What are the two types of Compression?Lossy and Lossless
What is Lossy Compression?Permanently removing non-essential data like different shades of a colour in an image.
What is Lossless Compression?Spotting patterns in data and shortening them, compressing the data but being able to restore it if needed.
What is Run Length Encoding (RLE)?A method of compressions turning patterns of data into one piece of data.
What is Dictionary Compression?Spotting regular occuring data and storing it in a dictionary to refer back to.
What is encryption?Making sure data cannot be understood for anyone not the sender / reciever.
What is the Caesar Cipher?Basic encryption, moving the letters of the data by a certain amount.
What is a Brute Force attack?Attempting to try every key until one decrypts the data.
What is the vernam cipher?Uncrackable encyption, using a one-time pad that must be truly random and has to be shared with reciever by hand without the data involved.
What is the XOR gate?Outputs true when only one of the inputs is true.
How do you decrypt the vernam cipher?Use a XOR operation on the message with the key.
What is symmetric encryption?Using the same key to encrypt and decrypt data.
What is asymmetric encryption?Uses two seperate keys to decrypt / encypt, one known as the public key and the other known as the private key.
What is hashing?Transforming data into fixed-sized values.
What is an entity?A category of an object, person, event or something that needs to be recorded.
What is the Primary Key?An unique identifier for each record in an entity and is underlined in the entity description.
What is the Composite primary key?Two primary keys needed to define a record.
What is the secondary key?Allows a database to be searched quickly with a more easy to remember key.
What are the three ways of relationships between entities?One-to-one, One-to-many, Many-to-many.
What is a foreign key?An attribute that links two tables together, with it being the primary key in the first relationship.
What is normalisation in databases?A way to help reduce data duplication when designing databases.
What are the three stages of normalisation?1NF, 2NF, 3NF
What is First Normal Form?No repeating attributes in a table and must be atomic, meaning a attribute cannot contain 2 data items.
What is Second Normal Form?A table in first normal form and no partial dependancies.
What is Third Normal Form?A table in second normal form with no non-key dependancies.
What are the main SQL commands?SELECT, FROM, WHERE, ORDER BY
How do you use a wild card?Using a * after a SQL command
How do you delete a table structure column in SQL?Using the ALTER & DROP commands.
How do you change the data type of a table structure column?Using the ALTER & MODIFY COLUMN commands.
How do you insert a new record in SQL?Using the INSERT INTO & VALUES commands.
How do you update data in SQL?Using the UPDATE, SET & WHERE commands.
How do you delete a record using SQL?Using the DELETE FROM & WHERE commands.
How do you add a new column in SQL?Using the ALTER TABLE & ADD commands.
How do you make a new table in SQL?Using the CREATE TABLE command.
What does URL stand for?Uniform Resource Locator
What is the physical structure of the Internet?"Backbone cables connected across different continents and then ISP's connect to the backbone to provide internet connection to homes and businesses."
"Which part of 'https://www.domainname.com/folder/subfolder/webpage.html' is the protocol?""'https://'"
"Which part of 'http://www.domainname.com/folder/subfolder/webpage.html' is the resource?""'webpage.html'"
"Which part of 'http://www.domainname.com/folder/subfolder/webpage.html' is the domain?"domainname.com
"Which part of 'http://www.domainname.com/folder/subfolder/webpage.html' is the subdomain?""'www.'"
What do Internet Registrars do?They hold all the records for existing websites and domains that are available to be purchase, they also allocate IP addresses for their global area.
What is the hierarchy of domain names?"The last domain in a URL, for example '.com' or '.org' is the top level domain and for each one behind it, it becomes 2nd level domain, 3rd level domain and so on."
What is DNS?Domain Name System, catalogues all domain names and their related IP addresses so when a webpage is requested using a URL, the browser can locate the corresponding IP from a local DNS server, if not found there, the search increases to a wider DNS server with a bigger database.
Why do we use DNS?"As it's easier to remember domain names instead of random numbers."
What is an IP Address?An Internet Protocol address is a unique address that is assigned to a network device and determines where a packet is to be sent or where it has been sent from and routers use this to direct it to the correct device.
What are the two types of Area Networks?Wide Area Networks and Local Area Networks.
What is a Wide Area Network?A network of interconnected networks over a large geographicalarea and often rely on third party carriers or infrastructure. 
What is a Local Area Network?A network that consists of devices on a single site or small geographical area, often connected together by cables and can communicate with all devices, including printers and scanners. They can transmit data very quick but over a small distance.
What are the advantages and disadvantages of using a bus topology?Advantages:<br>- Inexpensive to install<br><br>Disadvantages:<br>- Low Security<br>- Performance degrades with traffic<br>- If the main cable breaks, data cannot be transferred
What are the advantages and disadvantages of using a star topology?Advantages:<br>- If one cable fails, the system can still continue without that device<br>- Better performance speeds<br>- Easy to add new devices to the network<br><br>Disadvantages:<br>- Costly to install<br>- If central device goes down, no traffic can be transmitted
What is a physical topology?The actual design layout of a network
What is a logical topology?The shape of which the data travels within a network and how components communicate within a physical topology.
What is Wi-Fi?A wireless local area technology that allows you to connect a device to the internet via a wireless access point.
How does a computer connect to a wireless access point?Using a wireless network adapter, creating a station and it shares a single radio frequency channel to pick up transmissions from the wireless access point, either inside of a router or connected to a router.
What are the advantages of using a mesh topology?- No Cabling Costs<br>- Fast communication due to no central switch<br>- Easy to add new devices
How many devices need to be added to a mesh topology to connect to the internet?Only 1 device for all devices on a network.
What is circuit switching?A single connection between two endpoints in a network for the duration of a connection.
What is packet switching?A way of communicating packets of data across networks.
What are the characteristics of a packet?- Data broken into chunks mainly between 500-1500 bytes<br>- Contain a header, a payload and a checksum&nbsp;
What is a header in terms of data packets?Includes the sender and recipients IP addresses, the protocol being used and the order of which the packet is being sent in.
What is included in the payload in terms of data packets?The actual data of the packet.
