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Comp Sci - Final Mocks - Coggle Diagram
Comp Sci - Final Mocks
1.1
FDE Cycle (managed by the control unit):
- Instructions are fetched from RAM / main memory.
- Instructions are decoded by the control unit.
- Instructions are executed.
- Program counter is incremented by one.
- Cycle repeats.
Common components:
- ALU: Performs and arithmetic operations or logic decisions within the CPU.
- CU: Governs the flow of data throughout the CPU using control signals.
- Cache: Stores commonly used data, instructions and parts of the OS. It is faster to access than the RAM because it uses static RAM.
- Registers: Small, temporary data stores with a very specific purpose.
Von Neumann Architecture:
- MAR: Holds the address of where data is to be fetched or stored.
- MDR: Holds any data that has just been fetched from memory or is to be written to memory.
- PC: Holds the address of the next instruction to be executed.
- ACC: Holds the result of any arithmetic operations or logic decisions.
1.2
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RAM:
- Volatile memory that stores currently used data, currently used instructions and currently used parts of the OS. It is read-write and its contents can be changed.
ROM:
- Small piece of non-volatile memory that contains the first instructions needed for a computer (bootstrap and BIOS). Contents can typically not change and it is read-only.
Virtual memory is used when the RAM is full; it is stored in secondary storage and is is very slow to run instructions on virtual memory so they must first be moved back into RAM. It stores not currently...
Secondary storage is needed to store data in a non-volatile manner (permanently). Secondary storage can change (is writeable) and stores an archive of data files.
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ASCII - 7 / 8 bit character set, does not account for foreign characters or emojis.
1.3
- Bandwidth - Amount of data that can be transferred at one time across the transmission media (measured in b/s / bit rate).
- Latency - Caused by bottlenecks in the infrastructure of the network. It is the delay between sending data and receiving it.
- Error rate - Number of packets in a given time that have to be resent. It is often caused by unreliable connections.
- Transmission media - Wired connections have a higher bandwidth than wireless connections.
- Number of users - Too many users or devices will cause the network to slow down if there is insufficient bandwidth.
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Hosting is the storing of files and data / a webpage on a web server, this server is known as a host and will often charge for usage. Benefits include 24/7 access, greater security and multiple users.
The Cloud:
- Access any time.
- Automatic backup.
- Easy online collaboration.
- Large storage capacity.
- Must have a Wi-Fi connection.
- Cloud is responsible for security.
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Protocols:
- TCP/IP: Routes data across WANs (between routers) in an error-free manner.
- HTPP: Allows for the sending or receiving of requests for HTML webpages.
- FTP: Allows for transfer of files between devices on a network.
- SMTP: Allows for sending of emails from a device to a mail server.
- POP: Used to retrieve emails from a mail server by removing it form the server.
- IMAP: Leaves the original copy of the email on the mail server.
1.4
Malware: Firewall, spam filter, updating OS, regularly backup files.
Phishing: Spam filter, staff training (how), implement strong network policies.
Brute force: Progressive delays, strong passwords (network policies), challenge response authentication.
DDoS: Strong firewalls, packet filters, network forensics, storing data on the cloud.
Data interception: Encryption, use of virtual networks, training staff.
1.6
Data Protection Act 2018:
- Data must be processed lawfully and in a transparent manner.
- Data must be collected for specified and legitimate reasons.
- Data must be relevant and limited.
- Data must be kept updated.
- Data should not be kept for longer than is necessary.
- Data must be kept and processed in a secure manner.
Computer Misuse Act 1990:
- Makes it illegal to make any unauthorised access to data with the intent to commit further offences: modify data, etc...
- Fraud.
- Planting of viruses.
- Hacking.
- Data theft.
- Deliberate data destruction.
Copyright Designs and Patents Acts 1998:
- Makes it illegal to copy any work without permission from the owner.
2
Arrays cannot be appended to and contain all of the same data type. Conversely, lists can be appended to and can contain a range of data types.
Assembly Language:
- Translated by an assembler into machine code.
- Works on one type of processor only.
- Code is harder to write and understand.
Compiler:
- Translates source code into from high-level languages into object code and then machine code.
- No need for translation software at runtime.
- Faster execution speeds.
- Code is usually optimised.
- Original source code is kept secret.
- Program will not run with syntax errors so it is harder to spot these errors.
- Code must be recompiled if a change is made.
Interpreter:
- Easier to code as syntax errors will be flagged up line by line during runtime.
- Translation software is needed at runtime.
- Code is not optimised.
- Source code is needed.
IDE Features:
- Allows for commenting and indentation.
- Runtime environment.
- Allows for manual stepping.
- Allows for variables to be monitored.
- Auto-completion.
- Syntax highlighting.