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GCS AQA computer science > Paper 2 > Flashcards

Paper 2 Flashcards

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1
Q

Four functions of an operating system:

A
  • Processor management
  • Memory management
  • Storage management
  • Network management
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2
Q

Low level language:

A
  1. Code is not translated using a compiler
  2. Code can directly manipulate computer registers
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3
Q

It is a program translator

Assembler:

A

Translates assembly language into machine code.

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4
Q

How does an interpreter work:

A
  • Interpreters don’t produce machine code, so the program needs to be translated each time it’s executed.
  • They call machine code subroutines withhin their own code to carry out their commands
  • Translates a line at a time, which it then executes
  • If a runtime error is found, the interpreter stops
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5
Q

Why do computers have more RAM than cache memory?

A
  • RAM is cheaper
  • Cache memory is not enough to store both data and programs
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6
Q

Two advantages of using cloud storage, rather than local storage:

A
  • Cloud storage is automatically backed up by the host
  • Allows user to access their data from more devices
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7
Q

Many new computers use solid-state storage for secondary storage rather than magnetic storage.

Explain why solid-state storage is not fitted to every new computer.

A
  • SSD’s are expensive
  • They have a lower capacity than magnetic hard drives
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8
Q

Sample resolution:

A

Number of bits per sample

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9
Q

Differences between a Local Area Network (LAN) and a Wide Area Network (WAN):

A
  • LAN’s and WAN’s use different protocols
  • WAN’s are slower than LAN’s
  • WAN’s have a larger number of users
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10
Q

Give three advantages of using a wireless network instead of a wired network:

A
  • Users can move around whilst using their device
  • Able to add users/devices to the network
  • No need to install cabling
  • BUT, BANDWITH IS LOWER THAN WIRED NETWORKS
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11
Q

System software:

A

Controls computer hardware

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12
Q

Application software:

A

Is for ending user tasks
e.g social media application or gaming software

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13
Q

Network protocols:

A

A set of rules for how devices communicate and how data is transmitted. Covers how communication between two devices should start and end.

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14
Q

Security measures:

A
  • Two-factor authentification, asks for a second form of identification
  • Biometrics- biometrics is unique to the individual, prevents hackers
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15
Q

Why might data be compressed?

A
  1. Reduces file size
  2. Uses less memory
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16
Q

Relational database

A

A database with multiple tables that are linked together.

ADVANTAGES- reduces data inconstistency
- Saves storage space

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17
Q

Foreign key:

A

A field that references the primary key in a different table.

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18
Q

What are the equations of file size?

A
  • File size (in bits)- image size * colour depth
  • File size (in bits)- Sample rate (Hz) * sample resolution * length (s)
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19
Q

Network protocol 1- the APPLICATION LAYER:

A

Sends web pages, using an encrypted connection(e.g. http/s).

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20
Q

Network protocols 2- the TRANSPORT LAYER:

A

Sets up communication between two devices, splits data into packets, checks if packets are correctly sent and delivered (e.g. TCP).

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21
Q

Network protocols 3- the INTERNET LAYER:

A

Adds IP adress to packets, directing them between devices. Used by routers (e.g. IP)

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22
Q

Network protocols 4- the LINK LAYER:

A

Passes data over the physical network. Responsible for how data is sent as electrical signals over cables (e.g. wifi)

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23
Q

Increase sampling rate- effects:

A
  • The file size would increase
  • The more samples means that the sound would be recoded at a higher quality
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24
Q

RAM

A
  • Is used for main memory
  • Is used for volatile memory
  • Temporary storage of instructions and data
  • Holds information being executed by the processor
  • Much faster than the hard disk
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25
Q

Factors that affect CPU performance- clock speed:

A

Clock speed:
* The more pulses per second, the more fetch-execute cycles
* Higher clock speed- more instructions can start per second

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26
Q

Factors that affect CPU performance- the number of processor cores:

A

Number of processor cores:
* Different processor cores deal with different types of instructions
* Each processor core can fetch it’s own instruction- increases the speed at which instructions can be executed.

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27
Q

Factors that affect CPU performance- Cache size:

A

Cache size:
* Instructions take less time to transfer to the processor from cache
* Because cache is held closer to the processor

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28
Q

Computer network:

A
  • Two or more computers
  • Connected together
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29
Q

How does two-factor authentification work?

A
  • Asks for a second piece of identification
  • Such as something you know
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30
Q

Data privacy concerns
(wireless network):

A
  • Malware infiltration- Wifi is more exposed to an attack because it is visible
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31
Q

ASCII

A

7 bits per character. Room for 2^7= 128 characters.
Disadvantages: Does not have enough characters for many languages.

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32
Q

Unicode

A

Represents thousands of characters.

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33
Q

Colour depth

A

Number of bits per pixel

34
Q

No. of colours

A

No. of colours= 2^colour depth

35
Q

Utility software:

A

Supports running of the computer system

36
Q

Operating software:

A

Manages hardware and other programs
E.g.:
* Processors
* Memory
* Input/output
* Applications
* Security

37
Q

Machine code:

A

The language the computer can directly execute

  • Easier to optimise
  • However, it is very specific to every CPU
  • Binary representation
  • Faster to execute
38
Q

High level language:

A
  • Like written english
  • More readable
  • Portable- can run on many CPUs
  • However, it is slower to execute
39
Q

Compilers:

A

Translate the high level language into machine code

  • Fast to execute
  • However, errors are only shown at the end
40
Q

Star topology:

A

Main computers connected to a central device.

