.

Feedback:

The amount is immediately deducted from the customers balance so that the balance is always up to date/ the customer cannot withdraw an unauthorised amount.

If an error or exceptional conditions occur/ the card is invalid/ the PIN is incorrect/ the withdrawal amount is not possible, an error message appears on the ATM screen to which the user must respond.

MICR

Magnetic Ink Character Recognition.

Characters, written in a special font, are told apart through their magnetic fields- used exclusively in the Banking Industry.

It uses special magnetised ink.

It has the advantage of being fast and minimises human errors- hard to forge cheques as the special magnetic ink is difficult to reproduce accurately.

Bar Code Reader

reads information in bar code form.

used to read the prices of items at checkout.

Items found on a supermarket bar code are- Product Code, Country of origin, Manufacture, Check digit.

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1.2) Input Devices- Touch Screens, OCR & OMR

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Touch Screen:

Touch Sensitive Screen

User touches icon,

Infrared light detects finger position.

Advantages:

Don’t need a mouse/ keyboard.

Easy to use.

No training needed.

Cannot steal components.

Easy to reprogram if changes need to be made.

Graphics Tablet

Consists of a flat surface containig a touch-sensitive membrane which detects the location of a specially designed stylus.

As stylus is moved across thew pad, movement is interpreted by software such as drawing, which appears on the computer screen.

Each point on tablet represents the same fixed point on the screen, in contrast to the position of the mouse.

OCR

Optical Character Recognition

A printed document is scanned on a flatbed scanner.

The image is captured using light/ a laser beam.

Special software can interpret or convert letters as ASCII (American Standard Code for Information Interchange) text which can then be processed as standard word processed text.

Most document formatting is not recognised.

OMR

Optical Mark Recognition

A special document/ form is used to collect the data.

This has specific areas/ boxes representing the users choices/ answers/ selections which the user shades in/ fills in perhaps using a specific grade of pencil/ using a HB pencil.

The document is scanned using light.

The reflected light is analysed and the positions of the users answer/ choices determined against a template.

Benefits- Human error is eliminated and the answers can be read at electronic speeds reducing the processing time.

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1.2) Input Devices- keyboards and pointing devices.

Students should be able to: evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Keyboards:

Have keys which when pressed send digital code to the computer which gives computers commands.

4 groups of keys on QWERTY keyboard are:

Numeric

Function

Cursor

Alphabetic

Concept keyboard

Overlays on keyboard with text or pictures.

Keys sensitive aresa of a plastic surface.

Easy to operate.

Use in a restaurant.

Advantages:

Fast input of data

can be wiped clean.

Limited choices so less chance of making mistakes.

Mouse

Has a rotating ball.

Movement detected by sensors.

hand used to move mouse on flat surface making cursor correspond.

When a button is pressed it sends signal to the computer.

Trackerball

Like an upside down mouse, stays still, the user moves the ball and is used on laptop computers.

Touch Sensitive Pad (Tracker Pad)

The screen is an input and output device.

The screen is covered by a membrane/ a line of infrared sensors/ along the edges of the screen which is sensitive to pressure.

The pressure of the users finger is detected.

The finger cuts the beam and an X and Y position is calculated.

Joystick

As the stick is moved forwards/ backwards/ left/ right the movement is detected by sensors/ switches which detect the X and Y coordinates of the stick.

A sensor detects the depression of the button.

the signals from the sensors are input to the computer.

AD (Analogue-->Digital) conversion may be used.

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1.2) Input devices

Students should be able to:  evaluate a range of input and output devices:  keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;

Printers.

Connected to computer transferring information from computer to printer.

Can be Impact/ Non impact/ Character line/ Page Printers.

Hardware needed: USB cable/ Serial cable.

Software needed: Setup/ Installation CD (Driver)

DPI: Dots Per Inch, Number of dots that make up an inch of a printed image, higher the DPI, sharper the image.

Draft Mode: Faster/ uses less ink/ less wear on ink heads.

PPM: Pages Per Minute, Measures speed of the printer by how many page it can print.

Memory Buffer: Part of printer RAM, processors can output data faster that can be accepted so stores data waiting to be printed.

Print Server: A computer that holds files and documents waiting to be printed, used in networks.

Impact: Creates marks on page by striking ink ribbon against it, making noise.

Non-Impact: No contact with paper, no noise.

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1.4) Disaster Recovery Plan.

Students should be able to:

describe the main features of a disaster recovery plan.

It describes how critical operations will be restored after a natural or human-induced disaster including plans for coping with the unexpected  or sudden loss of communications and key personnel and backup and recovery procedures.

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1.4) Measures to protect the information systems

Students should be able to:

explain the measures that can be taken to protect information systems from misuse;

Install anti-virus software.

Install a firewall.

Use a proxy server.

Remove/ disable scan portable devices such as memory pens.

Introduce an acceptable use policy. new point.

Train users to avoid opening suspicious emails etc.

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1.4) Types of viruses (worm, macro & logic bomb)

Students should be able to:

compare various types of viruses: worm, macro and logic bomb.

Types of Viruses

Worm

A malicious program which replicates itself from system to system without the use of a host file.

Worms generally exist inside of other files.

A worm will pass on a file infected with a malicious macro using more and more of the computers memory.

Macro

A macro is a way to automate a task or procedure which you perform on a regular basis.

A macro is a series of instructions and/ or actions that can be recorded and then set to run whenever you need to perform the task in the future.

Is usually attached to a document or spreadsheet and uses the macro functions/ language of the application.

It is typically designed to run automatically when a document/ spreadsheet is opened.

It copies itself and spreads from one file/ document/ spreadsheet to another by infecting the applications start up file.

Logic Bomb

A logic bomb lies dormant until a specific piece of program code is activated.

A typical activator for a logic bomb is a date, the logic bomb checks the system date and does nothing until a pre-programmed data and time is reached.

A logic bomb may wait for a certain message from its programmer before executing its code.

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1.4) Viruses

Students should be able to: 

explain what is meant by a virus;

Students should be able to:

Viruses

A program or programming code that replicates itself by being copied or initiating its copying to another program.

Some viruses can cause damage to the computer system or to data as soon as their code is executed; other viruses lie dormant until circumstances cause their code to be executed by the computer.

Viruses can be harmful, erasing data or causing your hard disk to require reformatting.