Cambridge International Examinations AS ICT (9626) Theory Workbook September 2021 Student Name:
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Cambridge International Examinations
AS ICT (9626)
Theory Workbook
September 2021
Student Name:
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Contents
Topic 1: Data, information, knowledge and processing ............................................ 4
1.1 Data, information and knowledge ..................................................................................................................... 4
1.2 Sources of data .................................................................................................................................................. 4
1.3 Quality of information ....................................................................................................................................... 10
1.4 Coding, encoding and encrypting data........................................................................................................... 11
1.5 Checking the accuracy of data ....................................................................................................................... 24
Topic 2: Hardware and software ........................................................................ 26
2.1 Hardware ........................................................................................................................................................... 26
2.2 System, application and user interface software ........................................................................................... 33
2.3 Utility software .................................................................................................................................................. 50
2.4 Custom written software and off-the-shelf software ...................................................................................... 52
2.5 Compiler and interpreter .................................................................................................................................. 53
Topic 3: Monitoring and control ........................................................................ 56
Topic 4: E-safety and health and safety .............................................................. 60
Topic 5 : The digital divide .............................................................................. 67
Topic 6: Using networks................................................................................... 69
6.1 Network types ................................................................................................................................................... 69
6.2 Video and web conferencing .................................................................................................................................. 78
Topic 7: Expert systems ................................................................................... 84
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Topic 1: Data, information, knowledge and processing
Week 1 – Lesson 1
1.1 Data, information and knowledge
• define data, clearly identifying that data has no meaning
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• define information and show how data can become information through context and meaning
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• define knowledge and Explain that information becomes knowledge when human experience is applied
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Exam Practice Questions
Specimen - 2017
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1.2 Sources of data
1) Define static data and give an example
Static Information Sources - Advantages Static Information Sources - Disadvantages
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2) Define dynamic data and give an example
Dynamic Information Sources - Advantages Dynamic Information Sources - Disadvantages
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3) Define direct data source and explain the advantages and disadvantages of gathering data from direct data
sources
Direct Information Sources - Advantages Direct Information Sources - Disadvantages
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4) Define indirect data source and explain the advantages and disadvantages of gathering data from indirect data
sources
Indirect Information Sources - Advantages Indirect Information Sources - Disadvantages
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1.3 Quality of information
• Explain how the following can affect the quality of information:
• Accuracy
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• Relevance
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• Age
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• level of detail and completeness of the information
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1.4 Coding, encoding and encrypting data
• describe the coding of data (including: M for male, F for female) and more intricate codes (including: clothing type,
sizes and colour of garment)
Give examples of coded data:
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• discuss the advantages and disadvantages of the coding of data
Coding Data - Advantages Coding Data - Disadvantages
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• evaluate the need for encoding data
It is common for much of the data collected and entered into a system to have some degree of repetition and
redundancy i.e. extra information that does not add anything.
And this pattern or repetition is why it is efficient to code the data in some way.
Need 1: Speeding up data entry
Let's take the example of collecting data about a person's gender. People can be either 'Male' or 'Female'.
Whilst these two options are easily understood by all, imagine having to enter the word 'Male' and 'Female' into a
system many hundreds of times. It is a waste of time and effort because no extra information is contained in the full
words compared to a single letter.
Need 2: Increase accuracy of data entry
The other issue is that no matter how accurate a person is at data entry, at some stage they are likely to make a
mistake and might spell 'Male' as 'Mail' or 'Female' as 'Femal'. This type of mistake will make any results from your
database queries unreliable.
Instead of entering 'Male' or 'Female' you could code the data and instead enter it as 'M' or 'F'.
Simply having to enter one letter instead of a possible six will speed up data entry. It will also cut down on the risk
of mistakes being made with spelling.
Need 3: Use of validation
In our example, the words 'Male' or 'Female' have been coded so that they become 'M' or 'F'.