What does the checksum do in terms of data packets?Detect transmission / corruption errors and to make sure that none of the data has changed since being sent.
How do you send packets across the internet?The packets from the senders router find the quickest route across the world to get to the recipients device and be reassembled in the correct order.
What does a router do?It is used to connect two networks together, reading the IP address from the packets and forwarding it to the recipient via the least congested route.
What is a gateway?If different networks use different protocols, a gateway is used by removing the header data and adding new data in the format of the new network before it sends the packet to its destination.
What is a MAC address?A address for each computer device and is hard-coded into the hardware and is used to uniquely identify the device and is 48 bits long and written as 12 hex digits.
What are the 4 layers of the TCP/IP protocol?Application Layer<br>Transport Layer<br>Network Layer<br>Link Layer
What does the application layer do?Encodes / decodes the message into a form using a protocol like HTTPS or FTP.
What does the transport layer?Breaks down the message being sent into small pieces into packets and each packet is given a number and the total number of packets
What does the network layer do?Adds the senders and recipients IP addresses to know where to send the message and where it came from
What does the data link layer?Enables the communication of packets between different networks.
Why has IPv6 been introduced?Because there are more and more devices going online with unique IP addresses and IPv4 cannot fit them all.
What is FTP?File Transfer Protocol is a way of transferring data across a network, often on the internet by uploading and sharing data in the application layer.
What are the three main email protocols?SMTP (Simple Mail Transfer Protocol)<br>POP3 (Post Office Protocol)<br>IMAP (Internet Message Access Protocol)
What does SMTP do?Used to transfer outgoing emails from server to another or from an email client to a server when sending an email
What does POP3 do?It retrieves emails from a mail server that teporarily stores them.
What is a firewall?A physical or digital security checkpoint designed to prevent unauthorised access between networks.
What is packet filtering?"It controls network access by examining the source and destination IP addresses in packet headers and if they match the permitted list, they are accepted onto the network, if not, it'll be blocked."
What is a proxy server?It intercepts all packets entering and exiting a network, hiding the real address of a source from the recipient, enabling privacy and anonymous surfing. It can also maintain a cache of the most visited websites so it does not need to reload the website and speed up the process. They are also used to filter requests on networks to prevent sensitive content from appearing on users devices.
What is a worm?A self-replicating virus that can replicate without any user interaction
What is a virus?A self-replicating malicious malware that needs to be opened to spread themselves and is memory resident when the file is executed turning all other uninfected files into infected ones.
What is a trojan?A piece of software or a file that pretends to be something usefull but provides a backdoor to your computer system for malicious acts to happen from a hacker - it can harvest your personal information, turn your device into a bot in a botnet or use your bandwidth but do not self-replicate.
What is HTML?HyperText Markup Language is a script that web pages are written in and contain the main structure and content of a site so the browser can render it properly.
What is CSS?Cascade Style Sheets link with HTML on web pages and dictate the style and visual formatting of the page instead of the content.
What are the two sections of a website in HTML?The head and the body
What does the head contain in HTML?The title of the website and any scripts that may enrich your page content.
What does the body contain in HTML?The main content of the page such as text, images and hyperlinks
What are web forms?Web forms enable websites to collect user inputted data such as textboxes and check boxes.
What is JavaScript?JavaScript is a script language that adds interactivity to websites with the manipulation of page objects, animations and forms and is interpreted instead of being compiled.
What is Search Engine Indexing and a Web Crawler?A web crawler is a piece of software that starts from a single page and fetches all the links linked by the starting site and repeats for a long time to create a databse of web pages known to the crawler, known as a Search Engine Index.
What do Web Crawlers look for in webpages when you search for something?"Keywords, meta tags and phrases that link to the search terms that you've searched."
What are meta tags?Data about the website including content and language used.
What is the PageRank Algorithm?Developed by Google, it is an algorithm that ranks pages on the index for how useful the sites will be to the user.
What is the PageRank Algorithm calculation?PR(A) = (1-d) + d(PR(T1) / C(T1) + ... PR(Tn) / C(Tn))<br><br>PR(A) = PageRank of page A<br>C(Tn) = Total count of outbound links from web page n<br>PR(Tn) / C(Tn) = Share of the vote that page A gets from pages T1&nbsp;<br>d = Dampening Factor, usually 0.85
Why is there a dampening factor in the PageRank algorithm?In probability terms, after six click-through links, the average user will stop their session or enter a new web address completely.
What is a client-server network?In this type of network, one or more computers are known as a client that connect to a central computer known as a server and all devices can access data and resources from the server. In a larger network, there may be several central servers that do different tasks such as a Mail Server and a Web Server.
What are the advantages and disadvantages of a client-server network?Advantages:<br>- Security is better and more secure<br>- Resources can be shared<br>- Backups are done centrally on the main server<br><br>Disadvantages:<br>- Expensive to install and maintain<br>- Dedicated professional IT staff required for upkeep of the network
What is cloud computing?A service based industry that provide access to software and files via the internet using a client-server based network remotely.
What is a peer-to-peer network?A peer-to-peer network is where there is no central server and all devices are connected to each other to share files.
What are the advantages and disadvantages of using a peer-to-peer network?Advantages:<br>- Cheap to setup<br>- Easy to maintain<br>- Easy to share resources&nbsp;<br><br>Disadvantages:<br>- Used for Online Piracy
Can a processing being done on either side in a client-server network?Yes
What do web servers do in terms of data processing?A client will send a request to a web server which should respond with the data requested or a suitable message otherwise and is often used for dynamic data that is always changing
Why is client-side processing used?"The client may have specific software to process the data or to remove traffic and the load on the server's processor - JavaScript is a type of language that is used for interactivity and is processed on the client-side."
Why is server-side processing used?It can process enormous amounts of data quickly for multiple clients and some languages used on sites may require a server such as SQL or PHP, which are used for search requests, validation may also be carried out on the server to check for any invalid entries on the server database.
What is an API?An Application Programming Interface is a set of protocols that control how two applications should interact with each other, such as the format of requests and responses from a server and client to allow data to quickly feed between the two.
What is the difference between thin and thick client computing?The thickness of a client computer refers to the level of processing and storage, the more processing a server does, the thinner the client becomes and vice versa.
