🟣| Computer Systems Flashcards
What are the advantages of bitmap graphics?
3
- Can edit down to individual pixel level
- Adding extra detail does not increase file size
- Can create photo realistic images
What are the disadvantages of bitmap graphics?
2
- Very large file size for individual pixel storage
- Resolution dependant, so pixelated when scaled larger
What are the advantages of vector graphics?
3
- Small file size as only attributes are saved
- Resolution independent, so doesn’t pixelate when scaled larger
- Objects can be layered
What are the disadvantages of vector graphics?
2
- Difficult to make realistic images with just objects
- Adding extra objects increases file size
What happens if the number of bits allocated to the exponent increased?
Increases the range of the number, but decreases the number of bits available for the mantissa so the precision of the number is decreased
What happens if the number of bits allocated to the mantissa is increased?
Increases the precision of the number, but decreases the number of bits available for the exponent so the range of numbers is decreased
What are the steps of the fetch execute cycle?
4
- The processor sets up the address bus with the required address
- The processor activates the read line on the control bus
- An instruction is fetched from the memory location using the data bus and stored in the instruction register
- The instruction in the instruction register is then interpreted by the decoder and carried out
What factors affect system performance
4
- Number of cores (processors)
- Width of data bus
- Cache memory
- Clock speed
How does the number of cores affect system performance?
2
- The more cores a processor has, the more sets of instructions the processor can receive and process at the same time, which improves system performance
- A dual core processor is not as fast as a single processor running at twice the speed as it is not always possible to share some tasks equally between the cores, which reduces efficiency
How does the width of the data bus affect system performance?
2
- Data bus is a set of parallel wires that connects the processor with memory and other hardware devices
- By increasing the data bus from 32 wires to 64 wires, the computer can transfer twice as much information at one time which improves the system performance of the computer
How does cache memory affect system performance?
2
- Cache memory is a small amount of fast accessible memory, usually with or close to the processor
- The processor checks the cache for data or instructions before accessing the main memory, which is faster and can result in fewer accesses to slower main memory
How does clock speed affect system performance?
3
- Clock pulses are used to trigger components to take their next step,
- The clock rate is the frequency at which the clock generates pulses
- The higher clock rate, the faster the computer may complete a series of instructions
What are tracking cookies?
Cookies that record your details and are sent back to the author of the cookie - most are for collecting marketing data or targeting adverts
How do tracking cookies become a security risk?
- Tracking cookies can be set by programmers to send them usernames and personal data, which can be used in identity theft
What is a DoS attack?
A deliberate attempt to prevent legitimate users of a network from accessing the services provided by a server or connected systems by bombarding a server with network messages to keep it busy
What are the types of DoS attack faults?
3
- Bandwith consumption
- Resource starvation
- DNS attack
DoS Attacks:
Bandwith Consumption
Using all of the websites available bandwidth
DoS Attacks:
Resource Starvation
An attempt to use enough server resources to make the system unresponsive
DoS Attacks:
DNS Attack
Modification of DNS record settings to point to a rogue DNS server
What are the reasons for carrying out a DoS attack?
3
- Financial - bringing down a commercial website will cost that company money
- Political - prevent access to the website of a political rival
- Personal - the attacker may have a personal grudge against the owner of the website
What are digital signatures?
3
- Created when a message is sent using a private key.
- The recipient can be confident that the sender is who they say they are.
- The recipent can be confident that the message was not altered in transit
What are digital certificates?
2
- Authenticates a person, allowing them to exchange data over the Internet using a public key.
- Issued only by trusted entities (certification authority)
