Computing Flashcards
What is hardware?
Physical components that make up a computer system
What is software?
Programs or applications that a computer system runs
What is an embedded system?
A computer which is designed to perform 1 specific task
What are the advantages of an embedded system?
- Easier to design
- Cheaper to produce
- More efficient at their task
What does the processing power of the CPU depend on?
- Clock speed
- Number of cores
- Cache size
What does the CPU do?
Manages the fetch, decode, execute cycle. Also controls the flow of data inside the CPU
What does the ALU do?
Performs arithmetic and logical operations
What does cache do?
A very fast memory that temporarily stores data and instructions that the processor is likely to reuse
What does the program counter do?
Holds memory address of next instruction for each cycle
What does the accumulator do?
Stores results of calculations from the ALU
What does the MAR do?
Holds any memory address about to be used by the CPU
What does MDR do?
Holds the actual data or instruction, which is either fetched from memory or waiting to be written to memory
What is volatile memory?
Memory that requires power to retain its data
What does RAM do?
Holds data and instructions which are currently being used
What does ROM do?
Contains instructions a computer needs to properly boot up.
The instructions are known as BIOS (Basic Input Output System)
What is primary storage?
The memory areas that hold data currently being used. It has the fastest read/write speed.
What is secondary storage?
A non-volatile storage of data that’s not in use. Read/write speeds are slower than primary storage.
What are some examples of primary storage?
- RAM
- ROM
- Cache
- Flash memory
What are some examples of secondary storage?
- Hard disk drives
- USB memory sticks
- Optical storage devices
- Solid state devices
What are the functions of the operating system?
- Communicate with internal and external hardware
- Provide a user interface
- Provide a platform for applications to run
- Allow the computer to multitask by controlling memory resources
- Deal with file and disk management
- Manage security
What is encryption?
Scrambling data and providing the receiver with the key to unscramble so it is unreadable by unauthorized users.
(Note that unauthorized users can still receive data, but not read it)
What is defragmentation?
The process of reorganizing files on a hard drive so that related data is stored together in continuous blocks
What is lossy compression?
Permanently removing data from files to reduce size
What is lossless compression?
Temporarily removing data to store a file but then restoring it to its original state when opened
How many bits does ASCII use and how many characters does this allow?
- 7 bits
- 128 characters
How many bits does extended ASCII use and how many characters does this allow?
- 8 bits
- 256 characters
What does 1 left shift do to a binary number?
Doubles it
What does 1 right shift do to a binary number?
Halves it
What is the formula for calculating the size of a text file?
Bits per character x Number of characters
What is the formula for calculating the size of an image file?
Resolution x Colour depth
OR
Width x Height x Colour depth
What is the formula for calculating the size of a sound file?
Sample rate (Hz) x Bit depth x Duration (s)
What is the conversion rate between all units of data?
Bit (b)
x4
Nibble
x2
Byte (B)
x 1000
Kilobyte (kB)
x1000
Megabyte (MB)
x1000
Gigabyte (GB)
x1000
Terabyte (TB)
x1000
Petabyte (PB)
What are the advantages and disadvantages of lossy compression?
Advantages
- Greatly reduced file size
- Files take up less bandwidth
- Lots of software can read lossy files
Disadvantages
- Lots of data lost
- Cannot be returned to original state
- Cannot be used on text and software files
- Worse quality
What are the advantages and disadvantages of lossless compression?
Advantages
- Data is only temporarily removed
- File should sound or look like the original
- Can be returned to original state
- Can be used on text and software files unlike lossy
Disadvantages
- Only a slight reduction in file size
What does LAN stand for and what does it do?
Local Area Network
Connects devices over a small geographical area in a single site
What does WAN stand for and what does it do?
Wide Area Network
Connects devices or LANs across a large geographical area
What does NIC do and what does it do?
Network Interface Card
An internal piece of hardware that allows a device to connect to a network
What does a switch do?
Connects devices on a LAN by receiving and forwarding data packets
What does a router do?
Directs data from one LAN to another
What does a Wireless Access Point do?
Allows wireless access to a network
What is bandwidth?
The amount of data that can be transferred in a given time
What are the advantages and disadvantages of client-server networks?