When data has been coded it makes it easier to use validation to check if the data entered is sensible. With the
example above, the person entering the data could still make a mistake and enter 'S' instead of 'M' or 'F'.
But if you set up validation so that the field will only accept the letters 'M' or 'F' and absolutely nothing else then
that should further cut down on possible mistakes.
Note that validation can only check if the data is sensible and within reasonable limits, it cannot check whether the
data is accurate. Somebody could still enter 'F' instead of 'M'.
Need 4: Less storage space required
Every letter that you store in your database system will take at least one byte of storage. If you store 'Female' as 'F'
then you will save five bytes of storage space. If the system belongs to a large organisation, there might be many
thousands or millions of records stored - simply by coding one field, a huge amount of hard disk storage can be
saved.
Need 5: Faster searching for data
It stands to reason that the smaller the size of your database, the faster it will be to search and produce results.
Thus by coding data and keeping the size of the system to a minimum the more time you can save in the long run
when running queries.
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Analyse the different methods that can be used to encode data (including: codecs)
• Analogue to Digital convertor
• Codecs
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Exam Questions Practice
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• define encryption and describe different methods of encryption (including: symmetric, asymmetric, public key, private
key)
Data Encryption:
• Symmetric Key Encryption (plain text, cypher text and use of a key)
• Asymmetric Key Encryption (plain text, cypher text and use of a private and public key)
• Cipher Encryption (Substitution and reposition)
Encryption is the process of converting information into a form that is meaningless to anyone except holders of a ‘key’.
What is plain text?
In cryptography, plaintext is ordinary readable text before being encrypted into ciphertext or after being decrypted
About Cyphers
There are many types of ciphers developed over time.
Most common ciphers involved some form or substitution or transposition of alphabetical letters. Substitution means to
substitute one character for another while transposition is some form of repositioning characters within the message (which
literally scrambles the information).
In the digital age, ciphers changed and are generally based on two types of algorithms--one using the same key to encrypt and
decrypt (symmetric encryption), and one using different keys to encrypt and decrypt (asymmetric encryption). The one that uses
symmetric keys falls under private-key cryptography, while asymmetric key algorithms falls under public-key cryptography.
Example of symmetric encryption also known as private-key cryptography
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First Alice needs to generate a secret ‘key’ using encryption software. The key is usually a very long, random number.
Alice must then give a copy of this key to Bob. She must make sure that nobody else can get to the key. (So maybe Alice will visit Bob and give him a copy of the key on a memory stick or floppy disc).
Now that Bob has a copy of the key, each time Alice needs to send him a message she starts by encrypting it using special encryption software and the secret key.
The encrypted message now looks like a jumble of random letters and numbers. Alice then sends the encrypted message to Bob.
She can use a public network like the Internet, since, even if it gets stolen, the encrypted message cannot be read or understood without the key.
When Bob receives the message, he uses special decryption software and his copy of the secret key to decrypt the message.
Bob can now read the original message from Alice.
Advantages
a) Data is scrambled into unreadable form/only person/computer with key can understand data b) increasing the length of a key increases the strength of the encryption
Disadvantages:
a) It is slower than normal browsing. It takes a while for the browser to do the maths required to scramble the message and another delay on the server that has to unscramble the data.
b) The recipient may lose the private key.
c) It can be a complicated business running a secure server, so very often, ordinary online shops will hire a specialist 'Payment Gateway' such as 'WorldPay' or 'Paypal' to handle payments for them.
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Symmetric Encryption
Symmetric encryption is the oldest and best-known technique. A secret key, which can be a number, a word, or just a string of
random letters, is applied to the text of a message to change the content in a particular way. This might be as simple as shifting
each letter by a number of places in the alphabet. As long as both sender and recipient know the secret key, they can encrypt
and decrypt all messages that use this key.
Asymmetric encryption also known as Public-key cryptography
Public-key cryptography, also known as asymmetric cryptography, is a class of cryptographic algorithms which require two
separate keys, one of which is secret (or private) and one of which is public.