What are the advantages and disadvantages of a thin-client?Advantages:<br>- Easy to maintain<br>- Secure as all data is kept in one place<br>- Software and updates can be installed on the server and easily distributed to all the nodes on the network<br><br>Disadvantages:<br>- If the server goes down, the clients lose functionality<br>- Requires a powerful and reliable server<br>- Sever demand and bandwidth increased
What are the advantages and disadvantages of a thick-client?Advantages:<br>- Robust and reliable<br>- Operate without a continous connection to the server<br>- Better for running more powerful applications<br><br>Disadvantages:<br>- More expensive<br>- Intergrity issues with distributed data<br>- Installation of software required on each node seperately
What are 1 dimensional arrays?An array that only has one row of elements
What are 2 dimensional arrays?An array that can be visualised as a table, with rows and columns
What are 3 dimensional arrays?An array that has columns and rows as well as depth.
What is a tuple?A set of values that can be any data type.
Do arrays have to be the same data type?Yes
What data structure is a queue?First in First Out
What can a queue be used for?An output that is waiting can be put onto a queue so more processes can happen but it can be immediately outputted when required from the queue or pressed characters on a keyboard that are held in a buffer.
Where is the front and rear of a queue?The front is where ever the first item is in the queue and the rear is where ever the last item is in the queue
What are the four queue operations?enQueue(item)&nbsp;<br>deQueue()<br>isEmpty()<br>isFull()
What does enQueue(item) do?Adds a new item to the rear of the queue
What does deQueue() do?Removes the front item from the queue and returns it
What does isEmpty() do?Tests to see whether the queue is empty.
What does isFull() do?Tests to see whether the queue is full
What type of data structure is an array?A static data structure
What is a static data structure?A data structure that is fixed in size and cannot increase or decrease.
What is a dynamic data structure?A flexible data structure that can change size and free up memory
What is a circular queue?A fixed data structure queue setup like a circle with elements until it has filled up and once items are dequeued and space is available, new items are added to the queue for whereever the old items were, but still become the rear no matter where they were.
What is a priority queue?A queue in that items are dequeued by removing them from the front of the queue with the highest priority at the front and the lowest priority at the back, making it possible that a new item can join the front of the queue.
What is a list?A abstract data type that consists of numbers of items that are sequenced
What are the operations used on lists?isEmpty()<br>append(item)<br>remove(item)<br>search(item)<br>length()<br>index(item)<br>insert(pos,item)<br>pop()<br>pop(pos)
What does isEmpty() do, in use for a list?Tests for the list being empty.
What does append(item) do, in use for a list?Adds a new item to the end of the list
What does remove(item) do, in use for a list?Removes the first occurance of the item from the list
What does search(item) do, in use for a list?Searches for an item in a list
What does length() do, in use for a list?Returns the number of items
What does index(item) do, in use for a list?Returns the position of the item
What does insert(pos,item) do, in use for a list?Inserts a new item at the position entered
What does pop() do, in use for a list?Removes and returns the last item in the list
What does pop(pos) do, in use for a list?Removes and returns the item at the position entered
What is a linked list?A dynamic data structure where the data is not held in required sequence
What is included in each node on a linked list?The data of the node itself and the pointer
What does a pointer do in a linked list?Points to where the next item in the list is
What does the last item point to in a linked list?"It uses a 'null' pointer"
What is a stack?A stack is a Last In, First Out data structure so the top of the stack leaves it first
What are stacks used for?Calculations and holding return addresses during subroutines
What are the operations of a stack?push(item)<br>pop()<br>peek()<br>isEmpty()<br>isFull()
What does push(item) do in terms of a stack?Adds a new item to the top of the stack
What does pop() do in terms of a stack?Removes and returns the top item of the stack
What does peek() do in terms of a stack?Returns the top item from the stack but does not remove it
What does isEmpty() do in terms of a stack?Tests to see if the stack is empty and returns True or False
What does isFull() do in terms of a stack?Tests to see if the stack is full and returns True or False
What would happen if an item was pushed onto a full stack?It would cause overflow and an error message would be given
What would happen if an item was popped from an empty stack?An underflow error would occur where there is nothing to remove
What is the hashing algorithm?key MOD spaces available
What would happen if an address was already full in terms of hashing?It would move up to the closer address available
What is rehashing?Finding an empty slot when a collision has occured
What is a hash table used for?A dictionary
What is a dictionary?An abstract data type where each data consists of two items, a key and a value
What is a graph?A set of nodes connected by edges, either one-way or two-way.
How do you show that an edge is one way in a graph?Add an arrow in the direction of the way you want
What are weights in terms of a table?The variable of travel between two nodes in a table
What are the advantages &amp; disadvantages of an adjacency matrix?Advantages:<br>- Easy to add<br>- Convenient to work with<br><br>Disadvantages:<br>- Empty cells with smaller tables<br>- More memory space wasted
What is an adjacency matrix?A two-dimensional array used to store information about a directed or undirected graph.
What is an adjacency list?A space-efficent way of implementing a graph with each of the nodes showing directly where it is linked to
What are the two ways of travelling through a graph?Depth-first and Breadth-first
What is Depth-first traversal?You go as far down one route before backtracking and taking the next root
What is Breadth-first traversal?Visiting the neighbours of the node and then of the first node visited and then the neighbours of the second node and so on
What are graphs used for?Computer networks and web pages / links
What is a tree?A data structure that lays out nodes
What are the main things included in a tree?A node, an edge, a rot, a child, a parent, a subtree and a leaf.
