CAIE IGCSE Computer Science Flashcards

Flashcards for CAIE IGCSE Computer Science - Summarized Notes On The Theory Syllabus

Binary System

Base 2 number system with values 0 and 1, where 0 represents OFF and 1 represents ON. The most left bit is called the MSB (Most Signi cant Bit)

Denary System

Base 10 number system with values from 0 to 9.

Hexadecimal (Hex)

Base 16 number system with values from 0 to 9 followed by A to F, where A represents 10 and F represents 15.

MSB

Most Significant Bit; refers to the leftmost bit in a binary number.

Overflow (Binary Calculations)

When adding two binary values, if the solution exceeds the limit of given bits, the extra bit is called overflow, indicating insufficient memory to store the result.

Logical Shift

Moving a binary value to the left or right, with the emptied bit becoming 0.

Two’s Complement

A method used to represent negative values in binary, where the MSB is replaced from 128 to -128.

ASCII

A standard character set that consists of 7-bit code representing letters, numbers, and characters, along with 32 control codes.

Unicode

A character encoding standard that supports multiple languages and more data, using up to four bytes per character. The rst 128 values are the same as ASCII.

Sampling Resolution (Bit Depth)

The number of bits per sample in digital audio, affecting the accuracy and memory usage of the sound file.

Sampling Rate

The number of sound samples taken per second, measured in Hertz (Hz), affecting the accuracy of the sound representation.

Colour Depth

The number of bits representing each colour in a bitmap image.

Image Resolution

The number of pixels that make up an image.

Pixelated

When a bitmap image is ‘ blurry ‘ or ‘ zzy ’ due to having a low amount of pixels in it or when zoomed

IECB System

1 kibibyte (1KiB) = 2^10 = 1024 bytes;1 mebibyte (1MiB) = 2^20 = 1 048 576 bytes; 1 gibibyte (1GiB) = 2^30 = 1 073 741 824 bytes; 1 tebibyte (1TiB) = 2^40 = 1 099 511 627 776 bytes; 1 pebibyte (1PiB) = 2^50 = 1 125 899 906 842 624 bytes

Conventional System

1 kilobyte (1KB) = 10^3 = 1 000 bytes; 1 megabyte (1MB) = 10^6 = 1 000 000 bytes; 1 gigabyte (1GB) = 10^9 = 1 000 000 000 bytes; 1 terabyte (1TB) = 10^12 = 1 000 000 000 000 bytes; 1 petabyte (1PB) = 10^15 = 1 000 000 000 000 000 bytes

MIDI (Musical Instrument Digital Format)

A communications protocol that allows electronic musical instruments to interact with each other, stored as a series of commands but no actual music notes.

MP3

A file format that uses audio compression to reduce file size by removing sounds that the human ear cannot hear properly, using a lossy format.

MP4

A format that allows the storage of multimedia files, including music, videos, photos, and animations.

JPEG (Joint Photographic Experts Group)

A file format used to reduce photographic file sizes through compression, reducing the raw bitmap image by a factor between 5 and 15.

Lossless File Compression

File compression where all data bits from the original file are reconstructed after uncompression, important for files where data loss would be disastrous.

Run-Length Encoding (RLE)

A lossless compression technique that reduces the size of a string of adjacent, identical data by encoding it into two values: the number of identical data items and the code of the data item.

Lossy File Compression

A file compression algorithm that eliminates unnecessary data bits, reducing file quality and making it impossible to get the original file back after compression.

Data Packets

broken down data sent as multiple parts; structure usually includes a header (sender/receiver IP, sequence), payload (data), and trailer (end identifier, error-checking)

Packet Switching

Method of data transmission where data is broken into multiple packets, sent independently, and reassembled at the receiver's computer.

Simplex Data Transmission

Data transmission in one direction only.

Half-Duplex Data Transmission

Data transmission in both directions, but not simultaneously.

Full-Duplex Data Transmission

Data transmission in both directions simultaneously.

Serial Data Transmission

Data sent one bit at a time over a single wire.

Parallel Data Transmission

Data of several bits (1 byte) sent down several wires at the same time.

USB (Universal Serial Bus)

An asynchronous serial data transmission method using a four-wire shielded cable.

Parity Checks

Error detection method using the number of 1-bits in a byte (even or odd parity).

Parity Blocks

Used to overcome the limitations of parity bits, changes in bits would be identi ed through the rows and columns

Checksum

Error detection method where the sender calculates a value using a specific algorithm, and the receiver recalculates and compares it to verify data integrity.

Echo Check

Error detection method where the receiver sends the data back to the sender for verification.

Check Digits

Digits calculated from all the other digits in the data (ex-codes) used to identify mistyping errors

Automatic Repeat Requests (ARQs)

Error detection method using acknowledgements and timeouts to ensure data is received correctly.

Encryption

Process of turning data into an unreadable form to protect it from unauthorized access.

