• backups/dumps of files
• copy of files on CD/tape streamer
• file generations

• less errors on input
• requires less storage space
• validation
• quicker to input
• quicker to find

Shielded twisted pair cable:
A twisted pair cable is made up of four pairs of twisted copper wires, a shielded twisted pair cable applies a shield to each one of the pairs on a cable or to all of the pairs together. This shield can reduce EMI (electromagnetic interference), which would be emitted from heavy machinery. This increased data transmission quality in the workshop. STP can also reduce crosstalk.

• Used to resize the image
• Used to rotate the image
• Used to move the image

System Stability: Computers require a consistent and stable power supply to function properly. Fluctuations or interruptions in the power source can cause various issues that can disrupt the computer's operation or lead to hardware damage.

a. Data Loss: Sudden power outages or voltage fluctuations can cause the computer to shut down abruptly, resulting in data loss if unsaved work is not properly stored. This can be particularly problematic when working on critical tasks or handling important files.

b. Hardware Damage: Power surges or inconsistent power supply can damage the computer's internal components, including the motherboard, CPU, memory, and storage devices. These damages can result in system instability, reduced performance, or even complete hardware failure.

c. Operating System Corruption: Abrupt power loss or inconsistent power supply can corrupt the operating system files, leading to system crashes, error messages, and instability. This may require system repairs or reinstallation of the operating system.

d. Component Lifespan: Inconsistent power supply can put unnecessary stress on computer components, shortening their lifespan. Frequent power fluctuations or surges can cause wear and tear on various parts, reducing their efficiency and overall longevity.

• Radiowaves are omnidirectional while microwaves propagate in one direction at a time(unidirectional)
• Radiowaves can be propagated over long distances through sky mode while microwaves require a relay satellite to amplify and retransmit the microwaves signals to the receiver earth station

• A denial of service strategy usually works flooding the target host or network with traffic until the target can’t respond or crashes. The targeted systems operations are affected when users are unable to access information systems and or network services

(a) Disk mirroring- Data is written on two or more disks simultaneously.

(b) Encryption - Contents are scrambled so they cannot be understood without a decryption key

(c) Backup - A copy of the data is taken and stored in another location

• VM is used when RAM is full  i.e part of the secondary storage used as (temporary) RAM/VM
• Data from RAM is moved to the secondary storage/VM (to make space in RAM)
• RAM can then be filled with new data
• When data in VM is needed it is moved back to RAM

1. (a)State what is meant by the terms:

Parallel data transmission

• 8 bits/1 byte/multiple bits sent at a time  

1. using many/multiple/8 wires/lines

Serial data transmission

• one bit sent at a time  
• over a single wire

b) Give one benefit of each type of data transmission.

• Parallel - faster rate of data transmission

Serial

1. -more accurate/fewer errors over a longer distance
2. -less expensive wiring  
3. less chance of data being skewed/out of synchronization/order

Give one application of each type of data transmission. Each application must be different

Parallel

• sending data from a computer to a printer
•  internal data transfer (buses)

Serial

• connect computer to a modem

State what is meant by the term USB

• universal serial bus

Describe two benefits of using USB connections between a computer and a device.

• -devices are automatically detected and configured when initially attached
  • Impossible to connect device incorrectly/connector only fits one way
  • has become the industry standard
  • supports multiple data transmission speeds
  • lots of support base for USB software developers
  • supported by many operating systems
  • backward compatible
  • faster transmission compared to wireless

DVD - optical media which use one spiral track; red lasers are used to read and write data on the media surface; makes use of dual-layering technology to increase the storage capacity

ROM - non-volatile memory chip; contents of the chip cannot be altered; it is often used to store the start-up routines in a computer (e.g. the BIOS)

SSD/ Solid State Drive/memory (SSD): a non-volatile memory device that uses NAND flash memories (which consist of millions of transistors wired in series on single circuit boards)

Blue Ray -  optical media that uses blue laser technology to read and write data on the media surface; it uses a single 1.1 mm polycarbonate disc

Viruses, pharming and phishing are all examples of potential Internet security issues.
Explain what is meant by each of these three terms.

