Data Representation: Number Systems, Media, and Compression

Comprehensive vocabulary flashcards covering computer science number systems (denary, binary, hexadecimal), arithmetic operations, data representations of text, audio, and images, as well as data storage units and file compression techniques.

Binary

A base-$2$ numbering system that uses only two digits, $0$ and $1$, which corresponds to the on and off electrical states of computer transistors.

Bit

Short for binary digit; the smallest unit of measurement in computer data storage, representing a single $0$ or $1$.

Transistor

A tiny electronic switch inside a computer that exists in one of two states: on (electricity flowing, represented as $1$) or off (no electricity flowing, represented as $0$).

Denary Number System

Also known as the decimal system; a base-$10$ numbering system that uses $10$ digits ($0, 1, 2, 3, 4, 5, 6, 7, 8, 9$) where each digit position represents a power of $10$.

Hexadecimal Number System

A base-$16$ numbering system that uses $16$ digits: $0$ through $9$ and letters $A$ through $F$, where $A$ represents $10$, $B$ represents $11$, up to $F$ representing $15$.

Nibble

A group of $4\text{ bits}$ of binary data, equivalent to one hexadecimal digit.

Byte

A group of $8\text{ bits}$ of binary data.

Least Significant Bit (LSB)

The rightmost bit in a binary number, representing the lowest place value ($2^0$).

Overflow Error

An error that occurs when the result of a binary operation exceeds the maximum value that can be represented (such as exceeding $255$ in an $8\text{-bit}$ register) because a carry bit cannot be accommodated.

Binary Shift

The process of multiplying or dividing a binary number by moving all bits a specified number of positions to the left or to the right.

Logical Binary Shift to the Left

A binary shift where bits at the end of the register are lost and zeros are added at the right; each single shift position to the left is equivalent to multiplying the value by $2$.

Logical Binary Shift to the Right

A binary shift where bits at the beginning of the register are lost and zeros are added at the left; each single shift position to the right is equivalent to dividing the value by $2$.

Two's Complement

A method used to represent signed integers in binary form, where the leftmost bit represents the sign ($0$ for positive and $1$ for negative).

Character Set

A collection of characters and their corresponding binary codes that a computer uses to represent text.

ASCII

American Standard Code for Information Interchange; a character set that assigns a unique $7\text{-bit}$ binary code to each character, limited to English characters, digits, punctuation, and control characters.

Unicode

A character encoding standard using a variable-length scheme across multiple bytes to represent a vast range of symbols, emojis, and characters from different global languages.

Sampling

The process of converting an analogue sound wave into digital form by measuring the sound wave at regular intervals and turning those measurements into binary data.

Sample Rate

The number of audio samples taken per second, measured in Hertz ($\text{Hz}$); higher sample rates yield a more accurate audio representation but increase file size.

Sample Resolution

The number of bits allocated per audio sample, which determines the precision, level of detail, and accuracy of each measurement.

MIDI

Musical Instrument Digital Interface; an audio file format that stores instructions on how sounds should be played (including pitch, note duration, volume, and instrument type) rather than recording actual sound waves.

MP3

A lossy compressed digital audio file format that stores an actual acoustic recording of sound, typically recorded via a microphone.

Bitmap Image

A digital image made up of a grid of tiny coloured dots called pixels, where each pixel is stored as a binary code.

Image Resolution

The total number of pixels in an image (width $\times$ height); higher resolution produces a sharper, more detailed image but demands more storage space.

Colour Depth

The number of bits allocated to represent each colour in an image; higher colour depth allows a greater variety of colours ($2^n$) and more realistic images at the expense of larger file sizes.

Kibibyte (KiB)

A binary unit of data storage measurement equal to $1024\text{ bytes}$ or $2^{10}\text{ bytes}$.

Mebibyte (MiB)

A binary unit of data storage measurement equal to $1024 \times 1024\text{ bytes}$ ($1{,}048{,}576\text{ bytes}$) or $2^{20}\text{ bytes}$.

Lossless Compression

A compression method that reduces file size without permanently removing any original data, allowing the file to be fully restored using indexing and encoding algorithms.

Lossy Compression

A compression method that reduces file size by permanently discarding less critical data (such as minor details in images and sound), which cannot be recovered.

Run-Length Encoding (RLE)

A lossless compression technique that replaces consecutive sequences of repeated identical characters with a code indicating the character and the count of its repetitions.

Memory Dump

A record of the contents of a computer's memory taken at the time of a crash or error, often reviewed in hexadecimal to identify specific memory addresses and values.