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Topic 2: Data

7 dot points across 7 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

Why do computers use binary, and how many different states can a binary pattern of a given length represent?

Understand that computers use binary to represent data (numbers, text, sound, graphics) and program instructions, and determine the maximum number of states that can be represented by a binary pattern of a given length.
A focused answer to Edexcel GCSE Computer Science 2.1.1, covering why computers use binary to represent all data and instructions, and how to calculate the maximum number of states a binary pattern of a given length can represent.
8 min answer →

How do you add two binary numbers, apply binary shifts, and what is overflow?

Add together two positive binary patterns, apply logical and arithmetic binary shifts, and understand the concept of overflow in relation to the number of bits available to store a value.
A focused answer to Edexcel GCSE Computer Science 2.1.4 and 2.1.5, covering binary addition of two positive patterns, logical and arithmetic binary shifts, and the concept of overflow when a result needs more bits than are available.
9 min answer →

How do computers encode characters using 7-bit ASCII?

Understand how computers encode characters using 7-bit ASCII.
A focused answer to Edexcel GCSE Computer Science 2.2.1, covering how computers encode characters using a character set, the 7-bit ASCII system, its 128 codes, and the ordering of letters and digits.
8 min answer →

How is data storage measured in binary multiples, and why and how is data compressed?

Understand that data storage is measured in binary multiples (bit, nibble, byte, kibibyte, mebibyte, gibibyte, tebibyte), construct expressions to calculate file sizes and data capacity, and understand the need for and methods of compression (lossless, lossy).
A focused answer to Edexcel GCSE Computer Science 2.3.1 and 2.3.2, covering the binary storage multiples (bit, nibble, byte, kibibyte up to tebibyte), file-size and capacity calculations, and lossy and lossless compression.
9 min answer →

Why is hexadecimal used, and how do you convert between hexadecimal and binary?

Understand why hexadecimal notation is used and convert between hexadecimal and binary.
A focused answer to Edexcel GCSE Computer Science 2.1.6, covering why hexadecimal notation is used as a shorthand for binary and how to convert between hexadecimal, binary and denary.
8 min answer →

How are bitmap images and sampled sound represented in binary, and what limits this representation?

Understand how bitmap images are represented in binary (pixels, resolution, colour depth), how analogue sound is represented in binary (amplitude, sample rate, bit depth, sample interval), and the limitations of binary representation when constrained by the number of available bits.
A focused answer to Edexcel GCSE Computer Science 2.2.2, 2.2.3 and 2.2.4, covering bitmap images (pixels, resolution, colour depth), sampled sound (amplitude, sample rate, bit depth, sample interval), and the limitations of binary representation.
10 min answer →

How are signed integers represented in two's complement, and how do you convert between denary and 8-bit binary?

Understand how computers represent and manipulate unsigned integers and two's complement signed integers, and convert between denary and 8-bit binary numbers (0 to 255, and -128 to +127).
A focused answer to Edexcel GCSE Computer Science 2.1.2 and 2.1.3, covering unsigned and two's complement signed integers and converting between denary and 8-bit binary (0 to 255 and -128 to +127).
9 min answer →