# Data Representation

## Computational Thinking

We may think that computer “think” and that they outsmart humans “just like that”. However that’s not the case, computers do exactly what we humans tell them to do, or better said, what we program them to do. Once programmed a computer can only execute problems and produce solutions more efficiently than humans. Computational thinking …

## Number Systems

Candidates should be able to: convert positive denary whole numbers (0-255) into 8-bit binary numbers and vice versa add two 8-bit binary integers and explain overflow errors which may occur convert positive denary whole numbers (0-255) into 2-digit hexadecimal numbers and vice versa convert between binary and hexadecimal equivalents of the same number explain the …

## Character Sets

Candidates should be able to: explain the use of binary codes to represent characters explain the term character set describe with examples (for example ASCII and Unicode) the relationship between the number of bits per character in a character set and the number of characters which can be represented. How are binary codes used to …

## Computer Instructions

Candidates should be able to: explain how instructions are coded as bit patterns explain how the computer distinguishes between instructions and data. How are program instructions coded? Machine code instructions are binary numbers and are coded as bit patterns, for example, a 16 bit machine code instruction could be coded as 001010101101001011. In machine code …

## Data Units

Candidates should be able to: define the terms bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte understand that data needs to be converted into a binary format to be processed by a computer. Data units in computer systems Bit This is a single unit of memory and can only store 2 possible binary values, either 0 …

## Image Representation

Candidates should be able to: explain the representation of an image as a series of pixels represented in binary explain the need for metadata to be included in the file such as height, width and colour depth discuss the effect of colour depth and resolution on the size of an image file. How can an …

## Sound Representation

Candidates should be able to: explain how sound can be sampled and stored in digital form explain how sampling intervals and other considerations affect the size of a sound file and the quality of its playback. How can sound be sampled and stored in digital form? A microphone converts sound waves into voltage changes. If …

## Converting Decimal to Binary

Decimal Numbering System Decimal is a base 10 numbering Binary Numbering System Binary is a base 2 numbering system which is made up of two numbers: 0 and 1.  0 means OFF and 1 means ON.  The computer’s central processing unit (CPU) only recognizes these two states – ON and OFF.  It is the foundation …

Hexadecimal Numbering System Hexadecimal is a base 16 numbering system which is made up of 16 digits: 0 – 9 and six more, which is A through F. Uses of Hexadecimal Hexadecimal numbering system is often used by programmers to simplify the binary numbering system.  Since 16 is equivalent to 24, there is a linear …

Hexadecimal Numbering System Hexadecimal is a base 16 numbering system which is made up of 16 digits: 0 – 9 and six more, which is A through F. Uses of Hexadecimal Hexadecimal numbering system is often used by programmers to simplify the binary numbering system.  Since 16 is equivalent to 24, there is a linear …

Decimal Numbering System Decimal is a base 10 numbering system which is made up of 10 numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.  It is the most commonly used numbering system.  The reason behind that is convenience.  We have 10 fingers that we use for counting, so it is easier …

Hexadecimal Numbering System Hexadecimal is a base 16 numbering system which is made up of 16 digits: 0 – 9 and six more, which is A through F. The table below shows how hexadecimal system works and its equivalent decimal number: Hexadecimal Decimal Hexadecimal Decimal 0 0 11 = (1 x 16) + 1 17 …

Binary Numbering System Binary is a base 2 numbering system which is made up of two numbers: 0 and 1.  0 means OFF and 1 means ON.  The computer’s central processing unit (CPU) only recognizes these two states – ON and OFF.  It is the foundation for all binary code, which is used in computer …

## Converting Binary to Decimal

Binary Numbering System Binary is a base 2 numbering system which is made up of two numbers: 0 and 1.  0 means OFF and 1 means ON.  The computer’s central processing unit (CPU) only recognises these two states – ON and OFF.  It is the foundation for all binary code, which is used in computer …

## Bitmap Image and Colour Depth Quiz

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## Colour Depth Gap Fill Exercise

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## Data Units Gap Fill Exercise

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## Data Units Multi-Choice Quiz

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## Colour Mapping and Direct Colour

Pupil Resources – EXTENSION TOPIC What is the difference between Colour Mapping and Direct Colour? Colour mapping With low colour depths (up to 8-bit) it is practical to map every colour to a binary code. 1-bit colour mapping – (2 colours) monochrome, often black and white. 2-bit colour mapping – (4 colours) CGA – used …

## Instructions

Candidates should be able to: explain how instructions are coded as bit patterns explain how the computer distinguishes between instructions and data. How are program instructions coded? Machine code instructions are binary numbers and are coded as bit patterns, for example, a 16 bit machine code instruction could be coded as 001010101101001011. In machine code …

## Sound – Quality, Size & Storing Solutions

Candidates should be able to: explain how sound can be sampled and stored in digital form explain how sampling intervals and other considerations affect the size of a sound file and the quality of its playback. How can sound be sampled and stored in digital form? A microphone converts sound waves into voltage changes. If …