Data Representation Digital Technologies

ASCII

A system where each character is stored as a number, like A = 65.

"A"

Character with ASCII value 65 (capital A).

"a"

Character with ASCII value 97 (lowercase a).

"0"

Character with ASCII value 48 (the digit zero).

Text in computers

Text is stored using ASCII codes that map characters to numbers.

Pixel

The smallest dot in an image, each with its own colour.

Image resolution

How many pixels are in an image; more pixels means more detail.

RGB

A colour model using Red, Green, and Blue light to make colours.

RGB value range

Each RGB colour channel can have a value between 0 and 255.

Black pixel

A pixel where R=0, G=0, B=0; no light means black.

White pixel

A pixel where R=255, G=255, B=255; full light = white.

Red pixel

A pixel with R=255, G=0, B=0; bright red.

Green pixel

A pixel with R=0, G=255, B=0; pure green light.

Blue pixel

A pixel with R=0, G=0, B=255; pure blue light.

Colour depth

The number of bits used to store a pixel’s colour.

8-bit colour

Uses 8 bits to store colour; allows 256 possible colours.

24-bit colour

Uses 24 bits total (8 per RGB); allows over 16 million colours.

Sound sampling

Measuring sound regularly to convert it into digital data.

Sampling rate

How many samples are taken per second (higher = better sound).

Bit depth (audio)

How many values each sound sample can store (e.g. 16-bit = 65,536).

High sampling rate

More samples per second, capturing more sound detail.

Low bit depth

Fewer levels of sound per sample, giving lower audio quality.

Binary

A number system using only 0s and 1s; used in all digital tech.

Why binary is used

Computers use binary because they only detect on/off (1/0) signals.

Data representation

How computers store data like text, images, and sound using numbers.

What is ASCII stored in, in computers?

ASCII is stored as binary code, where each character is represented by a unique 7 or 8-bit binary number, allowing computers to interpret and display text.