Page 1: Data Representation Fundamentals
This page introduces key concepts in data representation for Edexcel Computer Science Paper 1 revision.
ASCII (American Standard Code for Information Exchange)
ASCII is a digital coding system used to represent letters, numbers, and symbols, facilitating text transfer between computers.
Definition: ASCII stands for American Standard Code for Information Exchange, used for transferring text across computers.
Colour Depth
Colour depth refers to the number of bits used to represent each pixel's colour in an image.
Example: A 3-bit colour depth can represent 2³ = 8 colours.
Highlight: The formula for calculating possible colours is 2ⁿ, where n is the number of bits.
File Size Calculation for Images
To determine an image's file size, multiply the image dimensions by the colour depth.
Formula: File size (bits) = width (pixels) × height (pixels) × colour depth (bits)
Pixels and Image Resolution
Pixels are the smallest units of a digital image, while image resolution refers to the total number of pixels.
Definition: A pixel is the smallest identifiable area of an image.
Formula: Image resolution (dpi) = width (pixels) × height (pixels)
Sound Wave Components
The guide explains key elements of sound waves, including amplitude, sample rate, sample frequency, and sample resolution.
Vocabulary:
- Amplitude: Height of the soundwave
- Sample rate & frequency: Number of samples taken per second (Hertz)
- Sample resolution: Storage space needed for acquired samples
File Size Calculation for Sound
To calculate sound file size, multiply sampling frequency, bit depth, and length.
Formula: File size (bits) = Sampling frequency × bit depth × length
