Unit 324 Stuff I Should Remember Flashcards
What are the Dedicated Registers? (5)
- Program Counter (PC)-
- Current Instructions Register (CIR)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Accumulator
What is the Fetch section of the FDE Cycle? (4)
- The address of the next instruction is copied from the PC to the Memory Address Register
- The instruction held at that address is copied to the Memory Data Register
- Simultaneously, the contents of the Program Counter (PC) are incremented
- The contents of the MDR are copied to the current Instruction Register
What is Parallel Processing?
Using several processor cores working at the same time is known as parallel or concurrent processing
What is Pipelining?
Improves performance by overlapping stages in the FDE cycle or by breaking down the stages in an arithmetic instructions
What happens in Von Neumann Architecture?
Instructions and data are stored in a common main memory and transferred using a single shared bus
What happens in Harvard Architecture?
A
Data and instructions are separated into separate memories using different buses
Q
How is Von Neumann and Harvard Architecture used in Desktop Computers?
There is one main memory for holding both data and instructions, but cache memory is divided into an instruction cache and a data cache so data and instructions are retrieved using Harvard architecture
What is CISC?
Complex Instruction Set Computers
A large instruction set is used to accomplish tasks in as few lines of assembly language as possible
What is RISC?
Reduced Instruction Set Computers
A minimum number of very simple instructions, each taking one clock cycle, are used to accomplish all the required operations in multiple general purpose registers
What is a GPU?
Graphics Processing Unit
A specialized electronic circuit which is very efficient at manipulating computer graphics and image processing
What are the features of a Hard Disk? (3)
- High capacity
- Relatively cheap storage per TB
- Fast read and write speeds
What are the features of Solid State? (6)
- Durable
- Less capacity than Hard Disk
- Faster than Hard Disk
- More portable
- Consumes less power
- More expensive than Hard Disk
What are the features of a USB? (4)
- Can store up to 128GB
- Cheap
- Can be password protected
- Useful for transferring data between computers
What functions does the OS provide? (4)
- User interface
- Memory management
- Interrupt handling
- Processor scheduling
What is Paging?
Available memory is divided into fixed chunks(pages). Each page has an address. Each running program in RAM is given sufficient pages but pages may not be contiguous
What is Segmentation?
Memory is divided into segments that can be different lengths. A particular function or subroutine occupies each segment
What is BIOS?
Basic Input Output System
Boots the computer at start-up. Stored in ROM
What is a Device Driver?
A program that provides an interface for the OS to interact with a device. Drivers are hardware dependent and OS specific
What is a Virtual Machine?
A compute resource that uses software instead of a physical computer to run programs and deploy apps
What are the different types of System Software? (4)
- Operating System
- Utilities
- Libraries
- Translators
What are the categories of Application Software? (3)
- General purpose
- Special purpose
- Bespoke
What is the difference between Off-The-Shelf Software and Bespoke Software?
Off-the-shelf software is ready made software available for anyone to purchase. Bespoke software is custom made
What criteria might you use when selecting an application to use? (5)
- Functionality
- Hardware
- Cost
- Availability
- Reliability
What are the features of a Compiler? (4)
- Programs can be run many times without needing compiling again
- Faster to execute
- Executable code does not require an interpreter to run
- Compiled code can not be easily read and copied by others
What are the features of an Interpreter? (2)
- Source code can be run on any machine with an interpreter
- If an error is found, code does not need to be fully compiled
What are the 5 five stages of Compilation?
-Lexical analysis - All unnecessary spaces and all comments removed. Keywords are replaced with tokens
- Symbol table - Symbol table with tokens is built up. Keeps track of the run-time memory address for each identifier
- Syntax analysis - The stream of tokens is split up into phrases. Each phrase is parsed. If the phrase isn’t valid, an error will be recorded
- Semantic analysis - The code is checked for errors that are logical not syntax
- Code generation - The compiler generates the machine code
What does Parsing mean?
When a phrase is checked against the rules of the language
What does the Loader do?
Copies the program and any linked subroutines into main memory to run
What is a Library?
Pre-written and pre-compiled functions. Can be written by a user and called within a program
What are the stages of Software Development? (5)
- Analysis
- Design
- Implementation
- Evaluation
- Maintenance
What happens in the Spiral Model?
Stages are looped repeatedly. Each loop generates a new prototype until software meets all requirements
What happens in the Waterfall Model?
Each stage is completed before the next one begins. The user doesn’t see the end product until it is completed. Any changes usually means the project has to be restarted
What happens in the Agile Model?
Software is developed in quick, small cycles. Each version adds more functionality and is tested before release. Good for small, quick projects. Less planning is needed to start
What are the Programming Paradigms? (4)
- Procedural
- Object-Orientated
- Declarative
- Functional
What is Imperative Programming?