Asymmetric Encryption
The problem with secret keys is exchanging them over the Internet or a large network while preventing them from falling into
the wrong hands. Anyone who knows the secret key can decrypt the message. One answer is asymmetric encryption, in which
there are two related keys--a key pair. A public key is made freely available to anyone who might want to send you a message. A
second, private key is kept secret, so that only you know it.
Any message (text, binary files, or documents) that are encrypted by using the public key can only be decrypted by applying the
same algorithm, but by using the matching private key. Any message that is encrypted by using the private key can only be
decrypted by using the matching public key.
This means that you do not have to worry about passing public keys over the Internet (the keys are supposed to be public). A
problem with asymmetric encryption, however, is that it is slower than symmetric encryption. It requires far more processing
power to both encrypt and decrypt the content of the message.
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Explain how encryption can be used to protect data:
• On a hard disk
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• In e-mail
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• On HTTPS websites
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Exam Questions Practice
• discuss encryption protocols (including: the purpose of Secure Socket Layer (SSL)/Transport Layer Security (TLS)
and the use of SSL/TLS in client server communication)
Secure Socket Layer (SSL) and Certificates
SSL stands for Secure Sockets Layer. It provides a secure connection between internet browsers and websites, allowing you to transmit private data online. Sites secured with SSL display a padlock in the browsers URL .
What is SSL used for?
The SSL protocol is used by millions of e-Business providers to protect their customers, ensuring their online transactions remain confidential. A web page should use encryption expected to submit confidential data, including credit card details, passwords or any personal information. All web browsers have the ability to interact with secured sites so long as the site's certificate is from a recognized certificate authority.
SSL exists for two reasons:
• Encryption Hiding what is sent from one computer to another. The data is scrambled up so that it becomes meaningless to someone without the key to decrypt it.
• Identification Making sure that the computer you speaking to is the one you trust
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Encryption Protects Data during Transmission
Web servers and web browsers rely on the Secure Sockets Layer (SSL) protocol to help users protect their data during transfer by creating a uniquely encrypted channel for private communications over the public Internet. Each SSL Certificate consists of a key pair as well as verified identification information. When a web browser (or client) points to a secured website, the server shares the public key with the client to establish an encryption method and a unique session key. The client confirms that it recognizes and trusts the issuer of the SSL Certificate. This process is known as the "SSL handshake" and it begins a secure session that protects message privacy, message integrity, and server security.
How does SSL work?
1. A browser attempts to connect to a website secured with SSL. 2. The browser requests that the web server identify itself. 3. The server sends the browser a copy of its SSL Certificate. 4. The browser checks the certificate root against a list of trusted Certificate Authorities and that the certificate
is unexpired, unrevoked, and that its common name is valid for the website that it is connecting to. 5. The server sends back a digitally signed acknowledgement to start an SSL encrypted session. 6. Encrypted data is shared between the browser and the server and https appears.
What is an SSL Certificate?
SSL Certificates are small data files that digitally bind a cryptographic key to an organization’s details. When installed on a web server, it activates the padlock and the https protocol and allows secure connections from a web server to a browser. Typically, SSL is used to secure credit card transactions, data transfer and logins, and more recently is becoming the norm when securing browsing of social media sites. SSL Certificates bind together:
• A domain name, server name or hostname.
• An organizational identity (i.e. company name) and location.
An organization needs to install the SSL Certificate onto its web server to initiate secure sessions with browsers. Depending on the type of SSL Certificate applied for, the organization will need to go through differing levels of vetting. Once installed, it is possible to connect to the website over https://www.domain.com, as this tells the server to establish a secure connection with the browser. Once a secure connection is established, all web traffic between the web server and the web browser will be secure. Browsers tell visitors a website is SSL secure via several visible trust indicators:
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To view the details of an SSL Certificate, go to a secure site, click on the padlock and select “View Certificate”. All browsers are slightly different, but the Certificate always contains the same information.
SSL Certificate Details
To view the actual contents of the Certificate click the "Details" tab:
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Detailed steps on how SSL works:
https://www.youtube.com/watch?v=iQsKdtjwtYI
• What are the two main purposes of SSL?
• Which applications use SSL?
• What is a SSL certificate and what does it contain?
• How does SSL work? Draw a block diagram to represent the steps
Questions:
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• What is the purpose of TLS?
• What are the two main layers that make up a TLS?
• How is TLS different to SSL?
TLS (Transport Layer Security)
Questions:
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1.5 Checking the accuracy of data
• Define validation
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Description Example
presence check
range check
type check
length check
format check
check digit
lookup check
consistency check
limit check
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• define verification
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Analyse verification methods (including: visual checking and double data entry)
• Visual Checking
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• Double Entry
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• explain the need for both validation and verification
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Topic 2: Hardware and software
2.1 Hardware
• Define the term hardware
Computer hardware is the collection of physical elements that constitutes a computer system. Computer hardware is
the physical parts or components of a computer, such as the monitor, mouse, keyboard, computer data storage, hard
disk drive (HDD), graphic cards, sound cards, memory, motherboard, and so on, all of which are physical objects that
are tangible. In contrast, software is instructions that can be stored and run by hardware.
• Evaluate internal hardware devices (including: central processing unit (CPU), motherboard, random access memory
(RAM), read only memory (ROM), graphics card, sound card, hard disk drive (HDD), solid state drive (SSD))
INTERNAL HARDWARE What does it do?
Central processing unit
Main internal memory
(RAM)
Other internal memory
(ROM)
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Motherboard
Graphics cards
Sound cards
Hard Disk Drive
Solid State Drives
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• evaluate external hardware devices (including: cloud, monitor, keyboard, mouse, printer (laser, inkjet, dot matrix,
plotter), speakers, camera (digital, video), web cam, scanner, magnetic ink character reader (MICR), optical mark reader
(OMR), optical character reader (OCR), bar code reader, pen drive, portable hard disk drive, blue-ray disk drive,
memory card)
EXTERNAL HARDWARE
Cloud
Monitor
Keyboard
Mouse
Laser Printer
Inkjet
Dot matrix
Plotter
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Speakers
Camera (digital, video)
Web cam
Scanner
Magnetic ink character
reader (MICR)
Optical mark reader
(OMR)
Optical character
reader (OCR)
Bar code reader
Pen drive
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Portable hard disk drive
Blue-ray disk drive
Memory card
In the exam you will expected to:
*Explain the purpose of input and output devices
*Evaluate different input, storage or output devices for a given task
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• Explain the purpose of storage devices
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• Evaluate storage devices (including: magnetic tape drive, optical, hard disk drive (HDD), solid state drive (SSD))
What is it? Advantages Disadvantages
Magnetic
tape drive
Optical
Drives
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What is it? Advantages Disadvantages
Hard disk
drive (HDD)
Solid state
drive (SSD)
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Software Type 2: ……………………………………………………….
Linux
MAC Windows
Software Type 1: …………………………………………………………………
Software can be described as ……………
Operating system/systems software is ……………….
