OCR GCSE Computer Science Paper 1 - Computer Systems - Comprehensive Notes

Central Processing Unit (CPU)

• Purpose: Process data instructions using the fetch-execute cycle.

• Fetch-Execute Cycle:

  • Instructions fetched from RAM.

  • Transferred into CPU registers (specifically the Memory Data Register).

  • Execute Stage:

    • Instructions decoded by the Control Unit.

    • Executed.

    • ALU performs arithmetic/logical calculations.

CPU Components

• Control Unit:

  • Sends control and timing signals to ALU and RAM.

  • Directs CPU operation.

  • Manages data flow and decodes instructions.

• Arithmetic Logic Unit (ALU):

  • Performs mathematical calculations, logical operations, and binary shifts.

• Registers:

  • Temporary storage for one piece of data or address.

  • Used in the fetch-execute cycle.

• Cache Memory:

  • Temporarily stores frequently accessed data.

  • Split into three levels (L1, L2, L3).

  • Faster access than RAM.

Registers in Detail

• Program Counter (PC):

  • Stores the address of the next instruction to be fetched from RAM.

  • Address copied to the Memory Address Register (MAR).

  • Incremented by one after copying, pointing to the subsequent instruction.

• Memory Address Register (MAR):

  • Stores the address of the current instruction to be fetched.

  • Receives address from the Program Counter.

• Memory Data Register (MDR):

  • Stores the instruction or data fetched from RAM, as identified by the MAR.

• Accumulator (ACC):

  • Stores results of executions (e.g., ALU calculations).

Register Usage in Fetch-Execute Cycle

• Fetch Stage:

  • Program Counter (PC) stores the address.

  • Memory Address Register (MAR) stores an address.

  • Memory Data Register (MDR) stores data.

• Execute Stage:

  • Accumulator (ACC) stores data.

Von Neumann Architecture

• Key Feature: Data and program instructions stored in the same format (binary) and memory (RAM).

• Utilizes standard CPU components: Control Unit, ALU, Registers, Cache, MAR, MDR, PC, ACC.

Instruction Structure

• Instructions split into two parts:

  • Opcode: Action to perform (e.g., add, input, load).

  • Operand: Refers to data (value) or address (RAM location).

Clock Speed

• Measure of how many fetch-execute cycles a CPU can perform per second.

• Measured in gigahertz (GHz).

• 1 \text{ GHz} = 1,000,000,000 \text{ cycles per second}

• Typical desktop CPU: 3-5 GHz.

• CPUs can be overclocked/underclocked.

Impact of Clock Speed

• Higher clock speed improves performance.

• More instructions processed per second.

• Faster completion of complex tasks.

Cache Memory (Revisited)

• Temporary storage for frequently accessed data.

• Split into three levels (L1, L2, L3) – each larger but slower than the previous.

• Reduces time by storing frequently required data, avoiding repeated RAM transfers.

• Larger cache size improves performance.

CPU Cores

• Core: Complete set of CPU components (Control Unit, ALU, Registers, L1 Cache).

• Each core performs its own fetch-execute cycle.

• Multi-core CPUs can process more instructions simultaneously.

• Performance Limitations:

  • Task dependencies between cores.

  • Older software not optimized for multi-core CPUs.

Embedded Systems

• Built into larger devices (e.g., cars, microwaves) for control.

• Limited functions, specific repeated tasks.

• Often use a microprocessor on a single circuit board.

• Firmware: Operating system and software built into ROM.

Examples of Embedded Systems

• Washing machine: Manages wash cycles and water temperature.

• Modern cars: Manages engine systems or automates lights.

Primary Storage

• High-speed internal memory directly accessible by the CPU.

• Types: RAM and ROM.

• Stores active data for high-speed fetching and execution.

• Limited capacity compared to secondary storage.

• Typical Sizes: ROM (MB), RAM (GB), Hard Drives (TB).

Random Access Memory (RAM)

• Volatile: Data lost when power is off.

• Temporarily stores instructions and data for running programs.

• Stores parts of the operating system.

• Contents can be changed (read and written).

Read-Only Memory (ROM)

• Non-volatile: Data saved even when power is off.

• Stores startup instructions (bootstrap program) to load the operating system.

• Stores BIOS (Basic Input/Output System) to check component functionality.

• Read-only: Contents cannot be changed.

• Programs stored in ROM are called firmware.

Virtual Memory

• Hard drive/SSD used as an extension to RAM when RAM is full.

• Inactive parts of programs moved to virtual memory.