Advantages
- Easier to keep track of files as they’re stored centrally
- Easier to perform back-ups
- Easier to install and update software
- Easier to manage network security
- Servers are very reliable and always on
Disadvantages
- Expensive to set up
- Requires IT specialists to set up and maintain
- Very dependent on the server
- Server can be overloaded
What are the advantages and disadvantages of peer-to-peer networks?
Advantages
- Easy to maintain
- No dependence on a server
Disadvantages
- No centralised management
- Easy to lose track of what files are stored
- Peer machines are less reliable
- Machines are prone to slowing down when other devices access them
What does TCP/IP stand for and do?
Transmission Control Protocol / Internet Protocol
Sets rules on how devices connect on a network
What does HTTP stand for and do?
Hyper Text Transfer Protocol
Allows a client to request info from a web server and receive a response
What does HTTPS stand for and do?
Hyper Text Transfer Protocol Secure
Encrypts data between a user and a website
What does FTP stand for and do?
File Transfer Protocol
Used to access, edit and move files between devices on a network
What does POP3 stand for and do?
Post Office Protocol (Version 3)
Used to retrieve emails from a server. Emails are held on a server until you download it.
What does IMAP stand for and do?
Internet Message Access Protocol
Used to access and manage emails on a remote mail server
What does SMTP stand for and do?
Simple Mail Transfer Protocol
Used to send emails
What does DNS stand for and what does it do?
Domain Name Server
Translates website domain names into IP addresses
What are the advantages and disadvantages of cloud storage?
Advantages
- Users can access files from any connected device
- Easy to increase available storage
- No need to buy expensive hardware
- No need to pay IT staff to manage hardware
- Cloud host provides security and back-ups for you
- Cloud software is updated automatically
Disadvantages
- Internet connection required
- Dependent on host
- Data can be vulnerable to hackers
- Unclear ownership rights
- Subscription fees may be expensive
What are user access levels?
Restricting specific users on what they have access to
Which methods are used to attack networks?
- Malware
- Brute-force attacks
- Social engineering
- Denial of service
- Data interception / theft
- SQL injection
How can network attacks be prevented?
(Name as many as you can)
- Anti-malware software
- Firewalls
- Physical security like locks to doors and biometrics
- Strong passwords
- Encryption
- Penetration testing
- User access levels
What is a MAC address?
A unique identifier for a device that is connected to a local network
What is an IP address
A unique identifier for a device that is connected to a global network
Which chemicals can produce e-waste?
(Name as many as you can)
- Lead
- Cadnium
- Mercury
- Nickel
- Arsenic
- Zinc
- Antimony
- Beryllium
What is e-waste?
The disposal of electronic devices
What is the Data Protection Act (1998)?
A law that regulated how businesses could use personal information, protecting data misuse
What is the Computer Misuse Act (1990)?
A law that criminalized accessing or modifying data without permission
What is the Copyright Designs and Patents Act (1988)?
A law that protects the rights of a creator to their work
What is copyright?
A legal term used to describe the rights a creator has over their work
What is licensing?
A legal agreement that outlines the use and redistribution of computer software
What is a trademark?
A sign that is used to identify a company or brand and distinguishes its products and services from others
What is a patent?
A legal protection that gives the owner exclusive rights to an invention
What is a stakeholder?
A person or group of people who are affected by or have interest in the actions of an organisation or product
What is open source software?
Software that is free to use and allows users to access, modify and distribute the source code
What is proprietary software?
Software that is owned by a company and protected by copyright
What are the advantages and disadvantages of open source software?
Advantages
- Usually free
- Made for greater good, not profit
- Software can be adapted to fit needs
- Wide pool of collaborators can be more creative than programmers of 1 company
- Problems are quicky solved by the community
Disadvantages
- Small projects may not get updated and get buggy
- May have limited user documentation
- No warranties if something goes wrong
- No customer support
- Companies using open source may not want competitors to see their code
What are the advantages and disadvantages of proprietary software?
Advantages
- Comes with warranties, documentation and customer support
- Should be well-tested and reliable
- Usually cheaper for companies than developing their own custom software
Disadvantages
- Can be expensive for users
- Software may not fit a user’s needs
- Companies may not maintain older software to persuade people to buy the latest product
What is decomposition?