What is a node in terms of a tree?Contains the tree data
What is an edge in terms of a tree?An edge connects two nodes together
What is an rootin terms of a tree?A node that has no incoming edges and is at the start of the tree
What is an child in terms of a tree?Nodes that have incoming edges from the same node
What is an parent in terms of a tree?A node is a parent to all nodes that it is connected to with outgoing edges
What is an subtree in terms of a tree?A set of nodes and edges comprised of a parent and the descendents of the parents, can also be a leaf
What is an leaf in terms of a tree?A node that has no children
How many nodes can a binary search tree have?Only two node children
How do you construct a binary search tree?You place the first item at the root, and if the next item is greater than the first item it goes to the right, if it is smaller it goes to the left and so on and so on
What are the three ways of traversing a tree?Pre-order, in-order and post-order
What is pre-order traversal?"You start going as far as you can go to the left and back up to the lowest parent and the right node and repeating it till the top and repeat it on the right side.<br><img src=""paste-300be4e07773e00ada6cacf196419267049ac18c.jpg"">"
What is in-order traversal?"Traverse the left sub-tree, then visit the root, then traverse the right sub-tree<br><img src=""paste-fc1a0dc45c8b7f6c3707136b85c0b58a61c1e181.jpg"">"
What is post-order traversal?"Traverse the left sub-tree, then the right sub-tree and visit the root with it being top to bottom<br><img src=""paste-d776079d46ba620abc86f7ba1f139458d5dbba4f.jpg"">"
What is the CPU?Central Processing Unit
What are the components of the CPU?Control Unit, Buses, Arithmetic Logic Unit and Registers
What does the control unit do?Controls and co-ordinates the activities of the CPU, directing the flow of data between the processor and other devices
What is a bus?A set of wires that connect two or components together to transfer data
What are the three buses on the CPU?Address Bus<br>Control Bus<br>Data Bus
What does the address bus do?Sends address to the memory of a particular main memory location
What does the data bus do?Sends data found in a location to the CPU
What does the control bus do?Send control signals to components
What does the ALU do?Perform arithmetic and logic operations on data such as addition and subtraction
What are the five registers in the CPU?Program Counter<br>Current Instruction Register<br>Memory Address Register<br>Memory Data Register<br>Accumulator
What are registers?High speed memory cells
What does the program counter do?Holds the address of the next instruction to be executed
What does the current instruction register do?Holds the current instruction being executed
What does the memory address register do?Holds the address of the memory location from which data is to be fetched or written to
What does the memory data register do?Used to temporarily store data read or written from memory
What is the fetch decode execute cycle?1 - Address of the next instruction is copied from the PC to the MAR and the PC is increased by 1 to the next instruction<br>2 - Instruction held at the address is copied to the MDR<br>3 - MDR contents are copied to the CIR<br>4 - Instruction in the CIR is decoded and executed and the result is stored in the accumulator
What does an accumulator do?Stores the result of a calculation from the ALU
What are the three main factors affecting processor performance?Clock Speed, Amount of Cores and Amount of Cache Memory
What is the clock speed?The amount of cycles that a CPU can execute per second, measured in GHz / gigahertz
What is cache memory?Small, expensive amount of memory inside the CPU that can be quickly accessed with it storing data there instead of sending it back up to main memory, taking longer
What is Pipelining?Pipelining is a technique to help better CPU performance as it allows the next instructions to be fetched the same time as the CPU is performing operations
What is Assembly Language?Uses mnemonics to represent instructions, dividing them into an operand and an opcode in the Current Instruction Register
What are mnemonics?Short abbreviations of words used for code
What does the operand contain?The data or address of which the operation is to be performed
What does the opcode do?Specifies the type of instruction to be executed?
What is von neumann architecture?The basic components of a computer must have shared memory and buses used for both data and instructions and is built on the stored program concept meaning the instructions are fetched from memory one at a time
What is harvard architecture?This architecture has seperate memories for instruction and data and these can have different characteristics like the size of them and if they are read-only or not.
What are comparisons between Von Neumann and Harvard Architectures?"<img src=""paste-50ca3dd67485aa19b78275e5a78f0062b0664ac4.jpg"">"
"What type of architecture do modern CPU's have?"They incorporate for the most part elements of both von neumann and harvard architecture in one design
What is Complex Instruction Set Computers (CISC)?There is a large instruction set in CISC processors meaning they attempt to execute tasks in few lines of assembly code as possible
What is Reduced Instruction Set Computers (RISC)?A small instruction set is found in processors with RISC as each instruction is around one line of machine code and takes one clock cycle.
Compare between RISC and CISC:"<img src=""paste-bca189ea491044cc61ef72c9efd7a6ad59dea15f.jpg"">"
What is a co-processor?An extra processor used to help the functions of the main processor
What can a co-processor be used for?Perform floating point arithmetic, graphics processing and other functions
"How can multi-core CPU's achieve better performance?"They can distribute the workload over multiple CPU cores
How many cores does a quad-core have?4
What is a Graphics Processing Unit (GPU)?A specalised co-processor used for manipulating computer graphics, it has thousands of smaller cores designed to handle multiple taks simultaneously.
What are barcodes?An image used for indentifaction in applications like tracking parcels, entry to concerts and boarding trains.
What are the four types of barcode readers?Pen-type&nbsp;<br>Laser<br>Camera-based<br>CCD
What is a pen-type reader?A light source and a photo diode are placed next to each other in the tip of a pen and the photo diode measures the intensity of the light reflected back from the source and generates a waveform used to measure the width of the bars and spaces in the barcode
What is a laser scanner?Uses a laser beam as a light source to meaure the widths of the bars and spaces in the barcode
What is a camera-based scanner?Uses a camera to decode a 1D or 2D barcode
What is a CCD scanner?It is comprised of millions of tiny light sensors arranged ina grid and the binary data from each sensor is recorded onto a memory card so the image can be reproduced using suitable software on a computer
What is Radio Frequency Identification (RFID)?These tags can be used to identify and track things like bank cards and animals and contains a small microchip transponder and an antenna. Uses both an input and output, input to read the signal from a chip and output to transmit a signal from a tag.