• Pages moved back to RAM when needed.

• Allows more programs to run simultaneously without memory exhaustion.

• Excessive use causes disk thrashing and slowdowns.

Secondary Storage

• Long-term storage of files and data (non-volatile).

• Higher capacity than primary storage (up to several TB).

• Types: Magnetic, Optical, and Solid State.

Characteristics of Secondary Storage

• Mnemonic: CSNUS (PC Card)

  • Portability: Ease of moving the device.

  • Capacity: Maximum amount of data stored (GB/TB).

  • Price: Cost per gigabyte.

  • Access Speed: How quickly data can be read/written.

  • Reliability: How long the device lasts without failure.

  • Durability: Physical strength of the device during transport.

Optical Storage

• Becoming obsolete due to inferior characteristics.

• Types: CDs, DVDs, Blu-ray Discs.

• Low Capacities:

  • CD: 700 MB

  • DVD: 4.7 GB

  • Blu-ray: 25 GB

• Advantages: Cheap to manufacture, lightweight, portable.

• Disadvantages: Expensive per GB, low capacity, slow access speed (laser and spinning disc), easily scratched.

Magnetic Storage

• Popular for high capacity and low cost per GB.

• Common Type: Hard Disk Drive (HDD).

• Read/write head moves across magnetized spinning disk.

• Can be internal or external.

• Older Types: Magnetic tape (backup), floppy disks (obsolete).

• Large capacity (several TB).

• Cheapest per GB.

• Slower access speed than SSD.

• Less reliable and durable due to moving parts.

Solid State Storage

• Becoming very popular due to its superior characteristics.

• Types: Solid State Drives (SSD), USB Sticks, SD Cards.

• No moving parts: Data is directly accessed at high speed.

• Internal or external SSDs, portable USB sticks, SD cards in cameras/smartphones.

• Fastest access speed.

• Small, highly portable, reliable, and durable.

• Becoming cheaper, but still more expensive per GB than HDDs.

Binary Representation

• All data is stored in binary.

• Computer systems use transistors as switches (on=1, off=0).

• Bit: Single binary digit.

• Nibble: Four bits.

• Byte: Eight bits.

Data Storage Units

• Difference of 1,000 between units (e.g., 1,000 bytes = 1 KB).

• Alternate system uses 1,024 (kibibytes, mebibytes, etc) – usable in exams, but calculations without a calculator simpler using 1,000.

Data Size Examples

• Character: 1-2 bytes.

• Text documents (e.g., Kindle books): Kilobytes.

• Songs and Images: Megabytes.

• Software (e.g., video games): Gigabytes.

• Movies: Gigabytes.

• Secondary Storage (HDD/SSD): Terabytes.

• Global Organizations (Google, Meta, Microsoft): Petabytes.

• 1 \text{ PB} \approx 250,000,000 \text{ images} \approx 1,000,000 \text{ hours of video}

Calculating Storage Requirements

• File size and capacity must use the same units.

• Conversion:

  • Larger to smaller unit: multiply by 1,000.

  • Smaller to larger unit: Divide by 1,000.

Example Calculations

• Josh has 500 MB, images are 650 KB. Images can be stored:

  • 500 \text{ MB} \times 1,000 = 500,000 \text{ KB}

  • 500,000 \text{ KB} / 650 \text{ KB} \approx 769 \text{ images}

Multiple Unit Conversions

• Convert 340,000 KB to GB:

  • 340,000 \text{ KB} / 1,000 = 340 \text{ MB}

  • 340 \text{ MB} / 1,000 = 0.34 \text{ GB}

Number Systems

• All data stored in binary due to transistors acting as switches (on=1, off=0).

Number System Base

• Base: Number of unique digits.

• Binary: Base-2 (0 and 1).

• Denary (Decimal): Base-10 (0-9).

• Hexadecimal: Base-16 (0-9, A-F).

Binary Details

• Each place is a power of two.

• Least Significant Bit (LSB): Rightmost bit, represents one.

• Most Significant Bit (MSB): Leftmost bit, represents the largest value (e.g., 128 in an 8-bit number).

Hexadecimal Details

• Each digit represents four bits (a nibble).

• A=10, B=11, C=12, D=13, E=14, F=15

• Easier to read/write binary, lower chance of mistakes.

• Example: 8C9E (4 digits) vs. binary equivalent (16 digits).

Number System Summary

• Binary: 2 digits (0, 1); 8-bit range: 00000000 to 11111111.

• Denary: 10 digits (0-9); 8-bit range: 0 to 255.