2.2 System, application and user interface software
•
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Exam Questions Practice
Specimen - 2017
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• explain the purpose of system software (including: compilers, linkers, device drivers, operating systems and utilities,
interpreters)
An operating system controls the operation of the computer system by managing the computer's memory, processes,
and all of its software and hardware. Without the operating system the computer will not work. Describe the following
features of systems software:
Device
drivers
Utilities
Compilers
Interpreters
Linkers
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• evaluate application software (including: word processing, spreadsheet, database management systems, control
software, measuring software, applets and apps, photo editing software, video editing software, graphics manipulation
software, communications software, web authoring software)
Word processing
Spreadsheet
Database management systems
Control software
Measuring software
Applets and apps
Photo editing software
Video editing software
Graphics manipulation software
Communications software
Web authoring software
*evaluate application software for a given task
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W
I
M
P
Characteristics :
• evaluate the characteristics of different types of user interface (including: command line interface, graphical user
interface, dialogue interface, gesture based interface)
Graphical User Interface (GUI)
Windows
Other GUI operating systems:
A Command Line Interface (CLI)
Windows Command Prompt
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Characteristics:
Characteristics:
Dialogue Interface
Gesture Based Interface
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Advantages Disadvantages
Gra
phic
al u
ser
inte
rfac
e
Com
man
d lin
e int
erf
ace
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Advantages Disadvantages D
ialo
gue I
nterf
ace
Gest
ure b
ased I
nterf
ace
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Exam Questions Practice
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• evaluate the use of colour, layout, font size, quantity of information and controls when designing a user interface
Why is it important in user interface design?
Colour
Font size
Layout
Quantity
of
information
Controls
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• evaluate mental models and how they can be used when designing a user interface
A mental model is an explanation of someone's thought process about how something works in the real world.
• Mental models include what a person thinks is true, not necessarily what is actually true.
• Mental models are similar in structure to the thing or concept they represent.
• Mental models allow a person to predict the results of his actions.
• Mental models are simpler than the thing or concept they represent. They include only enough information to
allow accurate predictions.
We can portray mental models using several key parts:
1. An image (needed if the mental model is of a physical thing). If the mental model is of a physical object, the
model should contain a simplified image that serves as a template for that object
2. A script (needed if the mental model has a process). If the mental model is of a process, it should contain
some sort of description of that process. The best way to present the script will vary—it might be a series of
steps expressed verbally, a flowchart, or a decision tree.
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2.3 Utility software
• Define utility software
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• Describe the role of different utility software (including: anti-virus, back-up, data compression, disk defragmentation,
formatting, file-copying, and deleting)
Utility Software What does it do?
Anti-virus
Back-up
Data compression
Disk defragmentation
Formatting
File-copying, and
deleting
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2.4 Custom written software and off-the-shelf software
• compare the benefits and drawbacks of custom written software and off-the-shelf software
Cust
om
w
ritt
en so
ftw
are
Advantages Disadvantages
Off
-the-s
helf
so
ftw
are
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2.5 Compiler and interpreter
• describe the function of a compiler and an interpreter
The programmer will choose to use a certain computer language with which to write code. For example they may
favour the language C++ or they may choose Python. In either case the programmer writes a series of statements to
form his computer program.
These statements are called 'source code'.
The purpose of a 'compiler' is to translate source code into machine code.
The code a compiler generates is stored as an 'executable file'. Another name for an executable file is the 'object
file', (not a generally popular term but your exam question may mention it). When this file is run, the machine code
commands that it contains begin to be processed by the CPU.
A compiler produces fast, efficient code that are stored as an executable file. Once the compiler has done its job,
you can pack it away. Just run the 'exe' file.
So why are there different ways of doing things? Why bother with interpreters?
An interpreter will translate each line of source code into machine language and then execute that machine code
directly.
An example of this is entering instructions on a BASIC interpreter command line.
Advantages of interpreters
1. Debugging
Imagine you are busy programmer and you want to make sure that each line of the source code you are typing in, is error free.
As we have mentioned, simple typos will trip you up, miss a comma, semi colon, bracket in the grammar of the high level language and you wiill see a long, de-moralising, list of errors to be fixed in your source code (many of which are spurious, adding to the hassle!). What if a program could check each line of code as you generate it.
This is one important role of interpreters, it makes debugging simpler as it immediately checks your source code.
2. Less memory
Another advantage is memory. It uses less memory than an exectuable file because only a few lines of source code needs to be in memory at any one time.
