Paper 2 Flashcards
Four functions of an operating system:
- Processor management
- Memory management
- Storage management
- Network management
Low level language:
- Code is not translated using a compiler
- Code can directly manipulate computer registers
It is a program translator
Assembler:
Translates assembly language into machine code.
How does an interpreter work:
- 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
Why do computers have more RAM than cache memory?
- RAM is cheaper
- Cache memory is not enough to store both data and programs
Two advantages of using cloud storage, rather than local storage:
- Cloud storage is automatically backed up by the host
- Allows user to access their data from more devices
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.
- SSD’s are expensive
- They have a lower capacity than magnetic hard drives
Sample resolution:
Number of bits per sample
Differences between a Local Area Network (LAN) and a Wide Area Network (WAN):
- LAN’s and WAN’s use different protocols
- WAN’s are slower than LAN’s
- WAN’s have a larger number of users
Give three advantages of using a wireless network instead of a wired network:
- 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
System software:
Controls computer hardware
Application software:
Is for ending user tasks
e.g social media application or gaming software
Network protocols:
A set of rules for how devices communicate and how data is transmitted. Covers how communication between two devices should start and end.
Security measures:
- Two-factor authentification, asks for a second form of identification
- Biometrics- biometrics is unique to the individual, prevents hackers
Why might data be compressed?
- Reduces file size
- Uses less memory
Relational database
A database with multiple tables that are linked together.
ADVANTAGES- reduces data inconstistency
- Saves storage space
Foreign key:
A field that references the primary key in a different table.
What are the equations of file size?
- File size (in bits)- image size * colour depth
- File size (in bits)- Sample rate (Hz) * sample resolution * length (s)
Network protocol 1- the APPLICATION LAYER:
Sends web pages, using an encrypted connection(e.g. http/s).
Network protocols 2- the TRANSPORT LAYER:
Sets up communication between two devices, splits data into packets, checks if packets are correctly sent and delivered (e.g. TCP).
Network protocols 3- the INTERNET LAYER:
Adds IP adress to packets, directing them between devices. Used by routers (e.g. IP)
Network protocols 4- the LINK LAYER:
Passes data over the physical network. Responsible for how data is sent as electrical signals over cables (e.g. wifi)
Increase sampling rate- effects:
- The file size would increase
- The more samples means that the sound would be recoded at a higher quality
RAM
- 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
Factors that affect CPU performance- clock speed:
Clock speed:
* The more pulses per second, the more fetch-execute cycles
* Higher clock speed- more instructions can start per second
Factors that affect CPU performance- the number of processor cores:
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.
Factors that affect CPU performance- Cache size:
Cache size:
* Instructions take less time to transfer to the processor from cache
* Because cache is held closer to the processor
Computer network:
- Two or more computers
- Connected together
How does two-factor authentification work?
- Asks for a second piece of identification
- Such as something you know
Data privacy concerns
(wireless network):
- Malware infiltration- Wifi is more exposed to an attack because it is visible
ASCII
7 bits per character. Room for 2^7= 128 characters.
Disadvantages: Does not have enough characters for many languages.
Unicode
Represents thousands of characters.
Colour depth
Number of bits per pixel
No. of colours
No. of colours= 2^colour depth
Utility software:
Supports running of the computer system
Operating software:
Manages hardware and other programs
E.g.:
* Processors
* Memory
* Input/output
* Applications
* Security
Machine code:
The language the computer can directly execute
- Easier to optimise
- However, it is very specific to every CPU
- Binary representation
- Faster to execute
High level language:
- Like written english
- More readable
- Portable- can run on many CPUs
- However, it is slower to execute
Compilers:
Translate the high level language into machine code
- Fast to execute
- However, errors are only shown at the end
Star topology:
Main computers connected to a central device.
- Easy to add new devices
- Decent level of security
- However, you are reliant on central node
Bus topology:
Computers connected by a central wire.
- Simple and cheap to set up
- Not dependant on a central server
- Low performing- many collisions
Fetch- execute cycle:
- Fetch- Next instruction is loaded from main memory
- Decode- Instruction is interpreted by CU.
- Instruction is carried out
State two issues with only using usernames and passwords in an authentication
system.
- Weak passwords are easily cracked
- Usernames/passwords may appear in a data leak
Why is run length encoding not a suitable method sometimes?
- The data do not have a high frequency of consecutive repeating characters
- The data will take up more storage than the original data
Penetration testing:
- The process of attempting to gain access to a computer system
- Without the knowledge of usernames
Aim of a white-box penetration test:
To stimulate an attack from an insider that has the knowledge of credentials to the targeted system.
Primary storage:
- 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
ALU:
Responsible for carrying out:
* Arithmetic calculations
* Malking logical decisions
CU:
- Sends signals to control how data moves around the CPU
Cache:
- Provides fast access to frequently used data and instructions
Clock:
- The electronic unit that synchronises related components by generating pulses at a constant rate.
Registers:
- Tiny, superfast pieces of onboard memory inside the CPU
- Each has a very specific purpose
Buses:
- Collection of wires through which data and instructions are transmitted from one component to another
Definition of computer:
- An electronic device which takes in an input, processes data and delivers an output
Clock speed:
- 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)
Embedded system:
- 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
Secondary storage:
- All are non-volatile
- Much larger storage capacity compared to primary storage
- Very slow access times compared to primary storage
ROM:
- Small piece of read only memory located on the motherboard
- Non-volatile
- Contains very first instructions for the computer
Why is secondary storage needed?
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
Cloud storage:
Remote servers that store data that can be accessed over the internet
* Typically uses magnetic hard drives
* Use of SSD’s is increasingly popular
Advantages of cloud storage:
- Access your files anywhere, anytime or from any device
- Automatic backup is possible
- Files no longer take up any space on your own device
Disadvantages of cloud storage:
- Can be expensive, monthly or yearly subscriptions
- No access to files without an internet connection
Advantages of networking:
- Users can share files
- Communication with other people
- Users can access their files from any computer on the network
PAN:
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
Disadvantages of networking:
- Increased security risks to data
- The computer may run more slowly if there is a lot of data travelling on the network
What is a protocol?
A protcol is a set of rules that allow two devices to communicate
Ethernet:
Family of related protocols, providing the basics of communication over a LAN.
Wifi:
- Family of related protocols providing the basics of wireless communication
TCP:
- Provides an error free transmission between two routers
UDP:
- Part of the internet protocol suite, used by programs running on different computers on a network
- Used to send short messages called datagrams
IP:
- Routes packets accross a WAN
- Along with TCP it makes up the TCP/IP stack.
HTTP:
- A client-server method of requesting and delivering HTML webpages
Protocols for handling webpage requests- HTTPS:
- 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
FTP:
- Used for sending files between computers, usually on a WAN
Email protocols- SMTP:
- Sends emails to an email server
Email protocols- IMAP:
- Used by mail clients to manage remote mail boxes
Social engineering meaning:
- The art of manipulating people, so they give up confidential information
Maliciuos code:
- Any software designed with the intent to cause damage, dsiruption or inconveience
- E.g. virus, trojan, spyware
Weak and default passwords:
- People not changing their password, or using easy to guess/ short passwords
Unpatched/ outdated software:
- Out of date operating system that can have flaws which get exploited
Misconfigured access rights:
