Computer Systems Flashcards
What are the two forms of representing text?
- Extended ASCII
- Unicode
How many bits does extended ASCII use?
8 bits
How many bits does unicode use?
16 bits
What is an advantage of extended ASCII?
Less storage requirements
What is a disadvantage of extended ASCII?
Can’t represent as many characters
What is an advantage of unicode?
Can represent more characters
What is a disadvantage of unicode?
Requires more storage
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 located 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 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 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?
3
- 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?
- 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
How do heating systems have a good environmental impact?
2
- Smart heating systems can be connected to wifi, so heating can be turned off using an app if you are away from home which reduces the amount of heat being wasted
- Smart heating systems can also use activity sensors to learn temperature preferences, so only necessary heat is used
How does smart traffic control have a good impact on the environment?
2
- Uses a variety of information from cameras, sensors and traffic signals to try keep traffic moving, reducing the amount of harmful emissions
- Cars with individual navigation systems use satellite information on traffic flow to guide drivers away from traffic congestion and on to more free flowing routes
How do car management systems have a good impact on the environment?
Start-Stop systems automatically shut down the engine when the car is not moving, this reduces the amount of time the engine spends idling which reduces fuel consumption and emissions
What is the act that makes unauthorised activities on computers illegal?
Computer Misuse Act 1990
What offences can one be prosecuted for under the computer misuse act?
4
- Unauthorised access to computer material
- Unauthorised access to a computer without permission with intent to commit further criminal offences
- Unauthorised modification of programs or data on a computer
- Making, supplying or obtaining anything which can be used in computer misuse offences