3. Less prone to crashing
Some interpreters execute code within a 'virtual machine'. For example the Flash Player and the Java Virtual machine. These have been designed to dis-allow code from directly accessing the computer. So you may crash the virtual machine with faulty code, but most likely the host computer will still be running just fine.
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Disadvantages of interpreters
The biggest disadvantage is speed. Interpreted code runs slower than compiled code.
This is because the interpreter has to analyse and convert each line of source code (or bytecode) into machine code before it can be executed.
Evaluate the difference between a compiler and an interpreter
Compiler Interpreter
Fast, creates executable file that runs directly on the CPU Slower, interprets code one line at a time
Debugging is more difficult. One error can produce many
spurious errors
Debugging is easier. Each line of code is analysed and checked before being executed
More likely to crash the computer. The machine code is
running directly on the CPU
Less likely to crash as the instructions are being carried out either on the interpreters' command line or within a virtual machine
environment which is protecting the computer from being directly accessed by the code.
Easier to protect Intellectual Property as the machine code is difficult to understand
Weaker Intellectual property as the source code (or bytecode) has to be available at run time. For example if you write a Flash
Actionscript application, you can easily get de-compilers that convert the p-code back into actionscript source code (unless you
use encryption, but that is another story).
Uses more memory - all the execution code needs to be loaded into memory, although tricks like Dynamic Link
Libraries lessen this problem
Uses less memory, source code only has to be present one line at a time in memory
Unauthorised modification to the code more difficult. The executable is in the form of machine code. So it is difficult to
understand program flow.
Easier to modify as the instructions are at a high level and so the program flow is easier to understand and modify.
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Exam Questions Practice
Specimen - 2017
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Moisture Temperature
Gas
Pressure
Sound
Light
Humidity
PH
Infra-red
Magnetic field
Topic 3: Monitoring and control
Candidates should be able to:
• identify a range of sensors and describe their use in monitoring technologies
Sensor How it works
Produces a signal that depends on the concentration of water vapor in the
atmosphere
Produces a signal based on the temperature of its surroundings
Produces a signal that depends on the pressure to which it is exposed
Produces a signal that depends on the level of light falling on it.
Produces a signal based on the invisible IR radiation falling on it
Produces a signal based on the concentration of gas or vapor .
Produces a signal based on the moisture of soil or judge if there is water
around the sensor
Produces a signal based on the field around permanent magnets, coils, and
electrical devices. It features a rotating sensor tip to measure both
transverse and longitudinal magnetic fields.
Produces a signal based on the alkalinity and acidity in a solution
57
• identify a range of sensors and describe their use in control technologies
• evaluate the use of monitoring technologies in everyday life (including: CCTV monitoring, environmental monitoring,
workplace monitoring)
Create a PPT presentation on the following monitoring technologies:
• CCTV monitoring
• Environmental monitoring
• Workplace monitoring
58
• evaluate the use of control technologies in everyday life (including: household appliances, car park barriers, traffic
lights)
Air Conditioning System
Touch screen is used to input the required temperature
1. Temperature sensor collects data about the room temperature
2. The temperature sensor sends data to the analogue to digital convertor
3. The convertor converts the analogue data into digital format
4. The convertor sends the data to the micro-processor
5. The microprocessor compares the temperature of the room to the preset
value
6. If temperature of the room is above the pre-set value the fans remain on/are switched on by the microprocessor
or microprocessor increases their speed
7. If temperature of the room is below the pre-set value the fans remain/switched off by the microprocessor
Central Heating System
1. A number pad is used to input the required temperature.
2. Temperature sensor monitors temperature of room
3. Data from the sensors is converted to digital (using an ADC)
4. The convertor sends the digital signal to the micro-processor
5. Microprocessor compares temperature data from the sensor with the pre-set value
6. If the temperature is higher/lower than preset value a signal is sent to the actuator
7. if lower microprocessor/actuator switches the heater on
8. if higher microprocessor/actuator switches the heater off
59
Refrigeration
1. A knob allows users to set the desired temperature
2. Temperature sensor monitors temperature of the fridge
3. The temperature sensor sends data to the analogue to digital convertor
4. The convertor converts the analogue data into digital format
5. The convertor sends the data to the micro-processor
6. Microprocessor compares temperature data from the sensor with the pre-set value
7. If the temperature is higher/lower than preset value a signal is sent to the actuator
8. if lower microprocessor/actuator switches the cooler on
9. if higher microprocessor/actuator switches the cooler off
Intensive Care
1. Sensors monitor the patient’s heart rate, pulse rate, body temperature, blood pressure
2. The computer is pre-set with normal range of values which is compared with the ones fed back by the sensors
3. The sensors sends data to the analogue to digital convertor
4. The convertor converts the analogue data into digital format
5. The convertor sends the data to the micro-processor
6. Microprocessor compares the data from the sensor with the pre-set value
7. Microprocessor compares the data from the sensors with the pre-set values
8. If the data received is higher/lower than the pre-set value then the computer sounds an alarm for the Medical staff’s
attention
60
Topic 4: E-safety and health and safety
• explain why personal data should be kept confidential
……………………………………………………………………………………………………………………………………………………………………………………………………
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• describe how personal data can be gathered by unauthorised persons (including: by smishing, vishing, phishing and
pharming), and how this might be prevented
What is it? How can it be used to gather
personal data?
How can it be prevented?
Sm
ish
ing
Vis
hin
g
61
What is it? How can it be used to gather
personal data?
How can it be prevented? P
his
hin
g
Ph
arm
ing
• discuss why e-safety is necessary
……………………………………………………………………………………………………………………………………………………………………………………………………
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62
• describe malware issues (including: Trojan Horse, worms, spyware, adware, rootkit, malicious bots, ransomware)
Malware Description
Trojan Horse
Worms
Adware
Malicious Bots
Ransomware
63
Exam Questions Practice
Specimen - 2017
64
• describe a range of potential health issues that could arise from using IT
Health Problem What causes it? How can it be prevented?
Repetitive Strain
Injury (RSI)
Back and Neck
Problems
65
Health Problem What causes it? How can it be prevented?
Eye Strain
Head Aches
•
66
describe a range of safety issues relating to the use of IT
Safety Issues Preventative measures
Trip hazards e.g. trailing cables
Water by machines
Overloaded sockets
Electrocution
Heavy equipment falling
Over heating
Fire
67
Topic 5: The digital divide
• Explain that the digital divide refers to the gap between people and regions that have access to aspects of modern
technology (including: telephone, television, personal computers and the internet), and those that do not or those that
have restricted access
• Explain that the digital divide can exist between:
–– people in cities and people in rural areas
……………………………………………………………………………………………………………………………………………………………………………………………………
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……………………………………………………………………………………………………………………………………………………………………………………………………
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–– the educated and the uneducated
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–– socioeconomic groups
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–– more and less industrially developed nations
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68
–– high and low performance computers, wireless connections
……………………………………………………………………………………………………………………………………………………………………………………………………
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Exam Questions Practice
Specimen - 2017
69
Topic 6: Using networks
6.1 Network types
• discuss the advantages and disadvantages of networking computers