• Hexadecimal: 16 digits (0-9, A-F); range: 0 to FF.

Bits and Denary Values

• 1 bit: 2 values (0, 1).

• 2 bits: 4 values (0, 3).

• Lowest denary value: always 0.

• Highest denary value: total values - 1.

• 8 bits: 256 values (0 to 255).

Binary to Denary Conversion

• Write out the binary number.

• Write binary place values (1, 2, 4, 8, 16, 32, 64, 128) from right to left.

• Add place values with a one beneath. Example:
  10110110 = 128 + 32 + 16 + 4 + 2 = 182

Denary to Binary Conversion

• Write binary place values from right to left.

• Check if place value fits into the denary number (from left to right).

• If it fits: write a one and subtract the value.

• If it doesn't fit: write a zero.

• Example: Convert 91 to Binary

Binary to Hexadecimal Conversion

• Hexadecimal digits (0-9, A-F) work with nibbles (groups of four bits).

• Write place values from right to left (1, 2, 4, 8).

• Calculate hexadecimal value of each nibble by adding place values with a one beneath.

Hexadecimal to Binary Conversion

• Hexadecimal digits (0-9, A-F) work with nibbles (groups of four bits).

• Write place values from right to left (1, 2, 4, 8).

• For each hexadecimal digit, convert to its 4-bit binary equivalent

Denary to Hexadecimal Conversion

• Easier to convert to binary first, using methods described earlier.

• Alternative method:

  • Uses integer division and modulo division.
    \text{Left Nibble = Denary Number} \div 16
    \text{Right Nibble = Denary Number} \mod 16

Hexadecimal to Denary Conversion

• Traditional method: Convert to binary first.

• Alternative method: Multiply the left nibble by 16, then add the value of the right nibble.

• Example: 7E = (7*16) + 14 = 126

Binary Addition

• Basic combinations:

  • 0 + 0 = 0

  • 1 + 0 = 1

  • 0 + 1 = 1

  • 1 + 1 = 10 \text{ (carry the 1)}

  • 1 + 1 + 1 = 11 \text{ (carry the 1)}

• Work from right to left, indicating 'carries'.

Overflow Errors

• Occurs when the result exceeds the maximum value that can be stored in the number of bits.

• For an 8-bit value, this is anything larger than 255.

• Will occur if there's a carry on the calculation of the most significant bit.

• Produce an incorrect result.

Binary Shifts

• Multiply or divide binary numbers by multiples of two.

• Left shift: Multiplies the number.

• Right shift: Divides the number.

• Effect doubles for every place shifted.

• Example: shifting 21 (00010101):

  • 1 place left (multiply by 2): 42 (00101010).

Binary Right Shift Example

Shifting 11010100 two places to the right divides by four.
*Zeros are written in any new spaces that have been created by the shift.

Effects of Binary Shifts

• Overflow Error (Left Shift):

  • Result exceeds maximum value (255 for 8-bit).

  • Shifting left with a one in the most significant bit will cause an overflow error.

  • Example: Shifting 181 one place to the left. This should have given 362, but an overflow error has occurred resulting in an answer of 106.

• Loss of Precision (Right Shift):

  • Dividing odd numbers results in decimal values, which standard bytes cannot store.

  • Shifting right with a one in the least significant bit will give an inaccurate result.

  • Example: Shifting 51 one place to the right, which should divide the number by two and give 25.5. However, the result is shown as 25 with a loss of precision of 0.5.

Character Sets

• Collection of all characters a computer can represent.

• Table maps each character to a unique binary code.

• Essential for exchanging data and inputting text.

• Characters include letters, numbers, symbols, control characters, and emojis.

Character Set: ASCII

• American Standard Code for Information Interchange.

• Uses one byte (8 bits) per character.

• Represents 256 different characters.

• Advantage: Uses less memory space.

• Disadvantage: Limited character range (256).

Character Set: Unicode

• Uses two bytes (16 bits) per character.

• Represents 65,536 possible characters.

• Advantage: Represents many more characters (all languages, symbols, emojis).

• Disadvantage: Requires more memory to store each character.

• Backwards compatible with ASCII (first 128 values match).

File Size of Text Files

• Calculated by: bits per character * number of characters.

• ASCII: 8 bits per character.

• Unicode: 16 bits per character.

Calculating Text File Size: Unicode

A text file uses the Unicode character set and contains 335 characters. What is the file size in bytes?

• Unicode uses 16 bits per character. So 16 multiplied by the number of characters, which is 335 to give 5,680 bits.