Breaking down a complex problem into smaller, more manageable problems
What is abstraction?
Picking important parts of a problem and ignoring unneccessary detail
What is algorithmic thinking?
A logical way of getting from a problem to a solution
What is the symbol for a process in a flowchart?
Rectangle
What is the symbol for the start/end of a flowchart?
Oval
What is the symbol for a decision in a flowchart?
Diamond
What is the symbol for an input/output in a flowchart?
Parallelogram
What is computational thinking?
A systematic approach to solving problems
What is an integer?
A whole number
What is a real (or float)?
A decimal number
What is Boolean?
A data type that has one of 2 values
(e.g. true/false or yes/no)
What is a character?
A single letter, number or symbol
What is a string?
A collection of characters
What are the 3 programming constructs?
- Selection
- Sequence
- Iteration
What is a selection?
(Programming construct)
The process of decision-making
What is a sequence?
(Programming construct)
The order that commands are executed
What is an iteration?
(Programming construction)
Repitition of code
What is the typical operator for addition?
+
What is the typical operator for subtraction?
-
What is the typical operator for multiplication?
*
What is the typical operator for division?
/
What is the typical operator for exponentiation?
^ OR **
What is the typical operator for an integer while dividing?
DIV
What is the typical operator for remainder while dividing?
MOD
OR
%
What is the code to open a file?
file = open()
What is the code to create a new text file?
newFile()
What is the code to write in a text file?
file.writeLine()
What is the code to read a file?
file.readLine()
What is the code to close a file?
file.close()
What are the 3 key words when searching for data in SQL and what do they mean
SELECT - the column you want to search
FROM - the name of the table
WHERE - specific conditions (e.g.
score < 5)
What does:
1) a function do?
2) a procedure do?
Function: returns a value
Procedure: performs a task but doesnt return value
What is a:
1) local variable
2) global variable
Local: a variable only existing in a specific subroutine
Global: a variable that can be accessed and changed throughout an entire program
What are the 5 types of checks?
- Range check
- Format check
- Length check
- Presence check
- Type check
What is input validation?
Checking if data meets certain criteria before passing into a program
What is authentication?
Verifying the identity of a user before they’re allowed to access certain pieces of data or features of a program
What is a syntax error?
An error that breaks the grammatical rules of programming, stopping it from running
What is a logic error?
An error when code is entered correctly, but doesn’t output the desired output
What is iterative testing?
Testing a program while it is being developed
What is final (terminal) testing?
Testing a program at the end of the development process
What are 4 data types?
- Normal data
- Boundary data
- Erroneous data
- Invalid data
What is normal data?
Data that is accepted by the program
What is boundary data?
Values at the limit of what the program can accept/handle
What is erroneous data?
Data inputs of the wrong data type
What is invalid data?
Data of the correct data type, but is outside of the accepted/handleable range
What does a NOT gate do?
Reverses the input value. (1 becomes 0 and 0 becomes 1)
What does an AND gate do?
Returns 1 only if both inputs are 1
What does an OR gate do?
Returns 1 if one or both inputs are 1
What are the characteristics of a high-level language?
- One instruction represents many instructions of machine code
- Same code will work for many different machines and processors
- Easier to debug
- Must be translated before a computer can understand it
What are the characteristics of low-level language?
- One instruction of assembly code represents one instruction of machine code
- Works on one type of processor
- Harder to debug
- Directly executable
What does an interpreter do?
- Translates and runs source code one instruction at a time
- Returns the first error found and then stops
- Programs run slower
- Can only be run on 1 machine
- Creates object code
What does a compiler do?
- Translates all source code at once
- Program won’t run if there is a syntax error
- Programs run faster
- Executable file can be run by multiple machines
- Creates an executable file
What does IDE stand for?
Integrated Development Environment
What are the features of IDE when:
1) writing code
2) running code
Writing code
- Code editor
- Bracket matching
- Auto-complete
- Syntax checking
Running code
- Run-time environment
- Debugging
- Error diagnosis
What is metadata?
Data about a file or image file
What does utility software do?
Helps maintain and manage a computer system by:
- Managing files
- Creating software backups
- Using antivirus/anti-malware
- Disk defragmentation
- Compressing files
- Encrypting data