A style of programming that consists of a series of instructions that tell the computer what to do with the input in order to solve the problem
What is Structural Programming?
A style of programming where programs are broken into different functions these functions are also known as modules, subprograms, subroutines and procedures
What is Declarative Programming?
A style of programming that uses statements to describes the program then finds the best way of solving it. It is used to create, amend and query databases
What is Logic Programming?
A form of declarative programming that expresses the logic of a computation without expressing its control flow. Programs consist of logical statements
What is Object-Orientated Programming?
A style of programming that makes it possible to abstract details of implementation away from the user
What are the 3 Branches in LMC?
- BRZ branch if 0
- BRP branch if 0 or positive
- BRA branch always
What is Run Length Encoding?
A basic method of coding that summarizes consecutive patterns of the same data
What is Dictionary Compression?
Spots regularly occurring data and stores it separately in a dictionary
What is Asymmetric Encryption?
A type of encryption that uses 2 keys. One key (public key) is made public so that others can encrypt data before sending it to you. Another key (private key) is only known to you and can be used to decrypt the data
What does ACID stand for? (4)
- Atomicity - Full or not at all
- Consistency - Meets guidelines
- Isolation - At the same = same as alone
- Durability - Stays done
What is Referential Integrity?
Where no foreign key can reference a record that doesn’t exist in another table
What is a TCP/IP Stack?
A set of rules used in turn, to format a message so it can be sent over a network. Each layer provides a specific function within the transmission of the message
What are the layers of a TCP/IP Stack? (4)
- Application layer
- Transport layer
- Internet layer
- Link layer
What is the Application Layer used for?
Providing services for applications that want to communicate across a network, often the Internet
How does the Transport Layer work? (4)
- Uses the Transmission Control Protocol (TCP) to establish an end‐to‐end connection with the recipient computer
- Splits data into packets and numbers them sequentially
- Adds port number to be used based on HTTP protocol
- At the receiving end this layer confirms that packets have been received and requests any missing packets be resent
How does the Internet Layer work? (3)
- Uses the Internet Protocol (IP) to address packets with the source and destination IP addresses
- A router forwards each packet towards an endpoint called a socket, defined by the combination of IP address and port number
- Each router uses a routing table to instruct the next hop
How does the Link Layer work?
- Operates across a physical connection
- Adds the MAC address of the physical NIC that packets should be sent to based on the destination IP address
- MAC addresses change with each hop
Using the TCP/IP Stack Levels, how is data received? (4)
- The Link Layer removes the MAC address from each packet and passes it to the Internet Layer
- The Internet Layer removes the IP address from each packet and passes it to the Transport Layer
- The Transport Layer removes the port number f from each packet, reassembles the packets in the correct order and passes them to the Application Layer
- The Application Layer presents the image data for the user in a browser
What are the features of Client-Server Networking? (6)
- A central server is used to manage security
- Some files are held on the central server
- Some processing tasks are performed by the server
- Clients issue requests to the server for services such as email, file storage, backup and printing
- Suitable for many different types of organization, small and large
- Can require specialist IT staff to administer the network
What are the features of Peer-to-Peer Networking? (5)
- Files and programs stored on individual computers
- Suitable for a home computer network
- Cheap to set up and maintain
- Each computer on the network can act as both client and server
- Can be used for sharing of music and streaming coverage of live events
What is the difference between HTML and CSS?
HTML is used to define the page content and structure
CSS are used to define page styles and appearance
What is the benefit of using External CSS Files?
Enables you to apply styles on a single CSS stylesheet to multiple HTML files throughout an entire website.
This also removes the CSS from the HTML pages making them easier to read
What is Javascript used for?
Used to program the behavior of web pages and add interactivity between the user and a web page
What is the Damping Factor?
The probability of a random web browser reaching a page. This value is usually set to 0.85
What Factors affect PageRank? (6)
- Domain name – relevance to the search item
- Frequency of search term in web page
- Age of web page
- Frequency of page updates
- Magnitude of content updates
- Keywords in <H1> tags
What year was the Data Protection Act made and what does it do?
1998
Controls the way data about living people is stored and processed
What year was the Computer Misuse Act made and what does it do?
1990
Makes it an offence to access or modify computer material without permission
What year was the Copyright, Designs and Patents Act made and what does it do?
1988
Covers the copying or use of other peoples’ work
What year was the Regulation of Investigatory Powers Act made and what does it do?
2000
Regulates surveillance and investigation, and covers the interception of communications
What are the properties of a Tuple? (3)
- It is an ordered set of values
- It may have elements of mixed types
- It is immutable
What are the 3 Tree Traversals?
- Pre-order Traversal - Left Dot
- In-order Traversal - Bottom Dot