Plaintext

Original data before encryption.

Ciphertext

Text produced after encryption.

Symmetric Encryption

Encryption using the same key for both encryption and decryption.

Asymmetric Encryption

Encryption using a public key and a private key.

CPU (Central Processing Unit)

The central component of a computer system, containing the Arithmetic and Logic Unit (ALU) and Control Unit.

ALU (Arithmetic Logic Unit)

Part of the CPU that carries out logic and arithmetic calculations.

Registers

CIR (Current instruction register), MAR (Memory address register), MDR (Memory data register), PC (Program counter), ACC (Accumulator).

Instruction Set

A list of all the commands that a CPU can process.

Overclocking

Using a clock speed higher than the computer was designed for.

Cache Memory

A small, fast memory within the CPU that stores frequently used instructions and data.

OCR (Optical Character Recognition)

A software which converts scanned documents into a text file format.

CAD (Computer-Aided Design)

Used in 3D scanners or to design a working model.

Barcode

A series of dark and light parallel lines of varying thicknesses representing numbers 0-9.

QR (Quick Response) Code

Another type of barcode that is Made up of a matrix of lled-in dark squares on a light background

ADC (Analogue-to-Digital Converter)

Converts physical values into digital

Actuators

The convert electrical signals to mechanical processes.

DLP (Digital Light Projector)

A projector that Uses millions of micromirrors which determines the resolution of the image

Primary Storage

Memory that The CPU directly accesses.

Secondary Storage

Memory that the CPU does not directly accesses.

RAM (Random Access Memory)

Volatile/temporary memory which that store; data, files It can be written to or read from, and the contents of the memory can be changed

ROM (Read Only Memory)

Non-volatile/permanent memories (contents remain even when ROM is turned o ) Used to store start-up instructions (basic input/output systems) Data/contents of a ROM chip can only be read and cannot be changed

O -Line Storage:

CD/DVD Disks with laser(red) light that is used to read and write data on the surface of the disk. A thin layer of metal alloy is used to store data.

Cloud Storage

A method of data storage where data is stored on remote servers The same data is stored on more than one server in case of maintenance or repair, allowing clients to access data at any time.

Embedded System

A combination of hardware and software is designed to carry out a speci c set of tasks.

NIC (Network Interface Card)

A network interface card (NIC) is needed to allow a device to connect to a network (such as the Internet).

MAC

Media Access Control is 48 bits which are shown as six groups of hexadecimal digits indicating the device serial number

IP

Two types of IP addresses: static and dynamic where the network allocates IP addresses

Operating Systems

Systems designed to establish communication between the user and the computer

WIMP

Windows, Icons, Menu, and Pointing Devices.

BIOS (Basic Input/Output System)

It Tells the computer the location of the OS in the storage

High-Level Languages

Easier to read and understand as the language is closer to human language

Low-Level Languages

Refer to machine code; Binary instructions that the computer understands

Compiler

Translates a program written in a high-level language into machine code Used without compiler Executable file of machine code produced

Interpreter

Executes a high-language program a statement at a time No executable file of machine code produced

Assembler

Translates a low-level language program into machine code Executable file of machine code produced

IDEs (Integrated Development Environments)

An IDE would usually have these features - Code Editor Translator Debugger Error Reports Auto-Completion and Auto-Correction Auto-Documenter Pretty Printing

System Software

These are a set of programs which control and manage the operations of hardware. gives a platform for other software to run

Application Software

Allows a user to perform speci c tasks using the computer’s resources

Utility Software

Computer users have access to utility programs as part of system software Utility programs can be initiated by the user or run in the background without user input

Internet

Uses transmission protocols such as TCP and IP (Internet Protocols) Allows the user to communicate with other users via chat, email, calling and more Worldwide Collection of Interconnected Networks and Devices

World Wide Web (WWW)

Collection of webpages and other information on websites Uses HTTP(S) protocols that are written using Hypertext Mark-up Language (HTML) URLs (Uniform Resource Locator) are used for the location of the web pages

Cookies

Small files stored on the user’s computer They are used to track data about the users and auto fill forms or give suggestions accordingly

Blockchain Network

Network that involves several interconnected computers where the transaction data is stored Hacking isn’t possible here as transaction details would be sent to all the computers, and the data can’t be changed without the consent of all the network members

Malware

Stands for Malicious Software. A few examples are - Virus, Ransomware, Adware, Trojan Horse, Spyware, Worms

Phishing

Attackers send legitimate-looking emails to bait the user into giving out their information.

SSL (Secure Socket Layer)

It is Set of rules used while communicating with other users on the internet.

Automated Systems

Are a combination of software and hardware designed to function without human intervention.

Robotics

It is branch of computer science that combines robot design, construction and operation.

Artificial Intelligence AI

Is the branch of computer science that simulates intelligent human behaviour.