A bit is a single binary digit, either 0 or 1. A bit is the smallest unit of data a computer can store.

How many different states can a binary pattern of n bits represent?

A pattern of n bits can represent 2ⁿ different states. Each extra bit doubles the number of states.

How many different values can a 5-bit pattern represent?

A 5-bit pattern can represent 32 different values. Five bits give 2⁵ = 32 combinations.

What is the smallest number of bits needed to give a unique code to each of 50 students?

Six bits are needed, since 2⁶ = 64 codes is enough for 50 students. Five bits give only 32 codes, which is too few.

Edexcel GCSE Computer Science 1CP2

Computational Thinking

Topic overview Decomposition, abstraction and subprograms Algorithms, flowcharts and pseudocode Operators and trace tables Logic errors, test data and efficiency Searching and sorting algorithms Truth tables

Data

Topic overview Binary, states and unsigned integers Two's complement Binary addition, overflow and shifts Hexadecimal ASCII and the limits of binary representation Bitmap images Sound sampling Storage units, file sizes and compression

Computers

Topic overview Von Neumann architecture and the fetch-decode-execute cycle Secondary storage: magnetic, optical and solid state Embedded systems Operating systems Utility software and robust software Low-level and high-level languages and translators

Networks

Topic overview LANs, WANs and the structure of the internet Wired and wireless connectivity and network speed Network protocols The four-layer TCP/IP model Bus, star and mesh topologies Network security and protection

Issues and Impact

Topic overview Environmental impact of digital devices Personal data: privacy, ownership and consent Artificial intelligence, machine learning and robotics Intellectual property: copyright, patents, trademarks and licences Malware, hacking and social engineering Protecting digital systems and data

Problem Solving with Programming

Topic overview Readable code, debugging and testing Selection and loops in Python Data types, conversion, variables and constants String handling Lists, two-dimensional lists and records Keyboard input, screen output and CSV files Validation and authentication in Python Operators, functions and variable scope Turtle graphics

Data

Binary, states and unsigned integers

3 things to know
Paper 1

Overview

Why computers use binary, the number of states n bits can represent, unsigned integers from 0 to 255, place values, and worked conversions between denary and binary.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why do computers use binary to represent data and program instructions?

Key term

Which kinds of data does a computer store as binary?

Key term

What is a bit?

Questions from this subtopic

Each one with the model answer underneath.

1
Why do computers use binary to represent data and program instructions?
Model answer
A computer's circuits are built from transistors that act as switches with two states, on and off. The binary digits 1 and 0 map directly onto those two states.
2
Which kinds of data does a computer store as binary?
Model answer
A computer stores numbers, text, sound and images as binary. Program instructions are stored as binary patterns too.
3
What is a bit?
Model answer
A bit is a single binary digit, either 0 or 1. A bit is the smallest unit of data a computer can store.
4
How many different states can a binary pattern of n bits represent?
Model answer
A pattern of n bits can represent 2ⁿ different states. Each extra bit doubles the number of states.
5
How many different values can a 5-bit pattern represent?
Model answer
A 5-bit pattern can represent 32 different values. Five bits give 2⁵ = 32 combinations.
6
What is the smallest number of bits needed to give a unique code to each of 50 students?
Model answer
Six bits are needed, since 2⁶ = 64 codes is enough for 50 students. Five bits give only 32 codes, which is too few.

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Computational Thinking

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The check is 45 + 27 = 72.

denarybinaryhexadecimal

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AA normal test value is 14.

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A kibibyte (KiB) is 1,024 bytes. The figure 1,024 is 2¹⁰.

TrueFalse

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