• Divide this by eight to give your answer in bytes, is 710.

Image Files: Bitmaps

• Most computer images are bitmaps.

• Use a series of square blocks called pixels arranged in a grid.

• Vectors use mathematical instructions instead of pixels.

Resolution

• Total number of pixels in an image (width * height).

• Affects image quality and file size (higher resolution = better quality, larger file size).

Color Depth

• Number of bits used to represent each pixel's color.

• Color depth of four = four bits, giving 16 possible colors.

• Larger color depth improves image quality but increases file size.

Metadata

• Additional data providing context about a file.

• For images: height, width, color depth, resolution, geolocation, date created/edited, file type, file name, etc.

Calculating Image File Size

• Resolution * color depth.

• An image has a width of 120 pixels and a height of two ten pixels. It has a color depth of six bits. What's the file size in kilobytes?
  First, work out the resolution by multiplying the width and height of the image in pixels. That's 120 times by 210 to give 25,200.
  Now we can multiply that number by the color depth, which is six bits, to give 151,200 bits.

Audio Files

• Analog sound waves are digitally recorded and stored in binary.

• Sampling: Measuring and recording the amplitude of the analog sound wave at specific intervals.

Sample Rate

• How many times per second the amplitude is measured.

• Measured in hertz (Hz).

• Standard rate: 44.1 kHz (CDs, Spotify).

• Higher sample rate increases audio quality but also increases file size.

Bit Depth

• The number of bits available to represent each sample.

• Represents the range of amplitude values available for each sample.

• Doubling the range with each bit added to the depth.

• One bit gives two possible amplitudes, two bits four possible amplitudes.

• Higher bit depth improves audio quality, but increases file size.

Audio File Size Calculation

• Sample rate * bit depth * duration.

• A sound file has a sample rate of 40 hertz and a bit depth of six bits. It lasts for twelve seconds. Give the answer in kilobytes.
  40 multiplied by six gives 240 bits per second.
  Multiplying 240 by the twelve seconds gives 2,880 for the whole sound file in bits.
  To convert from bits to bytes, you divide by eight. Two thousand eight hundred and 80 divided by eight gives 360 bytes. To convert from bytes to kilobytes, it's a division of 1,000. Three hundred and 60 bytes divided by 1,000 gives a final answer of 0.36 kilobytes.

Compression

• Using algorithms to reduce file size.

• Benefits: Less storage space, faster transfers, bypass file size limits, faster web loading.

Lossy Compression

• Permanently removes data, cannot fully restore original file.

• May result in a noticeable loss of quality.

• Can reduce image file size by decreasing color depth and resolution.

• An audio file can be compressed by removing very high or low frequencies that humans cannot hear.

• Smaller file sizes, faster transfers, works well for media files.

• Unsuitable for text or software files.

Lossless Compression

• Reduces file size without permanently removing data.

• File returns to original form when decompressed, no quality loss.

• There is no permanent loss of data, so the original file is fully restored. It can be recompressed any number of times without any reduction in quality.

• Lossless compression is essential for files that would be incomprehensible if data was permanently removed, such as text files and software like video games. A disadvantage of lossless compression is that as there is no permanent reduction of data, files will be larger in size than if lossy compression was used.
  *Files will be larger than with lossy compression and take longer to compress/decompress.

Networks

• Sets of computers connected to share data and resources.

• Can be wired or wireless.

Local Area Network (LAN)

• Connects computer systems geographically close together.

• Usually within the same building.

• Infrastructure is privately owned and managed.

• Faster data transfer speeds because there is a smaller distance for the data to travel.

Wide Area Network (WAN)

• Connects computer systems geographically distant to each other.

• Possibly across a country or even the entire world.

• The Internet is an example of a wide area network.

• Infrastructure is often not managed by a single group.

• Data transfer speeds are often slower because data transfer speed relies on the distance the data needs to travel.

Network Performance Issues

• Bandwidth: amount of data that can be transmitted per second - A higher bandwidth improves network performance as more data can be sent at once.

• Number of users or devices - Higher numbers of users or devices sharing the same network can slow down transfer speeds due to congestion* Wireless interference/obstacles, wired electromagnetic interference, large data transfers, poor signal strength, data collisions -

• Latency: the delay in the transmission of data - A lower latency improves responsiveness, and it is measured in milliseconds.

• Collisions: When packets of data are sent at the exact same time along the same connection, they may collide- The more data collisions on a network, the slower it will perform as the data will need to be resent.