What are active tags?RFID Tags that are larg as they contain a battery to power the tag so the tag can be recieved from further away
What are passive tags?RFID tags that do not have a battery and rely on radio faves from a reader nearby to generate enough electromagnetic power to the card
What is an output device?Data produced from a computer and turned into a form that humans can understand
What are the two types of screens?LCD<br>OLED
What is an LCD monitor?"Liquid Crystal Display (LCD) monitors contain groups of red, green and blue diodes to form each pixel and is backlit using LED's. They reach their maximum brightness immediately, the image is sharper with more realistic and vivid colours and consume very little power, producing little heat and saving running costs"
What is an OLED / Organic LED monitor?Brighter, thinner and lighter screens compared to LCD or LED screens and are made out of plastic instead of glass, so they are flexible - they require no backlighting so they consume less power and can refresh up to 200 times faster compared to LCD screens
What are the four types of printers?Laser<br>Inkjet<br>Dot Matrix<br>3D
What are laser printers?They offer high-quality, high-spreed printing using toner and is becoming more affordable and is often used as a home printer with black &amp; white and colour models
What are inkjet printers?They are printers that work by spraying dots of ink onto paper to create an image depending on the Resolution / Dots per Inch, creating photo-realistic images - they are cheaper than laser printers but take longer to print and have to be replaced more frequently.
What are dot matrix printers?A printer of which the print head has a matrix of pins that hit the surface of paper through an inked ribbon to form letters and can operate in damp or dirty environments but are noisy, slow and poor quality
What are 3D printers?New printers that can be used to create 3D items like car parts or medical equipment but are expensive and can be slow
What are computer speakers?Output audio from a device and external speakers often are more expensive but provide a higher sound of quality
What are actuators?Motors commonly used in conjunction with sensors to control a mechanism
Why do we need secondary storage?Contents of the storage remain there when the power is turned off unlike the RAM
What are the three types of secondary storage?Magnetic<br>Optical<br>Solid State
What is a hard disk?A magnetic secondary storage where a disk is spun at a very quick rate and read by a read / write head where it can change the magneticity of parts of the disk where magnetic is a 1 and non-magnetic is a 0
What are the advantages and disadvantages of a hard disk?Advantages:<br>- Large Capacity<br>- Cheap<br>Disadvantages:<br>- Less Portable<br>- Slow read / write speeds
What are the three formats of optical disks?Read-only (CD-ROM)<br>Recordable (CD-R)<br>Rewritable (CD-RW)
What is an optical disk?A laser is used to burn sections of its surface and then when it is read, a laser at a lower power is used to read the disk by shining a light onto the surface and a sensor is used to measure the amount of lights - reflective is 1 and non-reflective is 0 in binary. Another term for reflective and non-reflective is pits and lands.
What are the advantages and disadvantages of optical disks?Advantages:<br>- Highly portable<br>- Cheap to Produce<br>Disadvantages:<br>- Easy to break / damage
What are Solid State disks?Chips arranged on a board comprised of millions of flash memory cells and a controller that manages blocks of memory - with it being meant to look like a small hard disk drive
What are the advantages and disadvantages of a solid state drive?Advantages:<br>- Fast read / write speeds<br>- Consume less power compared to hard drives<br>Disadvantages:<br>- More expensive<br>- Less storage capacity
What are the two types of internal memory?Random Access Memory (RAM)<br>Read-Only Memory (ROM)
What is RAM?Used to store programs and data that is currently being used - it is volatile
What is ROM?Used to hold permanent information in memory, such as the bootstrap loader and information found within the BIOS and is non-volatile
What is volatile?Volatile means that the contents of the data are lost when the device has no power
What is virtual memory?When the RAM on a device is full and still needs more space, the hard disk is partioned to be used as memory where as less used applicaitons get copied into there as it is slower, freeing up space for more needed data in the actual RAM
What is an Operating System?A program that manages the operations of a computer for the user and is a bridge between the user and the hardware and is held in permanent storage
What are the functions of an operating system?Memory Management<br>Interrupt Service Routines<br>Processor Scheduling<br>Input / Output Management<br>User Interface<br>File Management
What is Memory Management?The OS operating with multiple applications and files at the same time and the allocation of space that each application gets
What are the two techniques for making the optimum use of memory?Paging and Segmentation
What is Paging?Splitting the memory into equal fixed size pages that can be swapped between the main memory and the hard disk as needed
What is segementation?Splitting the memory in division of logical processes of different lengths
What is an interrupt?An interrupt is a signal from a program, hardware or a clock from the CPU and may occur when a program terminates or when the printer runs out of paper
What is the interrupt service routine?When the CPU recieves an interrupt signal, it suspends the execution of the running processes and the ISR is brought in to deal with the interrupt and vary the interrupts with different priorities and turn off once dealt with.
What is processor scheduling?How a processor works when multiple programs and applications are running at the same time and how the CPU organises each process need as a core can only do one process at a time and is designed to be fair to all users and provide acceptable response time.
What are the five types of processor scheduling?Round Robin<br>First Come First Served<br>Shortest Remaining Time<br>Shortest Job First<br>Multi-level Feedback Queues
What is Round Robin scheduling?Processes are despatched on a first in first out basis with each process given a small amount of CPU time and if it does not finish before the time is up, the CPU is given to the next process
What is First come First served scheduling?Jobs are processed in the order in which they arrive with no priorities
What is Shortest remaining time scheduling?The process with the smallest estimated time till execution is run next with the CPU
What is a disadvantage of Shortest remaining time scheduling?The longer jobs will take longer before they get to be processed with the CPU
What is shortest job first scheduling?The process with the smallest estimated running time is run next
What are multi-level feedback queues?An algorithm creates several job queues and the jobs can move between queues depending on how much CPU time it uses and tries to keep the I/O devces busy so that a bottleneck does not occur and to maximise processor use.
What are the different operating systems?Distributed&nbsp;<br>Multi-tasking<br>Multi-user<br>Embedded<br>Real-time
What is a distributed operating system?It is a form of parallel processing system which spreads the load over multiple servers, a job is split up into several tasks that are ran over multiple servers within a network
What is a multi-tasking system?An OS that runs on a standalone computer where multiple applications can run simultaneously at the same time
What is a multi-user operating system?An operating system where multiple users have different profiles on a single computer with each user getting a slice of processor time according to a scheduling algorithm
What is an embedded operating system?An operating system designed for a specific hardware, it has a minimal UI, no RAM needed and no permanent data storage devices to be managed
What is a real-time operating system?An operating system that is time-critical and is designed to perform a task within a specific time frame and is found in situations where critical tasks are needed quickly like a flight-control system.
