Topic 1 - Data Processing and Information
Explain the difference between a direct data source and indirect data source.
Direct - Data that is collected for the purpose for which it will be used.
Indirect - Data that was collected for a different purpose (secondary source).
Give an example of when a menu based interface might be used.
A menu interface is a series of menus put together to process an action.
For example, when paying by card there may be the option to add a tip before paying the final bill, the options are yes or no and are represented by a menu.
This is a very simple interface with limited functionality.
Define the term "sensor".
An input device that collects data from the surrounding physical environment.
Define the term "algorithm"
A set of instructions or steps to be followed to achieve a certain outcome.
List the eight different kinds of malware.
Virus
Trojan
Spyware
Rootkit
Bots
Worms
Ransomware
Adware
What are the five attributes that impact the quality of information?
Accuracy
Relevance
Age
Level of detail
Completeness
Give one advantage and one disadvantage of using off-the-shelf software.
The development cost of off-the-shelf software is spread between all the customers who purchase it at a specified price, which means the cost is lower.
Off-the-shelf software is immediately available, so the customer can start using it straight away.
Some tasks that the customer needs to carry out may not be possible and there will be lots of features that the customer never uses.
The software may not be compatible with existing hardware, software and data used by the customer.
The software will have been used by thousands of customers and bugs will have been identified and fixed and patches will be released as more bugs are found so that the software runs as expected.
Customers will be able to get support from a wide range of sources including telephone support, discussion forums and online training.
Explain the difference between a monitoring system and control system.
Monitoring system: A system that observes and often records the activities in a process.
Control system:A system that manages or regulates a process by physically changing aspects of the system depending on the data collected.
What are the four main flowchart symbols? (draw and label)
rectangle - process
diamond - selection
parallelogram - input/output
Explain what is meant by the term "virtual private network".
An encrypted connection that can be used to send data more securely across a network.
Explain how encryption is used with emails/
Email uses asymmetric encryption. This means that recipients of emails must have the private key that matches the public key used to encrypt the original email.
Both the sender and recipient need to send each other a digitally signed message that will add the person’s digital certificate to the contract for that person.
Encrypting an email will also encrypt any attachments.
Explain the process of disk defragmentation.
Fragmented files:
As a HDD gets used, files are kept together in storage on the same cylinder or adjacent cylinders.
When files are deleted, gaps are left on the disc.
As files grow in size, they use up more space on the disc and this may no longer be on the same or adjacent cylinder and will be spread across on many clusters.
When all the cylinders have been used, the only space to store files is within the gaps.
If the gaps are not big enough, then files have to be split across gaps, meaning they become fragmented.
The problem with this is that when opening the file, the access arm of the HDD has to keep moving to different locations which makes opening the file a slow process.
The solution = defragmentation.
Defragmentation:
A defragmentation utility will reorganise all the files so that each file is contiguous (kept together).
It does this by moving fragmented parts of files and small files to free space on the disc and creating space on whole cylinders or adjacent cylinders.
It will then move the defragmented files to a place where the whole file is kept together.
This can significantly improve the performance of a computer system.
Explain how a monitoring system can be used to check the temperature levels in a car engine.
The temperature range will be set, e.g. 0-20 degrees
The sensor will then take the temperature of the car engine
This reading will be compared to the range
If it is within the range, nothing will happen and the sensor will continue to take readings at set intervals
If it isn't within range, the car engine light will turn on, on the dashboard, alerting the driver that there is an issue that needs to be addressed.
Explain the difference between a count-controlled loop and a condition-controlled loop.
count - A loop where you know the number of times it will run.
condition - A loop that runs based on a condition.
Explain the difference between phishing and pharming.
Phishing:
Phishing is when a person sends a legitimate looking email to a user.
The email contains a link to a website that also looks legitimate.
The user is encouraged to click the link and to input personal data into a form on the website.
The email could simply ask for the user to reply to the email with their personal data.
The user is tricked into giving their personal data to a source that they believe is legitimate, however, both the email and website are from a fake unauthorised source.
The personal data that is input is then collected by an unauthorised person. This person can then use this data for criminal acts such as fraud and identity theft.