  • Easy to add new devices
  • Decent level of security
  • However, you are reliant on central node
41
Q

Bus topology:

A

Computers connected by a central wire.

  • Simple and cheap to set up
  • Not dependant on a central server
  • Low performing- many collisions
42
Q

Fetch- execute cycle:

A
  1. Fetch- Next instruction is loaded from main memory
  2. Decode- Instruction is interpreted by CU.
  3. Instruction is carried out
43
Q

State two issues with only using usernames and passwords in an authentication
system.

A
  • Weak passwords are easily cracked
  • Usernames/passwords may appear in a data leak
44
Q

Why is run length encoding not a suitable method sometimes?

A
  • The data do not have a high frequency of consecutive repeating characters
  • The data will take up more storage than the original data
45
Q

Penetration testing:

A
  • The process of attempting to gain access to a computer system
  • Without the knowledge of usernames
46
Q

Aim of a white-box penetration test:

A

To stimulate an attack from an insider that has the knowledge of credentials to the targeted system.

47
Q

Primary storage:

A
  • With the exception of ROM all are volatile
  • ROM is considered read only
  • Relatively small capacity compared to secondary storage
  • Very fast access time compared to secondary storage
48
Q

ALU:

A

Responsible for carrying out:
* Arithmetic calculations
* Malking logical decisions

49
Q

CU:

A
  • Sends signals to control how data moves around the CPU
50
Q

Cache:

A
  • Provides fast access to frequently used data and instructions
51
Q

Clock:

A
  • The electronic unit that synchronises related components by generating pulses at a constant rate.
52
Q

Registers:

A
  • Tiny, superfast pieces of onboard memory inside the CPU
  • Each has a very specific purpose
53
Q

Buses:

A
  • Collection of wires through which data and instructions are transmitted from one component to another
54
Q

Definition of computer:

A
  • An electronic device which takes in an input, processes data and delivers an output
55
Q

Clock speed:

A
  • Measured in Hz
  • Number of cycles per second
  • Modern processors operate at billions of cycles per second
  • 3.2 billion instructions can be fetched per second (3.2 Ghz)
56
Q

Embedded system:

A
  • A computer system with a dedicated function within a larger mechanical system

TYPICAL PROPERTIES:
1. Low power consumption
2. Small size
3. Rugged operating ranges
4. Low cost per unit

EXAMPLES:
* Traffic lights
* Domestic appliances (washing machines)
* Hospital equipment

57
Q

Secondary storage:

A
  • All are non-volatile
  • Much larger storage capacity compared to primary storage
  • Very slow access times compared to primary storage
58
Q

ROM:

A
  • Small piece of read only memory located on the motherboard
  • Non-volatile
  • Contains very first instructions for the computer
59
Q

Why is secondary storage needed?

A

Secondary storage is needed because ROM is read only and RAM is volatile

Secondary storage is needed for:
* Storage for programs and data wwhen the computer is turned off
* Backup of data files
* Archive of data files

60
Q

Cloud storage:

A

Remote servers that store data that can be accessed over the internet
* Typically uses magnetic hard drives
* Use of SSD’s is increasingly popular

61
Q

Advantages of cloud storage:

A
  • Access your files anywhere, anytime or from any device
  • Automatic backup is possible
  • Files no longer take up any space on your own device
62
Q

Disadvantages of cloud storage:

A
  • Can be expensive, monthly or yearly subscriptions
  • No access to files without an internet connection
63
Q

Advantages of networking:

A
  • Users can share files
  • Communication with other people
  • Users can access their files from any computer on the network
64
Q

PAN:

A

PAN is any commputer which uses data transmission amongst very localised devices:

  • Cell phone
  • Tablet
  • Most common communication technology used in PAN is bluetooth
  • Very short range, 10 metres
65
Q

Disadvantages of networking:

A
  • Increased security risks to data
  • The computer may run more slowly if there is a lot of data travelling on the network
66
Q

What is a protocol?

A

A protcol is a set of rules that allow two devices to communicate

67
Q

Ethernet:

A

Family of related protocols, providing the basics of communication over a LAN.

68
Q

Wifi:

A
  • Family of related protocols providing the basics of wireless communication
69
Q

TCP:

A
  • Provides an error free transmission between two routers
70
Q

UDP:

A
  • Part of the internet protocol suite, used by programs running on different computers on a network
  • Used to send short messages called datagrams
71
Q

IP:

A
  • Routes packets accross a WAN
  • Along with TCP it makes up the TCP/IP stack.
72
Q

HTTP:

A
  • A client-server method of requesting and delivering HTML webpages
73
Q

Protocols for handling webpage requests- HTTPS:

A
  • Encryption and authentication for requesting and delivering HTML web pages
  • Used when sensetive information needs to be transferred e.g. passwords and bank account details
74
Q

FTP:

A
  • Used for sending files between computers, usually on a WAN
75
Q

Email protocols- SMTP:

A
  • Sends emails to an email server
76
Q

Email protocols- IMAP:

A
  • Used by mail clients to manage remote mail boxes
77
Q

Social engineering meaning:

A
  • The art of manipulating people, so they give up confidential information
78
Q

Maliciuos code:

A
  • Any software designed with the intent to cause damage, dsiruption or inconveience
  • E.g. virus, trojan, spyware
79
Q

Weak and default passwords:

A
  • People not changing their password, or using easy to guess/ short passwords
80
Q

Unpatched/ outdated software:

A
  • Out of date operating system that can have flaws which get exploited
81
Q

Misconfigured access rights:

A

GCS AQA computer science (2 decks)

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