• Weak server - A web server may perform poorly if it is overloaded by too many requests, maybe from a large number of users or maybe from a DDoS attack. The server may also have limited resources, such as a low CPU speed or little RAM.

Servers on the Internet

• Web Servers: Display web pages to the client when their browser requests it.

• File Servers: Store files and allow clients to retrieve them when requested.

• Printer Servers: Queue print jobs that clients request and send documents to the correct printer.

• Email Servers: Filter spam and send and store emails so they can be retrieved by clients when requested.

Web Hosting

• Websites and files must be stored on a web server to be accessible on the Internet.

• A domain name must be registered and added to the Domain Name System (DNS), which maps it to an IP address.

Client-Server Networks

• Clients request data or resources from a central server.

• Server processes request and returns a response.

• Advantages: data, security, and updates can be managed from a single location - Scalable by connecting more clients or upgrading the server. Data, security, and updates from asingle location making administration and backup easier.

• Central servers have powerful systems that can process many requests simultaneously. Disadvantages: Installing and managing a server is an expensive process; skilled IT staff may be required - If the server fails, clients cannot access any of its resources.

Peer-to-Peer Networks

• No central server; each computer is equal.

• Computers communicate directly.

• Often used in small offices or homes.

• Advantages: Simpler and less expensive to set up- easy directly sharing files between systems, other systems are not dependent on a specific server.

• Disadvantages: Central management of security and files access and backup, performance may be slower, difficult managing networks.

Network Devices

• Wireless Access Point: Provides a link between wired and wireless networks - creates a wireless local area network using radio waves that allows Wi Fi enabled devices to connect to a wired network

• Router: directs data packets between different networks- Routers receive data packets and use a routing table containing IP addresses to determine the best route to forward the packets on.

  • Switch: Connects devices on a LAN-It receives data packets from a connected system and forwards it directly to the correct device using its unique MAC address. MAC addresses of devices connected to the switch are stored in a table.

• Network Interface Controller (NIC): Hardware required to connect to a network.

Transmission Media

• Physical or wireless methods used to transfer data between devices.

Domain Name System (DNS)

• Uses servers to match domain names to IP addresses.

• Process:

  1. A request is sent to the local DNS server for the corresponding IP address of the domain name.

  2. The server has a list of domain names and their matching IP addresses.

  3. The DNS server checks if it holds an IP address corresponding to that domain name. If it does, it passes the IP address to the web browser.

  4. The browser connects to the IP address of a web server storing the web page to access and display it.

Cloud Computing

• Network of servers accessed on the Internet to provide services.

• Remote service provision: running applications, processing and storing data are done online in a different physical location for the user.

• Advantages: Data can be accessed from any device with a stable internet connection, multiple users can collaborate, automated backups and disaster recovery tools, Storage capacity is scalable, meaning it can be easily increased or decreased as needed, less need for alot of local storage - automatic software updates.

• Disadvantages: Requiring astable internet connection, possible slow upload/download speeds for large files - subscription fees - data is stored to a third party server leading to a data breach - transfer of data across network increasing the risk of internetion- data lost in a server fault.

Network Topology- layout of computer systems on a network.

*Star network topology- has all nodes connected to a central switch with data sent via the unique MAC address-
*Advantages- transmissions are monitored. Adding new nodes to the networks is easier - network is reliable.
*Disadvantages- Extra hardware is required- the whole network is unusable if the switch fails.

*Mesh Network Topology- Nodes are connected to all or most other nodes - data transferred using the quickest path possible; one node failing will not affect the rest of the network.
*Advantages- reliable due to multiple node connections. Direct data transfer reduces delay.
*Disadvantages- expensive to install - wired mesh topology are difficult to manage.

Wired Networks

• Transfer data across a physical connection using transmission media such as Ethernet cables.

• Ethernet cables used on local area networks to transfer data at high speeds up to 10 gigabits per second over short distance.
  *Advantages- faster data transfer- less delay with data - connection is more stable- security is better.
  *Disadvantages- limited movement restricted to cables- set up can be time consuming- additional costs required fo the network to function.

Wireless

Radio waves to transmit data through the air, two common wireless connection modes are Wi Fi and Bluetooth. Allows users to move freely within the coverage area without being restricted by cables- is convenient easy to set up new devices, even in outdoor locations. The wireless network may suffer with lower data transfer speeds leading to a much greater response time- easily intercepted and interfered therefore security issues can occur.

Encryption

• Process of scrambling data into unreadable format.

• Protects data if intercepted during transmission.

