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

Why do computers work in binary rather than in denary?

An electronic circuit can distinguish two states such as on and off reliably even when voltages drift, whereas telling ten separate voltage levels apart would be slow and error-prone.

A byte is a group of eight bits, and it is the smallest block that is normally given its own address in memory.

What is a nibble, and why is it a convenient grouping?

A nibble is four bits, half a byte, and it is convenient because one nibble corresponds to exactly one hexadecimal digit.

What is meant by the word length of a processor?

The word length is the number of bits the processor handles as a single unit, which is the width of its registers and of the data it moves and operates on in one go.

What word lengths are usual in general purpose processors today?

Thirty-two bits and sixty-four bits are the usual sizes, with sixty-four bits now standard in desktop and mobile machines.

WJEC A-Level Computer Science 601-5345-3

Hardware: Architecture, Memory and Storage

Topic overview Components of a computer system and how they connect Von Neumann architecture and the CPU The fetch-execute cycle Memory and caching Parallel processing Input and output devices and their uses Secondary storage, fragmentation and defragmentation

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Logic Gates and Boolean Algebra

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Data Representation and Data Types

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Data Structures

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Database Systems

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Data Security and Integrity

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Computing, Society and the Law

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Databases and Distributed Systems

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Data Security, Cryptography and Attack

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Data Representation and Data Types

Bits, bytes and words

3 things to know
AS Unit 1

Overview

Word length of a processor and kilobyte and a kibibyte.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why does a longer word length give better performance?

Numbers

Distinguish between a kilobyte and a kibibyte.

Key term

What is a bit?

Questions from this subtopic

Each one with the model answer underneath.

1
What is a bit?
Model answer
A bit is the smallest unit of data a computer holds, a single binary digit that is either 0 or 1.
2
Why do computers work in binary rather than in denary?
Model answer
An electronic circuit can distinguish two states such as on and off reliably even when voltages drift, whereas telling ten separate voltage levels apart would be slow and error-prone.
3
What is a byte?
Model answer
A byte is a group of eight bits, and it is the smallest block that is normally given its own address in memory.
4
What is a nibble, and why is it a convenient grouping?
Model answer
A nibble is four bits, half a byte, and it is convenient because one nibble corresponds to exactly one hexadecimal digit.
5
What is meant by the word length of a processor?
Model answer
The word length is the number of bits the processor handles as a single unit, which is the width of its registers and of the data it moves and operates on in one go.
6
What word lengths are usual in general purpose processors today?
Model answer
Thirty-two bits and sixty-four bits are the usual sizes, with sixty-four bits now standard in desktop and mobile machines.

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A bit is a single binary digit.

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Bits, bytes and words

Overview

What you need to know

Why does a longer word length give better performance?

Distinguish between a kilobyte and a kibibyte.

What is a bit?

Questions from this subtopic

What is a bit?

Why do computers work in binary rather than in denary?

What is a byte?

What is a nibble, and why is it a convenient grouping?

What is meant by the word length of a processor?

What word lengths are usual in general purpose processors today?

Other ways to work this

What is inside Levo

The 3-step method, run for you

Cram a whole paper in one sitting

Blank Blitz makes facts automatic

Build It gets the exam shape right

Test It catches misconceptions

Brain Breaks between sessions

Every question in Data Representation and Data Types, on a schedule.