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Higher Computing full course Revision cards > Computer systems > Flashcards

Computer systems Flashcards

1
Q

State what is meant by a sign bit?

A

A sign bit is defined as the first digit of a binary number which indicates if the number is a positive number or a negative number

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2
Q

State what having a sign bit of 1 indicates about a number?

A

Having a sign bit of 1 indicates that negative number = true, meaning that the number will be negative.

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3
Q

State what is meant by having a sign bit of 0?

A

A number with a sign bit of 0 means that negative = false, this means that the number will be a positive number

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4
Q

Describe the twos complement convention to determine the range of values for a positive number?

A

0 to (2 to the power of the number of bits in the binary number) -1

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5
Q

Describe the twos complement convention to determine the range of values for a negative number?

A

We still have only the 2 to the power of number of bits in the binary number, values but this time they are split evenly across positive and negative numbers e.g and 8 bit negative number will have a range of -128 to 127

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6
Q

State the mantissa of this number 1.00000001 * 2^11110?

A

The mantissa is the main number meaning it will be the number in the left 100000001

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7
Q

State the exponent of the number 1.00100101 * 2^1110

A

The exponent is the number on the right meaning the exponent is the power (1110)

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8
Q

State the effect of increasing the available number of bits for the mantissa will have?

A

An increase in the available number of bits for the mantissa will increase the precision of the number

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9
Q

State the effect that increasing the available number of bits for the exponent would have?

A

An increase in the available number of bits for the mantissa means that you increase the range of the number

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10
Q

State the effect of a decrease in the available number of bits for the mantissa would have?

A

Decreasing the available number if bits for the mantissa would reduce the precision of the number

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11
Q

State the effect of a decrease in the number of bits available for the exponent?

A

A decreased number of bits for the exponent means that the range of the number will decrease

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12
Q

Describe how you determine the sign bit in floating point representation?

A

The sign bit will be a 0 if the number is positive and a 1 if the number is negative

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13
Q

Describe how you determine the mantissa in floating point representation?

A

To find the mantissa you remove the decimal point for the number and add on any aditional 0s at the end of the number.

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14
Q

Describe how you would determine the exponent in floating point representation?

A

In floating point representation we look at the number of places that the decimal point has moved
- If the decimal point has moved to the left then the exponent is positive
- If however the decimal point has moved to the right then the exponent is negative

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15
Q

Explain some of the similarities and differences between unicode and ASCII?

A

Both unicode and ASCII are methods of storing characters as binary values ASCII only stores 2^7 values and extended ASCII will store 2^8 however this is not enough values to include characters from other languages or emojis. Hence unicode uses 16 bits per character meaning that they have a 2^16 values that they could represent. The increased number of bits means that they can represent a larger number of characters useful for storing emojis or symbols for other languages of the world.

(Unicode has more bits and can therefore represent more characters)

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16
Q

State what is meant by a bit map?

A

A bitmap is defined as a grid of pixels

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17
Q

Explain what a bitmap does?

A

A bitmap is a grid of pixels where each individual pixel has a binary value that determines the colour of that given pixel. Bitmaps have a large file size as they must store each pixel in an image as a binary value with 24 bits per pixel.

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18
Q

State what is meant by a vector?

A

A vector consists of objects and attributes, Vectors are stored as separate objects. This means that they can be layered without overriding what is underneath and they do not leave unwanted gaps

19
Q

State what is meant by an image being resolution independent?

A

An image that is resolution independent means that the image can be redrawn at any resolution.

20
Q

Explain why vectors can be described as being resolution independent?

A

As they can re resized without causing pixelation as vectors are stored as individual objects meaning that they can be reshaped and resized without losing any quality.

21
Q

State what the role of an address bus is?

A

The address bus is a bundle of wires that carries the identity of memory locations.

22
Q

State the role of a data bus?

A

the data bus will retrieve data from the memory location that it is given and return this data to the CPU.

23
Q

State the role of the control bus?

A

The job of the control bus is to indicate if the processor is reading from or writing to the main memory.

24
Q

State the 4 components that make up the CPU?

A
  • Cashe
  • Registers
  • ALU
  • Control unit
25
Q

Describe what the cashe is?

A

Cashe is a small amount of very fast but expensive memory that is stored on the same chip as the processor. It stores frequently used data and instructions and if the processor finds what it is looking for here then it will no longer need to look for this data in the main memory saving time and speeding up the entire process.

26
Q

State the four factors at higher that influence system performance?

A
  • Number of processors
  • Clock speeds
  • Width of data bus
  • Size of cashe memory
27
Q

Explain why increasing clock speed will improve system performance?

A

Increasing clock speed means that the processor will get through its set of instructions more quickly improving the performance. The faster the pulse rate of the clock speed the more instructions can be processed in a shorter amount of time

28
Q

Explain why increasing the number of processors will improve system performance?

