Computer Science Concise Notes

A comprehensive collection of vocabulary flashcards based on the lecture notes for computer science, aiding in study and retention of key concepts.

Benefits of BCD

• More straightforward to convert between BCD and denary

• Less complex to encode and decode for programmers

• Easier for digital equipment to display information

• Can represent monetary values exactly

Applications of BCD

• Used in electronic displays like calculators and digital clocks

• Storage of date and time in BIOS

Applications of Hexadecimal

• Used for MAC addresses

• HTML color codes

• Memory addresses in assembly language

ASCII Representation

• Each character has a unique code

• The character is replaced by its corresponding code

• Stored in the same order as in the word

Character Set

• All of the characters that the computer can represent or use
• Each character has a corresponding unique binary number

Similarities between Character Sets

• All can use 8 bits
• ASCII is a subset of Unicode/Extended ASCII
• Each represents characters using a unique code

Differences between ASCII and Unicode

• Unicode can represent multiple languages and a wider range of characters than ASCII
• ASCII is 7-bit
• Extended ASCII is 8-bit
• Unicode is 16-bit

Bitmap Graphic

• Made up of pixels, each of a single color
• Stored as a sequence of binary numbers
• Prone to pixelation when enlarged

File Header

• Stores data about the bitmap image
• Includes color depth, image resolution, and file type

Image Resolution

• Total number of pixels in an image
• Increasing resolution means more pixels
• Results in sharper images

Bit depth/Colour depth

• Number of bits used to represent each color
• Determining the number of colors that can be represented

Vector Graphic

• Stores a set of instructions about how to draw the shape
• Does not pixelate when scaled
• Smaller file size

Drawing Object

• Component of vector graphic created using a formula or command

Drawing Properties

• Data about the shapes within a drawing
• Defining appearance

Drawing List

• The list of shapes that make up an image
• Stores commands to draw each object

Sound Representation

• Amplitude is recorded at set intervals
• Each amplitude assigned a corresponding unique binary value

Sampling

• Taking measurements at regular intervals
• Storing the values

Sampling Rate

• Number of samples taken per unit time
• Increasing the sampling rate captures more details

Sampling Resolution

• Number of bits used to store each sample
• Higher resolution captures a wider range of amplitudes

Digital Waveform

• Closer representing the original sound
• Improved accuracy

Analogue Data

• A variable data value that is constantly changing

Compression Reasons

• Reduces file size for efficiency in storage and transmission
• Helps improve download rates

Lossy Compression

• Original data is lost
• File cannot be reconstructed
• Used where some data is not required

Lossless Compression

• Original data is preserved
• Used where full data restoration is needed

Run-length Encoding (RLE)

• Groups consecutive sounds or colors to reduce data size

LAN (Local Area Network)

• Allows communication and sharing of resources between devices
• Covers a small geographical area

WAN (Wide Area Network)

• Covers a large geographical area
• Often uses virtual connections
• Lower data transfer rates

Client-Server Model

• Web pages or resources are stored on servers
• Clients send requests and servers respond

Peer-to-Peer Network

• Computers are of equal status
• Each node provides access to data/resources

Thick Client

• Client performs most processing locally
• Minimal tasks required from the server

Thin Client

• Client relies heavily on the server for processing and data storage

Star Topology

• Devices connected to a central device (hub or switch)
• Reduces collisions and improving performance

Mesh Topology

• All devices connected to one another
• Multiple routes available
• Improving reliability

Cloud Computing

• Accessing applications or files on remote servers via the internet

Public Cloud

• Services available to anyone over the public internet

Private Cloud

• Services offered by internal networks to specific users

Wired Network Advantages

• Higher bandwidth
• More reliable connections
• Better security

Wireless Network Advantages

• Freedom of movement
• Easy scalability
• Less cabling required

Copper Cables

• Data transmitted through electrical signals
• Lower transmission rate compared to fibre

Fibre-optic Cables

• Data transmitted via light signals
• Offering higher bandwidth and faster speeds

Radio Waves

• Data carried wirelessly through electromagnetic waves

Switch

• Allows communication between devices
• Connects individual devices together within a network