Virus

• - program/software that replicates/copies itself
• – can delete or alter files/data stored on a computer
•  – can make the computer “crash”/run slow

Pharming - malicious code/software installed on a user’s hard drive/actual webserver

 – this code redirects users to a fake website (without their knowledge)

 – to obtain personal/financial information/data

Phishing - legitimate-looking emails sent to a user – as soon as the recipient opens/clicks on the link in the email/attachment,  the user is directed to a fake website (without their knowledge) – To obtain personal/financial information/data

control bus- this bus carries signals used to coordinate the computer’s activities

address bus - this uni-directional bus carries signals relating to memory addresses between processor and memory

data bus - this bi-directional bus is used to exchange data between processor, memory and input/output devices

The seven stages in a von Neumann fetch-execute cycle

• the PC (program counter) contains the address of the next instruction to be fetched
• the address contained in the PC (program counter) is copied to the MAR (memory address register) via the address bus
• the instruction is then copied from the memory location contained in the MAR (memory address register) and is placed in the MDR (memory data register)
• the entire instruction is then copied from the MDR (memory data register) and placed in the CIR (current instruction register)
• the value in the PC (program counter) is then incremented so that it points to the next instruction to be fetched
• the address part of the instruction is placed in the MAR (memory address register)
• the instruction is finally decoded and is then executed

Modern LCD monitors and televisions use LED-backlit technology.
Give two advantages of using this new technology compared to the older cold cathode fluorescent lamp (CCFL) method

• no need to warm up
• – whiter tint/more vivid colours/brighter image
• – higher resolution
• – much thinner monitors possible/lighter weight
• – more reliable technology/longer lasting
• – uses much less power/more efficient

• where the new system is completely different from the old one
• if there has been extensive testing of the system and the system analyst has confidence in its functionality
• If the system is not critical

• connecting wireless headphone to a phone
• Using a wireless mouse, keyboard etc
•  

Blagging

• This is where a victim is tricked/persuaded by a fraudster to give their details or payment information for a false reason/purpose;

Phishing

• This is where the victim receives and responds to communication that appears to be from a valid or known source but is in fact fraudulent. (It allows the fraudster to capture private information before the victim realises);

Shouldering

• This is where someone watches and records\remembers a victim entering their pin or security information such as passwords. (They can then use this information to gain access to a system)

a)  i)  Explain what is meant by the term volatile memory                                                            (1mark)

• Memory content is lost when the power is turned off

ii) What is normally stored in the non-volatile part of a computer’s main memory                       (1mark)

• The Computer’s BIOS

b) Explain why having cache memory can improve the performance of the CPU                         (2mks)

• Frequently used data/instructions are store in the cache; Meaning they don’t have to be fetched from the main memory;
• Data/instructions stored in the cache memory can be accessed faster (than data/instructions stored in the main memory) MAX 2

• Because it will be subject to movement  and it does not use mechanical/moving parts

          OR

• Solid state storage is smaller/more compact so better suited for a wearable device

          OR

• Doesn’t have moving parts  because they could be disrupted during use

• holds an indexed sequence of variables of the same data type
• Arrays can be used to store values of the same data type and the array is then used as a singular variable to increase efficiency

• it is easier / quicker to read/write/understand
• it is easier / quicker to debug
• code is portable.

Describe how the computer on board the aeroplane uses GPS to find its exact location

– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:

Give two benefits of using GPS in this application

– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency

• Implementation

(i) Unexpectedly halts the program. Run time (execution)

(ii) The program produces the wrong output.  Logical
 (b) Another error can result from incorrectly using the rules or grammar of the programming language.

(i) Name this error. Syntax

(ii) State when this error is detected.

Syntax error is detected during translation into executable code / attempted to run but fails