A

A dual core or quad core processor will enable a processor to process more data and instructions on each clock cycle than an equivalent single core processor. This means that adding more cores improves system performance.

29
Q

Explain why increasing the width of the data bus improves systems performance?

A

Increasing the width of the data bus can increase the amount of data that is transferred between the main memory and processor in each clock cycle which in turn will improve the system performance as less fetch execute cycles will be required.

30
Q

Explain why increasing the size of the cashe memory improves system performance?

A

Cashe memory is fast memory that is stored on the same chip as the processor, meaning that it can be checked for frequently used data or instructions, if these are found this is called a cashe hit, and means that the system does not need to run a fetch execute cycle improving efficiency , lager cashe memory means that more cashe hits can occur meaning that the processor is not required to go to the main memory as frequently, which improves the overall system performance.

31
Q

State the names of the 2 variations of the fetch execute cycle that you are required to know?

A
  • Memory read (memory is read and data is transferred to the processor)
  • Memory write (Data is being sent from the processor to be stored in the main memory)
32
Q

Explain the steps in the fetch execute cycle for a memory read?

A
  • The processor will set up the address bus with the required address
  • The processor will activate the read line on the control bus to read at the address given by the address bus
  • The instruction stored at that address is fetched by the data bus and stored in a register in the processor
  • The instruction will then be decoded and executed on the processor
33
Q

Explain the steps of the fetch execute cycle for a memory write?

A
  • The processor sets up the address bus with the required address
  • The data bus receives the data that is required to be stored in the main memory
  • The processor activates the write line on the control bus to write at the given address by the address bus
  • the data bus will transfer the data to the address specified
34
Q

Explain the environmental impact of Intelligent heating systems?

A

There is no reason to heat a room that does not have anyone in it some heating technologies can detect if a person is in a room via motion in the room and switch off the heating to save energy. Other intelligent heating systems will recognise users patterns and behaviors and will turn down the heating in rooms that are not used as frequently.
Most intelligent heating systems are connected to some weather software that can help them to determine if the heating needs to be on depending on the weather. This acts to save energy which makes this process more environmentally friendly

35
Q

Explain the environmental impact of intelligent traffic systems?

A

When cars stop and start more emissions occur hence it is environmentally friendly to ensure that traffic continues to move. Intelligent traffic systems use sensors to help to keep traffic moving and apps on phones can indicate areas of congestion to prevent traffic jams.

36
Q

Explain how car management systems can have a positive environmental impact?

A

Car management systems can help drivers to reduce their fuel usage, start stop systems can detect when a car is at traffic lights and automatically stop the engines to save fuel. car management systems can also use sensors to detect the air to fuel ratio ensuring the optimum mix to reduce emissions all helping to be more environmentally friendly.

37
Q

State the three offences under the computer misuse act of 1990?

A
  • Unauthorised access to computer material
  • unauthorised access with intent to commit further offences
  • unauthorised modification of computer material
38
Q

Explain how encryption keys work?

A

There exists both a public key and a private key, every user has both a public key and a private key. Everyone has access to your public key and you can use your public key to encrypt a message where only someone with the private key is able to decrypt the message. You do not have the private key meaning that if you send a message using a public key only someone with the private key is able to decrypt the message and you do not have access to the private key meaning that only the person that you have sent the message to is able to decrypt the message that you have sent to them.

39
Q

Explain how a digital certificate can be used?

A

Digital certificates involve encrypting a message using your private key meaning that this ensures that the message has come from you. You can use a digital certificate to prove that a key belongs to you.

Digital certificates can be used to send you a key and a digital signature can be used to ensure that the message was sent from an authentic source

40
Q

Explain what cookies are and what they do?

A

Cookies are small text files that store data about you as a user and how you use a particular website, they store information such as viewing history, products you have shown interest in or other data that personalises the browsing experience to yourself.

There are some risks assosiated with the use of cookies, when data is sent between the browser and your computer unencryped meaning that the data can be intercepeted and your viewing habits can be seen by less trustworthy people

41
Q

State the risk assosiated with the use of cookies?

A

Unwanted or unauthorised access to your personal data

42
Q

State what is meant by a DOS attack?

A

A DOS (denital of service attack) is one that bombards a website with so many requests that the website is unable to serve its real users, the goal of these attacks is to force the website offline.

43
Q

Explain how a DOS attack actually works to make a site go offline or slow a site down?

A
  • Consuming bandwidth
  • Resource starvation (caused by millions of fake users)
  • attacking the DNS preventing users from accessing the website
44
Q

State some of the effects of a DOS attack?

A
  • Financial losses for a business as a result of loss of customers and spending money to fix the issue
  • reasons for DOS attacks include personal, financial, or political

Higher Computing full course Revision cards (3 decks)

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