1.1.3 | NUMBER SYSTEMS
Topics from the Cambridge IGCSE (9-1) Computer Science 0984 syllabus 2023 - 2025.
HOW IS HEXADECIMAL USED IN COMPUTER SYSTEMS
Hexadecimal (HEX) is a beneficial method of data representation for several reasons. Firstly, it is a more compact notation than binary for representing large numbers. Each digit in a HEX number represents 4 bits, which is more concise than the 8 bits required for each digit in binary. This makes HEX an efficient way to represent large amounts of data, particularly in for easy human interpretation.
  • HEX is a widely recognized notation in digital systems, making it easier to communicate and interpret data across different systems and applications. Many devices and systems use HEX notation to display and transmit data, particularly in computer networking and telecommunications.
  • HEX is easier for humans to read than binary, since HEX numbers can be represented using a smaller number of digits than binary numbers. This makes it easier to interpret and work with HEX data, particularly for non-technical users who may not be familiar with binary notation.
  • HEX takes up less screen space than binary, which means it can be used on small displays such as washing machines to give error codes or other status information. HEX allows for concise, easy-to-read displays that can be used in a variety of applications and devices, making it a valuable tool for data representation in digital systems.

Hexadecimal (HEX) is used in several areas within a computer system, including:
  • Memory Addressing: Computer memory is typically organized as a series of individual addressable locations, each of which contains a binary value. These memory locations are often represented using HEX notation, which makes it easier for programmers and system administrators to work with large amounts of memory data.
  • Programming: Many programming languages and development tools use HEX notation to represent binary values, such as machine instructions or memory addresses. HEX provides a more compact and convenient way to work with binary data in programming environments.
  • Error Codes: In many computer systems, error codes are used to indicate specific system or software errors. These error codes are often displayed using HEX notation, which provides a concise and easy-to-read way to communicate complex error information to users.
  • Network Addresses: In computer networking, HEX notation is often used to represent IP addresses and other network addresses. This allows network administrators to easily interpret and work with network addressing data in a concise and standardized format.
  • Graphics: In computer graphics, HEX notation is used to represent colours using the RGB (Red-Green-Blue) colour model. Each colour component is represented using a 2-digit HEX number, allowing for precise and efficient representation of colour data.

HEX is used in several important areas within a computer system, providing a valuable tool for representing and working with binary and other data in a standardized and efficient manner
HEXADECIMAL COLOUR REPRESENTATION
Just as numbers and letters are represented with Binary, so are images. To a computer an image is nothing more than a series of ones and zeros which allow the display of pixels in various colours.

To aid human reading of different colour codes, colours are commonly represented in Hexadecimal using the RGB Red Green Blue system. For example the chart below shows how pure blue is represented using HEX, the HEX code for pure blue is #00 00 FF, meaning it has zero red components, zero green components and the maximum amount of Blue components.
Picture
A brief colour chart for some of the colours represented in hexadecimal.
Most software that allows you to manipulate images or colours will allow you to select colours by their HEX or RGB values.

​Remember: Hex is used for our benefit to make it easy for use to see and work with, but the computer still deals with colour in binary format
1: What is the benefit of using hexadecimal notation over binary notation for representing large numbers?
2: Why is hexadecimal notation commonly used in computer programming?
3: How are memory addresses typically represented using hexadecimal notation?
4: What is the purpose of using hexadecimal notation for error codes in computer systems?
5: How is hexadecimal notation used to represent IP addresses and other network addresses in computer networking?
6: How is hexadecimal notation used in representing Unicode characters in computer systems?
7: What is the relationship between hexadecimal notation and the RGB colour model?
8: How is hexadecimal notation used to represent machine instructions in computer systems?
NAVIGATION
1.1.1 NUMBER SYSTEMS | Why Computers use Binary
1.1.2 NUMBER SYSTEMS | Binary, Hex and converting between number systems 
1.1.3 NUMBER SYSTEMS | Benefits of Hex
1.1.4 NUMBER SYSTEMS | Binary addition and Overflow
1.1.5 NUMBER SYSTEMS | Binary Shifts
1.1.6 NUMBER SYSTEMS | Negative Number representation, Two's Complement
1.2.1 TEXT, SOUND AND IMAGES | How Computer represent Text
1.2.2 TEXT, SOUND AND IMAGES | How Computers represent Sound
1.2.3 TEXT, SOUND AND IMAGES | How Computers represent Images
1.3.1 STORAGE AND COMPRESSION | How data storage is measured
​1.3.2 STORAGE AND COMPRESSION | Calculating image and sound file size
​1.3.3 STORAGE AND COMPRESSION | Purpose of Data Compression
​1.3.4 STORAGE AND COMPRESSION | Lossy and Lossless, how files are compressed
TOPIC 1 KEY TERMINOLOGY
TOPIC 1 ANSWERS
TOPIC 1 TEACHER RESOURCES (CIE)
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