What is the BIOS?Stored in the ROM and is meant to initalise and test the system hardware components on startup and to load the operating system from the hard disk into the RAM
What is a device driver?A computer program that provides a software interface to a specific hardware device and allows operating systems to access hardware functions without the details of the hardware being used and communicates with the device using a system bus.
What is a virtual machine?Any instance where software is used to take on the function of the machine, such as emulating an operating system with different hardware
What are the categories of software?"<img src=""paste-5deb10745215a9dd0c32574b5b0e2c280c62909e.jpg"">"
What is Systems Software?"Software needed to run the computer's hardware and application programs including the OS, Utility programs and libraries."
What are utility programs?System software designed to optimise the performance of the computer or perform tasks such as back-up and compression
What are the five types of Utility programs?Defragmentation<br>Backup<br>Updating<br>Virus Checker<br>Compression
What is Defragmentation?"A Program that will reorganise files in a magnetic hard disk that are spread across the storage in blocks and moves them so they're all in order, therefore making the file read quicker"
What is Backup?Backup is where the application can save states of the computer so incase of any emergencies, the user is able to restore back to the previous state
What is updating?Updating is changing the version of the operating system or applications so that any bugs or anything malicious found can be patched up and help run the software more smoothly.
What is a virus checker?A software that searches your hard drive for any viruses and removes them
What is compression software?"This type of software shrinks files using compression techniques so they're quicker to send and take up less storage"
What is application software?General-purpose or bespoke software
What is general-purpose software?Software like a word-processor, spreadsheet or graphics packages
What is special-purpose software?Software designed for a single specific task or set of tasks like payroll and hotel book system programs.
What is the difference between off-the-shelf and bespoke software?"<img src=""paste-97ff8be64eb56c3f1a2bd1dd677b5677468553ca.jpg"">"
What is open source software?Software that is licensed for use but there is no charge for the licence, the source code is also freely available and developers can sell the software they have created
What is closed source software?Restrictions on how the software can be used, with different licenses for users and the person who wrote the software owns the copyright and the users of the program do not have access to the source code of the program
What is an assembler?Converts assembly code into machine code
What is assembly code?A low level language in which each instruction is equal to one machine code instruction
What is a compiler?A compiler converts a high-level language into machine code by scanning through it first, performing different checks and then outputs an executable machine code file and compiles all in one go.
What is an interpreter?An interpreter is a type of language translator from high-level to machine code via line by line and checks for errors as they go along
What is the comparison between a compiler and an interpreter?"<img src=""paste-31df067a67451c4a53bd35445cd9deff2c971f23.jpg"">"
What is bytecode?Source code that has been compiled into low-level code designed to be run on a vtual machine
What are the three stages of compilation?Lexical Analysis<br>Syntax Analysis<br>Code Generation &amp; Optimisation
What is lexical analysis?Removes spaces, comments and simple error-checks and then all keywords, constants and identifiers are replaced by tokens, which are unique symbols and then their addresses and data will be stored within a symbol table
What is a symbol table?It contains an entry for every keyword and identifier within a program so that the code can call back to each unique word
What is Syntax Analysis?The process of determing whether the sequence of input characters and symbols form a valid sentence in the code language
What is code generation and optimisation?Where the machine code is generated and translated into a number of machine code statements and optimised to run smoothly and have a smaller size, but will take longer to generate
What are libaries?Libaries are found within high-level languages that allow users to reference to pre-written code and specialist functions
What is a linker?Compilation of high-level programs and resolves cross-references between the files and creates a single executable program
What is black box testing?Testing carried out independently of the code used in the program and involves looking at program specification and creating a set of test data that covers input and outputs and functions
What is white box testing?Testing dependent on the code and is derived from the program structure rather than its function and is studied and tested where each path is tested at least once
What is alpha testing?"Testing carried out in-house by the developer's testing team"
What is beta testing?This type of testing involves giving the software out to users who agree to use the software and report any problems to the developers and allows for testing outside of the developer team.
What are the five stages of development?Analysis<br>Design<br>Implementation<br>Evaluation&nbsp;<br>Maintenance
What are the three types of development lifecycle models?Waterfall<br>Spiral<br>Agile
What is the waterfall lifecycle model?Each step in the development process is completed one at a time from the beginning to the end, the client is involved at the beginning and then at the evaluation stage.
What is the spiral model?The spiral model still follows the main 5 development stages but creates many different prototypes of the software and repeats until a refined prototype is generated and the client is happy with the outcome and is used for large-scale projects
What is the agile lifecycle model?The agile lifecycle model allows for flexability in development and quick changes in client requirements where stages of development may not be completed one after another, allowing some parts to be done and others not and has constant feedback from the clients to change the parts of the system.
What is extreme programming?A type of agile development where the dev team consists of a pair of programmers and a client where they aim to produce high-quality code and be critiqued by each other and has high communication and is produced quickly but with great quality
What is Rapid Application Development (RAD)?Workshops and focus groups to gather requirements instead of a document, prototypes continually refine the system in response to feedback and user involvement, reusing any software components that have been already used and producing within a strict time limit for each part of the system
What are the advantages and disadvantages of the waterfall system lifecycle?Advantages:<br>- Suitable for small projects<br>Disadvantages:<br>- Lack of user involvement
What are the advantages of the spiral system lifecycle?Uses prototypes to determine what user requirements are needed
What are the advantages of the rapid application development system lifecycle?Good for large projects with a danger of getting sidetracked with improvements
What makes a good algorithm?Clear and precise steps that produce the correct output<br>Allow for invalid inputs<br>Terminates at some point<br>Executes efficiently in as few steps as possible<br>Designed so other people can understand and modify it
What are different type of algorithms used?Internet-related, route-finding, compression and encryption.
What is a programming paradigm?A style of computer programming that tackle problems in major different ways.
What are the four types of programming paradigms?Procedural, Object-oriented, Declaritive and Functional
What is procedural programming and an example of it?An example is Python and it is a series of instructions that tell the computer what to do with the input to solve the problem.
What is a type of procedural programming and what does it do?Structured programming, and it uses programming constructs of sequence, selection, iteration and recursion with modular techniques to split large programs into smaller, more managable chunks.
