Advanced Data Representation Concepts
This page builds upon the previous concepts, introducing hexadecimal notation and exploring character sets and image representation in digital systems.
The hexadecimal number system is explained as a base-16 system, using digits 0-9 and letters A-F. A conversion table is provided, showing the relationships between denary, hexadecimal, and binary representations for numbers 0 to 15.
Highlight: Hexadecimal is commonly used in computing as it provides a more compact representation of binary data.
The document then transitions to character sets, introducing three main types:
- ASCII (American Standard Code for Information Interchange)
- Extended ASCII
- Unicode
Definition: A character set is a defined list of characters recognized by computer hardware and software.
ASCII is described as a 7-bit encoding system, capable of representing 128 characters. The types of characters included in ASCII are listed, such as control codes, punctuation symbols, upper and lowercase letters, and numeric digits.
Vocabulary: Extended ASCII - An 8-bit encoding system that expands the original ASCII set to include 256 characters, allowing for special characters and accents used in various languages.
Unicode is presented as a more comprehensive character encoding standard:
Highlight: Unicode uses 16 bits, allowing for over 65,000 characters, which enables support for a wide range of languages including Chinese, Hindi, and Korean.
The document then shifts focus to image representation in digital systems. Key concepts introduced include:
- Pixels (picture elements)
- Color depth
- Image resolution
Definition: Color depth refers to the number of bits used to represent the color of a single pixel in an image.
The relationship between color depth and the range of available colors is explained. The concept of image resolution is introduced, defined as the number of pixels per inch (PPI) or dots per inch (DPI).
Example: An image with dimensions 1000x800 pixels and a color depth of 4 bits per pixel would have a file size of 400,000 bytes (about 400KB).
The page concludes with an explanation of how to calculate image file sizes based on dimensions and color depth, providing a practical application of the concepts covered.
This comprehensive coverage of advanced data representation concepts provides students with a solid understanding of how different types of data are encoded and stored in computer systems, which is essential knowledge for GCSE Computer Science.
