Cambridge International GCSE Computer Science - Data Representation

Vocabulary flashcards covering data representation concepts including binary arithmetic, hexadecimal conversion, two's complement, logical shifts, media storage, file size calculations, and compression.

Binary System

A base-2 number system that uses digits 0 and 1, where the smallest unit is 1 bit.

Denary System

A base-10 number system used for everyday human counting, which uses digits 0 to 9.

Hexadecimal System

A base-16 number system that uses digits 0-9 and letters A-F to represent values in 4-bit binary groups.

Overflow

An error condition that happens when the result of a binary calculation is too large to fit in the available number of bits.

Logical Left Shift

An operation that shifts bits to the left, inserts 0 on the right, and multiplies the value by 2 if no important bit is lost.

Logical Right Shift

An operation that shifts bits to the right, inserts 0 on the left, and divides the value by 2 while ignoring any remainder.

Two's Complement

A method used to represent negative integers in fixed-length binary by writing the positive value, inverting all bits, and adding 1.

Sign Bit

The leftmost bit in a signed binary number, where 0 represents a positive value and 1 represents a negative value.

Character Set

A collection of characters where each character is assigned a unique numerical code that is stored in binary.

ASCII

A character set that uses 7 bits to represent 128 distinct characters.

Unicode

A character set that supports many languages, symbols, and emoji, often using UTF-8 with a variable number of bytes.

Colour Depth

The number of bits used per pixel in a bitmap image, which determines the total number of available colours ($2^n$).

Resolution

The property of a bitmap image that specifies the total number of pixels.

Metadata

Information stored inside an image file that gives details such as width, height, and file type.

Sampling Rate

The number of measurements taken of an analogue sound wave every second during digital conversion.

Sample Resolution

The number of bits allocated to store each individual sound sample.

Stereo Audio

An audio format that uses two channels to store separate sound data for the left and right speakers.

Kibibyte (KiB)

A binary unit of data storage equal to $1,024\,\text{bytes}$.

Lossless Compression

A data compression technique where no data is removed, allowing the original file to be restored exactly (e.g., RLE, Huffman coding, ZIP).

Lossy Compression

A data compression technique where some data is permanently removed, meaning the original file cannot be restored perfectly (e.g., JPEG, MP3, MPEG).