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3.3 Fundamentals of data representation

8 dot points across 8 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do computers add binary numbers and shift the bits?

Add binary numbers up to and including three 8-bit numbers, recognise overflow, and apply logical and arithmetic binary shifts.
A focused answer to AQA GCSE Computer Science 3.3.2, covering binary addition of up to three 8-bit numbers, overflow, and logical and arithmetic binary shifts.
8 min answer →

How are letters and symbols stored as numbers?

Understand how characters are represented using ASCII and Unicode character sets, and the effect of the character set on storage and the range of characters.
A focused answer to AQA GCSE Computer Science 3.3.5, covering how characters are represented using ASCII and Unicode, and the effect of the character set on storage and the range of characters.
7 min answer →

How do we make files smaller, and what is the trade-off?

Understand why data is compressed, and the difference between lossy and lossless compression including run-length encoding and Huffman coding.
A focused answer to AQA GCSE Computer Science 3.3.8, covering why data is compressed and the difference between lossy and lossless compression, including run-length encoding and Huffman coding.
8 min answer →

Why is hexadecimal useful, and how do we convert to and from it?

Understand hexadecimal, convert between binary, denary and hexadecimal, and explain why hexadecimal is used.
A focused answer to AQA GCSE Computer Science 3.3.3, covering hexadecimal, converting between binary, denary and hexadecimal, and why hexadecimal is used.
8 min answer →

Why do computers use binary, and how does it relate to the numbers we use?

Understand the binary, denary and hexadecimal number bases, why computers use binary, and convert between binary and denary.
A focused answer to AQA GCSE Computer Science 3.3.1, covering the binary, denary and hexadecimal number bases, why computers use binary, and how to convert between binary and denary.
8 min answer →

How is a picture stored as binary?

Understand how a bitmap image is represented using pixels and colour depth, the effect of resolution and colour depth on quality and file size, and the role of metadata.
A focused answer to AQA GCSE Computer Science 3.3.6, covering how bitmap images are represented using pixels and colour depth, the effect of resolution and colour depth on quality and file size, and metadata.
8 min answer →

How is sound stored as binary?

Understand how analogue sound is sampled to be stored digitally, the effect of sample rate and bit depth on quality and file size, and calculate sound file sizes.
A focused answer to AQA GCSE Computer Science 3.3.7, covering how analogue sound is sampled for digital storage, the effect of sample rate and bit depth on quality and file size, and calculating sound file sizes.
8 min answer →

How do we measure the amount of data a computer stores?

Know that data is stored in bits and bytes, the units from bit to terabyte, and calculate file sizes and storage requirements.
A focused answer to AQA GCSE Computer Science 3.3.4, covering bits and bytes, the units from bit to terabyte, and calculating file sizes and storage requirements.
7 min answer →