Hexadecimal

Hexadecimal Numbers

Hexadecimal is faster for humans to process than binary. Hexadecimal allows us to find errors more easily. Hexadecimal is used in every computer system.

Hexadecimal

Hexadecimal or hex uses 16 different symbols for each place.
- This means hexadecimal is a base-16 numerical system.
Hexadecimal uses the digits 0-9, then A-F:
- A = 10 in denary, B = 11 , C = 12, D = 13 and so on.
Each digit's place value is multiplied by 16 as we move from right to left.

Advantages

An 8-bit binary number can be represented by two hexadecimal digits.
- This means you can reduce processing time with hexadecimal than with binary.
Hex is easier and faster to write two digits than the full binary sequence.
It is easier for a human to process hexadecimal than binary.

Using hexadecimal

Hexadecimal is used extensively in programming languages such as:
- Machine code.
- Assembly.
Hex can be used during the debugging stage of writing programs as it is easy to process by humans.
Hex can represent numbers stored in a CPU's registers or in main memory.

Using Hexadecimal

Hexadecimal is used in HTML to display colour on websites and to form unique MAC addresses for devices connected to a network.

HTML colours

In HTML, colours are defined by how much red, green and blue (RGB) there is on a scale of 0 to 255.
- 0 to 255 is the range of numbers that can be represented as a single byte.
- This means we use 2 hexadecimal digits to represent each RGB value.
HTML colour codes start with a hash symbol followed by 3 pairs of hexadecimal numbers like #00FF00.

HTML colours

We can break down the HTML colour code #00FF00 in the following way:
- The red value is 00, which means we have 0 units of red.
- The green value is FF, so we have 255 units of green.
- The blue value is 00, so we have 0 units of blue.
The colour code #00FF00 corresponds to a bright green colour.

MAC addresses

A MAC address is a number that uniquely identifies a networked device.
A MAC address is made up of 48 bits which are shown as 6 groups of 2 hexadecimal digits:
- NN-NN-NN-DD-DD-DD or NN:NN:NN:DD:DD:DD
The first 6 hex digits identify the device manufacturer.
The second 6 hex digits identify the serial number of the device.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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