computer systems

Question 1

how to work out range of values in twos complement

Answer 1

-2⁸-¹ to (2⁸-¹)-1

Question 2

twos complement from negative denary

Answer 2

find positive number

flip 1’s and 0’s

flip 1’s and 0’s from right most 0

Question 3

twos complement from binary

Answer 3

flip 1’s and 0’s

flip 1’s and 0’s from right most 0

Question 4

determining whether exponent positive or negative

Answer 4

mantissa decimal moved left = positive

mantissa decimal moved right = negative

Question 5

side of padding of floating point representation

Answer 5

sign- 1 bit

mantissa- 15 bit

exponent- 8 bit

Question 6

what does the mantissa determine?

Answer 6

dictates precision of a number

more bits allocated, more precise number

Question 7

what does the exponent determine?

Answer 7

dictates range of numbers that can be represented

more bits added, bigger the range

Question 8

increased mantissa, decreased exponent means…

Answer 8

increased precision

decreased range

Question 9

decreased mantissa, increased exponent means…

Answer 9

decreased precision

increased range

Question 10

disadvantage of extended ASCII

Answer 10

only 8 bit code meaning maximum of 256 characters can be represented

Question 11

3 advantages of unicode

Answer 11

16 bit code per character with maximum of 65,536 characters

first 128 characters of unicode are identical to ASCII, allowing for compatibility

universally accepted by computing platforms

Question 12

disadvantage of unicode

Answer 12

uses more storage space per character for non- ASCII characters

Question 13

advantage and disadvantage of bitmapped graphics

Answer 13

great for representing realistic images

images become blurred (pixelated) with scaling

Question 14

advantage and disadvantage of vector graphics

Answer 14

not blurred by scaling

cant create photo realistic images very well

Question 15

4 factors that can improve performance of computer system

Answer 15

number of processors (cores)

width of data bus

cache memory

clock speed

Question 16

how can the number of processors improve performance of a computer system?

Answer 16

more cores a processor has, more sets of instructions the processor can receive and process at the same time

Question 17

how can the width of data bus improve performance of a computer system?

Answer 17

increasing data bus from 32 to 64 bit means computer can transfer twice as much information in a single operation

Question 18

how can cache memory improve performance of a computer system?

Answer 18

more cache memory, the more data that can be stored closer to the CPU, providing faster access time

Question 19

how can clock speed improve performance of a computer system?

Answer 19

higher the clock rate, the faster the computer may complete

Question 20

fetch execute cycle
(memory read operation)

Answer 20

processor sets up address bus with required address

processor activates READ line on control bus

address on RAM is located and opened, instruction put onto the data bus

instruction then interpreted by decoder and executed

Question 21

fetch execute cycle
(memory write operation)

Answer 21

processor sets up address bus with required address

processor activates WRITE line on control bus

address on RAM is located and opened

instruction to be written is loaded onto data bus, sent to the RAM and stored

Question 22

3 ways heating systems are energy efficient

Answer 22

remote control settings allows heating to be changed outside the home

adjusts heating depending on room usage

can be adjusted in comparison to weather

Question 23

3 ways traffic control systems reduce effect on environment

Answer 23

smart traffic lights

smart motorways

satellite navigation

Question 24

2 car management systems that reduce the effect on the environment

Answer 24

start stop systems

engine control units

Question 25

3 acts of the computer misuse act 1990

Answer 25

unauthorised access to computer material

unauthorised access with intent to commit a further offence

unauthorised modification of programs or data on a computer

Question 26

what are tracking cookies?

Answer 26

small text files that websites store on your device to track your online activity

Question 27

what is a DOS attack?

Answer 27

denial of service attack perpetrated by single attacker

disrupt normal functioning of a computer by overwhelming system with a flood of requests or data

Question 28

what is a DDOS attack?

Answer 28

distributed denial of service attack is the same as a DOS attack, yet uses a network of computers to attack a single system

much more powerful

Question 29

3 symptoms of a DDOS attack

Answer 29

slow or unresponsive system

inability to access services

internet disconnection

Question 30

3 effects of a DDOS attack

Answer 30

opportunity for other attacks

customers may choose competitor

business suffer reputational damage

Question 31

3 types of DDOS attacks

Answer 31

bandwidth consumption- consumes available bandwidth by overloading system with excessive amounts of data

resource starvation- exhausts things in system like CPU, memory space etc, resulting in system crashes

domain name service- DNS server translates domain names into IP addresses, disrupting the usual translating process

Question 32

3 reasons for a DOS attack

Answer 32

financial

political

personal

Question 33

what is encryption?

Answer 33

converting data into secret code to keep it secure, using both public and private keys

Question 34

what are public and private keys?

Answer 34

public key is freely shared and used to encrypt data

private key kept secret and used to decrypt data

Question 35

what is a digital certificate?

Answer 35

secure electronic document that verifies the authenticity and identity of an entity

Question 36

what is a digital signature?

Answer 36

unique digital stamp that ensures integrity and authenticity of electronic data