Cambridge IGCSE Computer Science - Data Representation Revision

Vocabulary flashcards covering number systems, binary arithmetic, bit shifts, two's complement, media representations, storage calculations, and data compression techniques from the Cambridge IGCSE 0478 revision paper.

Binary number system

The base-2 numerical system using only the digits 0 and 1, used by computers to represent all data and instructions.

Hexadecimal

A base-16 number system using digits 0–9 and letters A–F to represent binary values in a more compact and readable format.

Overflow error

An error that occurs during binary arithmetic when the calculated result exceeds the maximum value or number of bits that the target register can store.

Logical left shift

A bitwise operation that moves every bit in a binary number to the left by a specified number of places, shifting zeros into the vacated positions on the right.

Logical right shift

A bitwise operation that moves every bit in a binary number to the right by a specified number of places, discarding bits that fall off and inserting zeros on the left.

Two's complement

A binary system used to represent signed integers, where the most significant bit possesses a negative weight to represent negative numbers.

ASCII

A character encoding standard that assigns a unique numerical code to represent text characters (for example, the letter 'A' is represented by denary 65).

Unicode

A universal character encoding standard developed to represent text, symbols, and scripts from all languages worldwide, overcoming the character set limitations of ASCII.

Sample rate

The number of audio samples taken per second when converting an analogue sound signal into digital data, measured in Hertz ($\text{Hz}$).

Sample resolution

The number of bits allocated to represent and store the amplitude of each individual audio sample.

Colour depth

The number of bits used to represent the colour of each individual pixel in a digital bitmap image.

Kibibyte (KiB)

A unit of digital data storage equivalent to exactly $1024$ bytes.

Mebibyte (MiB)

A unit of digital data storage equivalent to exactly $1024\text{ KiB}$.

Lossless compression

A data compression algorithm that reduces file size without discarding any data, enabling the original file to be reconstructed completely.

Lossy compression

A data compression method that reduces file size by permanently discarding unnecessary or less noticeable data, meaning the original cannot be fully reconstructed.

Binary number system

A base-2 numbering system consisting of only two digits (0 and 1) that computers use internally to process and store all data.

Hexadecimal

A base-16 numbering system that uses 16 distinct symbols (0 through 9 and A through F) to represent values, commonly used as a human-friendly shorthand for binary strings.

Overflow

An error condition that occurs during binary arithmetic when the result of an addition is too large to fit inside the designated register size (such as an 8-bit register).

Logical left shift

An operation where all bits in a binary sequence are moved to the left by a specified number of positions, multiplying the number by $2$ for each shifted place, while vacant places on the right are filled with zeros.

Logical right shift

An operation where all bits in a binary sequence are shifted to the right by a specified number of positions, dividing the number by $2$ for each place shifted, while bits falling off the right are discarded and vacant positions on the left are filled with zeros.

Two's complement

A mathematical representation used by computer systems to encode signed (both positive and negative) numbers in binary.

Minimum 8-bit two's complement value

The lowest denary value that can be represented using an 8-bit two's complement register, which is $-128$.

ASCII

A character encoding standard where every character is assigned a unique numerical value (such as the letter A having a denary value of $65$).

Unicode

A comprehensive character encoding standard developed to represent symbols, scripts, and characters across all global languages, resolving character set limitations found in ASCII.

Sample rate

The number of audio sound samples captured per unit time, measured in Hertz ($\text{Hz}$).

Sample resolution

The number of bits used to encode each audio sample in a sound file, determining the dynamic range and fidelity of the recording.

Colour depth

The number of bits allocated to represent the colour value of each individual pixel in a bitmap image.

Kibibyte (KiB)

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

Mebibyte (MiB)

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

Lossy compression

A data compression algorithm that reduces file size by permanently discarding unnecessary or less perceptible data, preventing the exact reconstruction of the original file.

Lossless compression

A data compression algorithm that reduces file size by encoding data efficiently without permanently removing any information, allowing the original data to be fully restored.