What is object-oriented programming and an example of it?An example is Java and it is a language designed to abstract details of implementation away from the user and make it more reusable and easy to maintain.
What is declarative programming and an example of it?An example is SQL, and it is where you write statements that describe the probelm to be solved.
What is functional programming and an example of it?An example is C#, and it is statements that are written as a series of functions which accept input data as arguments and return an output.
What is involved in an object-oriented language?There is a class, which is defined as a description of what the data looks like (properties) and what it can do (methods). The user only sees the state and behaviour of the data item and data items are called objects, where an object is an instance of a class.
What is inheritance?The classes and its subclasses found within an object-oriented programming language where they can have the same and different attributes
What is polymorphism?"A programming language's ability to process objects differently dependent on their class"
What is encapsulation?The process of combining methods and procedures to form an object
What are the advantages of object-oriented languages?New objects can be easily created with small differences to existing objects<br>Objects that are already defined can be reused<br>More planning from designers helps make better designs with less weaknesses<br>The source code of an object can be tested indepentently of the code of others<br>Provides a good framework for different code libraries
What are the different codes for assembly languages and their description?"<img src=""paste-551246cb42f12432b399c86f0ad83efe3dbf856e.jpg"">"
What are the four different addressing modes?Immediate<br>Direct<br>Indirect<br>Indexed
Where is the operand stored in immediate addressing?The actual value to be operated on
Where is the operand stored in direct addressing?The operand holds the memory address of the value to be operated on
Where is the operand stored in indirect addressing?The location which holds the address of the data we want
Where is the operand stored in indexed addressing?The address of the operand is obtained by adding to the contents of the index register
"How do you load 4 into the accumulator of each addressing mode?<br><img src=""paste-fd9cdfeae3d528dea77ccf7df5e78f30a57c94c1.jpg"">""<img src=""paste-7874c5e701eb72a92de098c096f491e8e0f3abce.jpg"">"
What are examples of a primitive data type?An integer, float, boolean, character and string
What is denary?Number system from 0-9
What is binary?Number system using only 0 and 1
What is hexadecimal?Number system with a base of 16, with numbers 0 to 9 and letters A to F.
How do you convert binary to hexadecimal?You split the binary number into groups of 4 binary digits and translate
Why is hexadecimal used?It is better to represent a byte in just two digits and there are less mistakes likely to be made compared to binary and it is also used for colour codes and determining the RGB values of a colour.
What is a bit?A unit of information in the form of either a 1 or a 0, representative of either on or off.
What is a byte?A set of eight bits and holds one character of text.
How do you find out the number of values that can be represented by a certain amount of bits?2^n where n = number of bits
What are the different levels of bytes?"<img src=""paste-6195f85ebad8862b9ea62c5d35b56aa8b248bfa0.jpg"">"
What is ASCII?ASCII is a character set that is 7 bits long and represents 128 characters, it is also known as American Standard Code for Information Interchange.
What happens when you add characters together in ASCII?They join up instead of addition, so 7 + 7 would equal 77.
What is Unicode?Another character set that allows for over a million characters and unique characters from all languages, with there being 8-bit, 16-bit and 32-bit versions.
What is similar between ASCII and Unicode?The first 128 codes in both ASCII and Unicode are used to represent the same characters
What are the rules of binary addition?0 + 0 = 0<br>0 + 1 = 1<br>1 + 0 = 1<br>1 + 1 = 0 (Carry 1)<br>1 + 1 + 1 = 1 (Carry 1)
What is overflow?When the result of a binary calculation goes beyond 8 bits
What is the MSB / Most significant bit?The leftmost bit represents if a number is positive or negative where if it is a 0, it is positive and if it is a 1, it is negative.
"How do you represent negative numbers using two's complement?""You flip the positive number so that the 0's become 1's and the 1's become 0's and then you add 1 to that number."
What is fixed point binary?"This is a useful way to represent fractions in binary and a binary point is used to seperate whole numbers from fractional numbers.<br><img src=""paste-b952391549ed7400f39b9d2f7c36aeb06cae834f.jpg"">"
What is floating point binary?Where a number is represented as a mantissa and an exponent, similar to 3.1x10^6 where 3.1 is the mantissa and 6 is the exponent.
Does floating point binary use MSB or twos compliment?Most Significant Bit
"Where is the binary point moving to in this binary and what is the denary value?<br><img src=""paste-4fe539c4275ffdecb9ad28b36d85138bcce94e59.jpg"">"It will move from 0.1101 to 0110.1 as the exponent is 3 and as it is positive, it moves right 3 times. The result will be 4 + 2 + 1/2 = 6.5
Which way does the decimal point go if the exponent is negative?Left
Which way does the decimal point go if the exponent is positive?Right
What are the main parts of floating point binary?"<img src=""paste-cc62d03196517de54221ddb9236fe803ae6b3a9c.jpg"">"
What is normalisation in floating point binary?The process of moving a binary point to provide the maximum level of precision for the number, making the first digit the most significant digit.
What are the two rules in normalisation?If it is a positive number, it has a sign bit of 0 and the next digit is 1<br>If it is a negative number, it has a sign bit of 1 and the next digit is 0
How do you convert a decimal number into floating point binary?You convert the decimal number into a fixed point binary and then normalise it, to do this you see how many spaces it takes to reach the most significant bit and the opposite of that is the exponent.
How do you convert 14.625 into floating point?"<img src=""paste-252239eb576a8392943e494947daa061b24c13a7.jpg""><br><img src=""paste-f296e3a98c2a3983f22f9988ad70fe8377aa4d75.jpg""><br>Therefore the exponent would be 0100 as it moves four to the right and the mantissa would be 01110101.&nbsp;<br>"
How do you normalise a binary digit that starts with 0001?You would move it two places to the left, getting rid of the 00 at start so it becomes 0100 and the exponent would be 2 less than the normal exponent.