• Plaintext converted to ciphertext using an encryption key.

• Decryption key converts ciphertext back to plaintext.

• Used with all types of data, especially usernames and passwords.

IP Addresses- identifies a device's logical location on a network.

• IPv4 - uses 32 bit addresses allowing for just under 4,300,000,000 unique IP addresses.
  *IPV6-uses 128 bit addresses allowing for 340 undecillion possible addresses.

MAC Address

• Unique physical address assigned to each device's network interface controller.

• Used by Switches to identify and communicate with devices on a LAN.

• A 48 bit address made up of six eight-bit hexadecimal pairs from zero zero to f f, each of these separated by dashes or sometimes colons.

Protocols- a set of rules that allow computers to communicate and exchange data with each other across networks such as the Internet.

Network rules, such as protocols, must be standardized across all devices on a network to ensure they follow the same rules and interpret data and signals in the same way, regardless of a manufacturer.

• TCP-IP = reliably exchanges data between devices on the Internet.
  *HTTP is used to request and access a web page from a web server.
  *HTTPS - secures version using encryption which protects againist data interception.
  *FTP- Used to transfers files across a network mainly uploading and downloading between clients.
  *SMTP- Is used to send Emails to email servers and between email servers.
  *POP- Used to retrieve and store emails from an email server onto a computer.
  IMAP- Also retrieves and stores emails from an email server to a computer using the same funtion but saves the emails on synchronised so that they can be accessed by more devices.

Protocol Layers

• Each layer has a specific function - making it easier to develop and to update that layer affecting the protocol.
  *Each layer is self contained, meaning a developer can take a layer out and edit it without affecting other layers.

Malware

• Software with malicious intent.

• Examples: Viruses, Worms, Trojans, Spyware, Keyloggers, Ransomware, Rootkits, Adware.

• Protection: Anti-malware software, firewalls, user access levels.

Social Engineering- trcking victims into giving personal data or access to systems by pretending to be somebody they know.

*Protection= spam filters can protect phising links- A firewall can blcok a malicious URL from being opened- it's impoetant that personnel know that staff know that the signs of a phishsing scam
Strong network protection- Automated software may be used to try all combinations, starting with common passwords using a brute force attacks. - acount lockouts and two factor authentication can be used to better protect the server- Two factor authentication may be used requiring a password and a separate code.

Denial of Service (DoS) Attack- floods a web server with a large volume of traffic simultaneously overloading and causing it to fail. distributed form is called a DDoS attacks.

To better protect- The server may be protected with a fire wall can filter out malicious traffic to prevent the server from being overloaded. - also load balancers can distribute traffic across multiple servers.
A proxy server can filter malicious traffic and hide the server's IP address.

SQL Injection-hen a malicious query is entered into a websites input box.

To Protect- imput sanitization can be used to spot and SQL commands- User access levels should limit privileges to minimize potential damage- Penertation testing can identify insecure websites so they can be better protected.

Penetration Testing

• Assesses the security of a system or network.

• Identifies vulnerabilties for hacking.
  *Antiviral software scans files and programs and compares each to a database of known malware signatures.
  *This scan prevent suspcious files from impacting systems. Prevents all types of mayware for an attack.

Firewalls

*Monitors incoming and outgoing network traffic. Acts of as a barrier between two externalnetworks blocking unauthorised acess.

• This has a high prevention method which protects against malware and a D0S/DDoS attack. 


Strong Passwords- important to remember for the safety of a system and helps to pevent unithorised acess to data- protects against data theft.

Encyption = data is formatted into an unreadable state in the form of physical security.

Operating System (OS)

• Manages computer resources, memory, peripherals, users, files.

• Provides the user interface (GUI or command prompt).

• Manages Memory: ensures each program has enough space to run without intefering with other processes.

• ensures data is moved from the RAM for accessibility.
  It also enables multitasking by tracking active programs.The operating system manages how data is transferred between peripherals by setting a device driver and user access for certain features
  User Acces = user account permmission.

• Files by allowing them to be named, moved, copied, deleted, allocated to a folder, open, saved.

Utility Software

• Performs specific tasks related to maintenance and optimization.

• Examples: Anti-malware, firewall, backup, device drivers, encryption, defragmentation, compression.
  -Over time files on a hard drive will be split and stored in seperate locations of the disk
  *Defragmentation Software = Reorders files so that each part is stored consecutively improving data acess speeds. - compression is the use of an algorithm that reduce the site of a file.
  *comprresed filles take up less storage space so there can be more more file