Intimidation or a sense of urgency is often used in phishing, telling the user that they must click on the link immediately otherwise there will be further issues.
The aim of phishing is to steal the user’s personal data.
Pharming:
Pharming is when an unauthorised user installs malicious code on a person’s hard drive or server.
The code is designed to redirect a user to a fake website when they type in the address of a legitimate website.
The fake website is designed to look like the legitimate website to trick the user and make sure that they’re not aware they have been redirected.
The user will then enter their personal details into the fake website without realising.
A common technique used in pharming is called domain name server (DNS) cache poisoning, this exploits vulnerabilities in the DNS and diverts the internet traffic intended for a legitimate server toward a fake one instead.
The unauthorised user needs to find a way to install the malicious code on the computer. They often hide the code in an email attachment or link.
Explain the process of a parity check verification.
•Parity Checking is one method used to check whether data has been changed or corrupted after data transmission.
•This is based on the number of 1-bits in a byte of data.
•The parity can either be called EVEN (an even number of 1-bits in the byte) or ODD (an odd number of 1-bits in the byte).
•One of the bits in the byte is reserved for a parity bit.
•The parity bit is set according to whether the parity being used is even or odd.
State two differences between a compiler and an interpreter.
Compiler
Translates source code into object code all at once in advance of execution.
Compiled object code will only work on the OS it has been compiled for.
Object code is ready to be executed without delay.
Compiling can take a long time, which is not appropriate for on-the-fly testing.
Errors are reported after compilation has completed.
The source code is optimised to run as efficiently as possible.
Interpreter
Translates source code into object code one line at a time.
Source code can be translated into object code for more than one OS.
Object code has to be generated, so additional time is added to the execution time.
Only the required code needs to be interpreted, so this is efficient for on-the-fly testing.
Errors are reported as they are found during the interpretation.
Explain how an actuator is used in a burglar alarm control system.
The alarm is set
The sensors will detect sound/movement
The microprocessor will process any readings from the sensor
If there is sound/movement detected, it will tell the actuator to turn on the alarm, lock the doors, phone the police etc.
If there is no sound/movement detected, no message will be passed onto the actuator and the sensors will continue to monitor the situation.
Define the term "subroutine"
A set of instructions that have an identifier and that are independent from the code. It is called from another part of the program and returns control when it is finished.
Explain the difference between antivirus and a firewall.
Antivirus - Software that is used to identify a virus on a computer and remove it.
Firewall - A security measure that can be implemented to monitor traffic into and out of a computer and prevent external users gaining unauthorised access to a computer system.
Explain online/interactive processing and give an example.
Interactive means that the user and the computer are communicating together.
The user inputs data and the computer responds with an output.
While processing takes place, data is stored in RAM and is not saved to non-volatile memory until the user saves the data.
The computer will process the data as quickly as possible so that the user is able to see/hear the results of the processing.
Examples of interactive processing:
Word processing
Analysing spreadsheet data
Browsing the web
Checking emails
The processing time is very short (approx. thousandths of a second).
Explain the difference between CISC (complex instruction set computing) processors and RISC (reduced instruction set computing) processors.
CISC (complex instruction set computing) processors will have a single instruction doing many things at once whereas RISC (reduced instruction set computing) processors will have a single instruction that does very little but manages the instruction efficiently.
There are three main categories of result that can be given by a sensor; offset, sensitivity and linearity. Define these three results.
Offset - this means that the readings are higher or lower than the ideal reference.
Sensitivity - this means that the readings change over a range at a different rate to the ideal reference
Linearity - this means that the readings are directly proportional to the ideal reference.
What is an identifier?
The name given to a variable, subroutine or function.
How could you minimise the risks of a worm?
Worms often exploit software vulnerabilities in a computer, usually located in the OS or applications.
You should regularly check for and install updates for your OS and applications. You can set this to happen automatically.
The same guidelines apply as phishing.
Antivirus software can normally check for worms too.
Worms can spread by network connections. Disconnecting your computer from a network, when the network resources are not required, can keep it safe during this time.