Router

• Routes data packets between networks
• Manages access to resources

Ethernet Protocol

• Used for data transmission over wired networks
• Applying CSMA/CD for collision detection

Bit Streaming

• Continuous data transmission
• Often used for video or audio content

Real-time Streaming

• Media is sent directly to users as it is recorded

On-demand Streaming

• Users can watch pre-recorded media at their convenience

URL (Uniform Resource Locator)

• Address used to access resources on the Internet

IPv4

• Internet Protocol version 4
• Using 32-bit addresses

IPv6

• Internet Protocol version 6
• Using 128-bit addresses
• More addresses available than IPv4

Dynamic IP Address

• Assigned anew each time a device connects to the network

Static IP Address

• Fixed address that does not change over time

Subnetworking Benefits

• Improved security by limiting data access
• Better traffic management

Public IP Address

• Visible globally
• Allocated by an ISP

Private IP Address

• Visible only within a local area network

Data Security

• Protection against data loss or corruption

Data Privacy

• Protection against unauthorized access to personal data

Data Integrity

• Ensures accuracy and consistency
• Information is kept up-to-date

Two-Factor Authentication

• Enhances security
• Requiring two forms of verification

Biometric Passwords

• Using biological traits (like fingerprints or iris scans) for authentication

Firewall

• Monitors and controls incoming and outgoing network traffic

Anti-malware Software

• Scans for and removes malicious software

Backups

• Creating copies of data for recovery purposes in case of loss

Encryption

• Converts information into a secure format
• Prevents unauthorized access

Validation

• Checks data for reasonableness and correctness

Verification

• Confirms data accuracy by comparing it with the original source

Parity Check

• Ensures data integrity by sending an extra bit for error detection

Checksum

• Value sent with data to verify its integrity upon receipt

Data Dictionary

• Contains metadata about the database
• Stores field names, types, and constraints

DBMS (Database Management System)

• Manages data within a database
• Enables data management tasks like creation and querying

Normalization

• Organizing a database to reduce redundancy
• Improving data integrity

Foreign Key

• A field in one table that links to a primary key in another table

Primary Key

• Unique attribute used for identifying a record within a table

Candidate Key

• An attribute that could potentially serve as a primary key

Entity

• An object which data can be stored about within a database

Field

• A column in a database table
• Representing an attribute of an entity

Record

• A single row in a table
• Contains data about one instance of an entity

Security in DBMS

• Authentication
• Backups
• Encryption
• Access control rights

DDL (Data Definition Language)

• Defines database structures
• Includes commands for creating and altering tables

SQL (Structured Query Language)

• Language used for managing and manipulating relational databases

Truncate Command

• Removes all records from a table
• Retains the table structure

Software Licensing

• Legal means to use, copy, or distribute software

Open Source Software

• Software with source code available for anyone to modify or distribute

Shareware

• Software offered on a trial basis
• Requires payment for continued use

Commercial Software

• Software sold for a fee
• Not freely redistributable

Artificial Intelligence (AI) Applications

• Facial recognition
• Natural language processing
• Self-driving technologies

Ethics in Computing

• Standards guiding professional conduct
• Integrity in computer science practice

Copyright

• Legal rights to ownership and control over creative works

Intellectual Property Rights

• Rights protecting creators' inventions and creations

Hacking

• Unauthorized access to a system with malicious intent

Phishing

• Fraudulent attempts to obtain sensitive information
• Pretending to be a trustworthy entity

Malware

• Malicious software designed to harm or exploit any programmable device

Spyware

• Software that secretly monitors user activity
• Collects personal information

Data Redundancy

• Unnecessary duplication of data in a database

Data Consistency

• Ensured through relational databases that handle updates uniformly

Referential Integrity

• Rules to maintain consistency between related tables in a database

Tuple

• A record in a database table (a row)

Field Name

• The name of a column in a table

Data Type

• Specifies the kind of values that can be stored in a column

Backup and Recovery Procedures

• Processes to create backups
• Restoring data after a failure