Advantages Disadvantages
•
Compare the characteristics of a local area network (LAN) with a wide area network (WAN)
Local area
Network (LAN)
Wide Area
Network (WAN)
• describe client-server and peer-to-peer networks
70
71
• describe the characteristics and purpose of virtual private networks (VPN)
72
• discuss the advantages and disadvantages of different network types (including: client-server, peer-to-peer, VPN)
Advantages Disadvantages
Pe
er
to P
ee
r
Clie
nt
Se
rve
r
Vir
tua
l P
riva
te N
etw
ork
73
• describe the characteristics and purpose of the internet, intranets and extranets
Definition Purpose and Characteristics
Intr
an
et
Extr
an
et
Inte
rne
t
74
• describe how the internet is used for communication (including: IM, VOIP and news services)
Definition Features
VO
IP
IM
Ne
ws S
erv
ice
s
75
• discuss the benefits and drawbacks of using the internet
Advantages Disadvantages
• Explain the difference between the internet and the World Wide Web
……………………………………………………………………………………………………………………………………………………………………………………………………
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76
Exam Questions Practice
Specimen - 2017
77
• discuss the advantages and disadvantages of mobile networks
Advantages Disadvantages
78
6.2 Video and web conferencing
• describe how to set up a video conference
Hardware required:
Software required:
Process of setting up a video conference
79
• describe how to set up a web conference
Hardware required:
Software required:
Process of setting up a web conference
80
• describe the use of networks in video and web conferencing (including: Integrated Services Digital Network (ISDN),
LAN, WAN, VPN, 802.11 a/b/g/n (wireless), Asynchronous Digital Subscriber Lines (ADSL), Synchronous Digital
Subscriber Lines (SDSL), 3G/4G mobile networks)
Use of network in video and web conferencing
Inte
gra
ted
Se
rvic
es D
igita
l
Ne
two
rk (I
SD
N)
80
2.1
1 a
/b/g
/n
(wir
ele
ss)
Asyn
ch
ron
ou
s D
igita
l S
ub
scri
be
r L
ine
s (A
DS
L)
WAN LAN 3G/4G mobile networks Synchronous Digital Subscriber
Lines (SDSL)
Desc
riptio
n
81
82
• discuss the impact of video conferencing on society (including: the general public, legislation, education, medicine,
business, media)
Positive Impact of Video Conferencing Negative Impact of Video Conferencing
Ge
ne
ral
pu
blic
Le
gis
latio
n
Ed
uca
tio
n
Me
dic
ine
Bu
sin
ess
83
• describe how data is transmitted and converted in a video conference (including: use of codecs)
84
Topic 7: Expert systems
• describe the components of an expert system
Description
Kn
ow
led
ge
Ba
se
Exp
ert
Infe
ren
ce
E
ng
ine
Use
r In
terf
ace
• explain how the components of an expert system produce possible solutions
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85
• explain how an expert system can be used by organisations
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• describe the terms backward chaining and forward chaining
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86
• explain the use of master and transaction files (including in: payroll and customer orders)
A payroll system is software which organizes all the tasks of employee payment and the filing of employee taxes. It
involves:
• Keeping tracking of hours
• calculating wages
• calculating taxes and deductions
• Printing of pay slips
• Transferring wages to bank accounts
• Paying employment taxes to the government.
Transaction Files
Contains the transactions; changes that are supposed to be made to the data in the
master file. For example, each of the following employees have earned the following for
this particular week.
Each transaction has a code which tells the computer what to do with the data in the
transaction file. For example:
A – Addition - Add a record
C – Change – Change a record
D – Delete a record
Master Files:
Holds the actual data that is supposed to be processed and holds the resultant data after the process is completed
(updated salaries from the transaction file.) The data can be organized using keys.
87
Updating a Master File
1. The transaction file is sorted in the same order as the master file e.g. By an ID such as employee number
2. The computer reads the first record record in the transaction file and the first record in the master file
3. If the IDs don‘t match the computer writes the master file record to the new master file
4. Then write the information from the old master file with the updates from the transaction file to the new
master file.
5. If the transaction relates to rate of pay , the computer calculates the pay using the rate of pay from the
master file and hours worked from the transaction file. It also deducts any taxes from total pay.
6. Processed record is written to master file and the process is repeated until the end of the master file
7. If transaction relates to deletion or amendment the then the old master file record is not written to the new
master file
8. If amendment or insertion is required then the data in the transaction file is written to the new master file
88
• analyse the different types of processing and their uses (including: batch, online, real processing)
Description Examples
Ba
tch
On
lin
e
Re
al-
tim
e
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