How do you normalise 00011010 0101?You move 00011010 up two spaces to become 01101000 and the exponent would go from 0101 (5) to 0011 (3) as you take away the amount of spaces moved to the right
How do you add or subtract floating points together?You line up the points making the exponents equal<br>Add or Subtract the mantissas<br>Normalise the result
What is underflow?When a number is too small to be represented in the alloted number of bits
What is a carry bit?The bit that is removed after a shift is performed
Which way can a shift go?Left or right
What happens in a logical shift left &amp; right?Shift right causes the LSB / Least significant bit to be pushed into the carry bit<br>Shift leftcauses the MSB / Most significant bit to be pushed into the carry bit
What is an artihmetic shift?A shift left or right but the sign bit remains the same.
What happens with an arithmetic shift left or right?Shift right divides the number by 2 and the MSB moves and stays the same<br>Shift left times the number by 2 and the MSB is skipped and stays the same
How do you times numbers by an odd number using arithmetic shift?1You add the number x 1 and the number x the closest even number like 9x5, which is (9x1) + (9x4).
What is a circular shift?Moving the binary number either left, which will cause the furthest left number to be on the right side and right, which will cause the furthest right number to be on the left side.
What is XOR?The binary numbers must be opposites of each other, so 1 and 0 with a XOR mask would be 1 but 1 and 1 with a XOR mask would be 0.
What is the data protection act of 1998?Anyone who stores personal details of a user must keep them secure
What are the requirements of the data protection act of 1998?Data must be processed lawfully and fairly<br>Data must be accurate and up to date<br>Data must not be retained for longer than necessary<br>Data must be kept secure<br>Data can only be used for the purpose of which it was collected
What is the computer misuse act of 1990?Laws to prevent unauthorised access of programs and data including unauthorised access to computer material, with intent to commit a crime or modifications of computer materials.
What is the Copyright Designs and Patents Act 1988?Set of laws designed to protect the creators of books, music, video and software from having their work illegally copied by making it illegal to use, copy or distribute commerically available software without purchasing the correct license
What is the Regulation of Investigatory Powers Act of 2000?"It regulates the powers of public bodies to carry out surveillance and investigation and covers the interception of communication. It enables mass surveilllance of communications in transit, it enables certain public bodies to demand an ISP to provide access to a customer's communications in secret and allows public bodies to monitor people's internet activities."
What is a NOT gate?It inverts the input, so if an input is 0, it will output 1 and if an input is 1, it will output 0.
What is a NOT gate symbol?"<img src=""paste-b98a123e4de0b01db8b8c922b4db56c7538424df.jpg"">"
What is the boolean algebraic expression of a NOT gate?"<img src=""paste-66bb7b9241470f6ce8e163b28420eaf2dcaac799.jpg"">"
What is an AND gate?"The output of 2 inputs will be 1 only if both inputs are 1.<br><img src=""paste-f5ba58828e992553013083eeda3bec5739ee4150.jpg"">"
What is the symbol for an AND gate?"<img src=""paste-e12b543cfe230039a414bdb5022f71edcc789dec.jpg"">"
What is the boolean expression for an AND gate?"<img src=""paste-1b5ba5724f5c656619c57512162515a13cf3f6e8.jpg"">"
What is an OR gate?"Where if one or both of the inputs include a 1, it will output a 1<br><img src=""paste-07883e276ff0e6be04406517c50dd8b422dfc675.jpg"">"
What is the symbol for an OR gate?"<img src=""paste-a46c9e20208a519d076fd53d7bc53b569208eaca.jpg"">"
What is the Boolean expression for an OR gate?"<img src=""paste-0411892c5beb1d5161c7deaa5677bb0d5829a659.jpg"">"
What is a XOR gate?"Exclusive OR, the output will be a 1 only if one or the other input is a 1 and <br>cannot be both<br><img src=""paste-435925fef87620e0c2641681467cfea4b97b4dca.jpg"">"
What is the symbol for a XOR gate?"<img src=""paste-f814865f9f984ba29d8be07612a4dc6621334351.jpg"">"
What is the boolean expression for a XOR gate?"<img src=""paste-badddb0648cc19883706711a2cb41817c4f40e25.jpg"">"
"What are de Morgan's laws?""Any boolean function can be converted to one which used only NAND (NOT AND) or only NOR (NOT OR) functions.<br><br>Therefore,&nbsp;<img src=""paste-44eaadfc40aee2dee138fb18a968a939deaee698.jpg"">and&nbsp;<img src=""paste-942d8038b89e3f24d4b7f8ced2ce61f628d6e47f.jpg"">"
"How do you implement de Morgan's laws?"Complement both terms in the expression like A, B<br>Change AND to OR and OR to AND<br>Invert the Result
What is a Karnaugh Map?It provides an alternative way of simplifying Boolean expressions and is similar to a truth table and allows us to easily detect groupings of expressions with common factors
What is the correspondence between a truth table and a karnaugh map?"<img src=""paste-ca6ab271ba0960d18ce36ee725868903ac37e8c5.jpg"">"
"<img src=""paste-03fcbc4329df53fff103c460f9d7aa4484a98970.jpg"">""<img src=""paste-a90b4da38ecef475964726b25505ce5dc1acc9f3.jpg"">"
How do you arrange a term that has two numbers in a karnaugh map?You arrange it so there is only one change in the variable at the time, like 00 to 01 to 11 to 10.
How do you construct a karnaugh map?"<img src=""paste-081ca1aaabcdf51e2a0fb6aa640a9a0d507ae4d3.jpg"">"
What is a half adder?A half adder can take an input of two bits and give a two-bit output as the correct result of an addition of the two inputs
"What would be the values of S and C for this equation?<br><img src=""paste-f515f26e9a6378d1de61f955fb0c393bb3fbcc4a.jpg"">""<img src=""paste-745bfce97cbeb1dbf9ed20ad361857459e1c08b4.jpg"">"
What is a full adder?A full adder combines two half adders to add three bits together including the two inputs A and B and also the carry bit C.
"What are the values of S and C(OUT)?<br><img src=""paste-06b6c950bfee0a55185d829760d1bef43295d8fb.jpg"">""<img src=""paste-333417c8e42d0761e029b3d84bea8da213fff140.jpg"">"
What is a flip flop?An elemental sequential logic circuit that stores one bit and flips between two states, 0 and 1 and has two inputs, a control input labelled D and a clock signal.