1.2.1 | TEXT, SOUND AND IMAGES

Topics from the Cambridge IGCSE (9-1) Computer Science 0984 syllabus 2023 - 2025.

OBJECTIVES
1.2.1 Understand how and why a computer represents text and the use of character sets, including American standard code for information interchange (ASCII) and Unicode

ALSO IN THIS TOPIC
1.1.1 NUMBER SYSTEMS
1.1.2 NUMBER SYSTEMS
1.1.3 NUMBER SYSTEMS 
1.1.4 NUMBER SYSTEMS
 ​1.1.5 NUMBER SYSTEMS
1.1.6 NUMBER SYSTEMS
YOU ARE HERE | ​1.2.1 TEXT, SOUND AND IMAGES
1.2.2 TEXT, SOUND AND IMAGES
1.2.3 TEXT, SOUND AND IMAGES
1.3.1 STORAGE AND COMPRESSION
​1.3.2 STORAGE AND COMPRESSION
​1.3.3 STORAGE AND COMPRESSION
​1.3.4 STORAGE AND COMPRESSION
TOPIC 1 KEY TERMINOLOGY
TOPIC 1 ANSWERS
TOPIC 1 TEACHER RESOURCES (CIE)

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ASCII AND UNICODE

Computers represent text using character sets, which are sets of characters and symbols that are assigned a unique binary code that can be understood by the computer. The use of character sets is important because it enables computers to store and display text in a standardized way, regardless of the language or alphabet used.

One of the most widely used character sets is the American Standard Code for Information Interchange (ASCII), which was developed in the 1960s for use with early computers. ASCII uses 7 bits to represent a total of 128 characters, including letters, numbers, and symbols commonly used in the English language. ASCII is widely used in the US, and is also used as a base for other character sets in different parts of the world.

As computers became more advanced and widespread, it became clear that the 128 characters of ASCII were not sufficient to represent all the characters and symbols used in different languages and scripts around the world. In response to this, Unicode was developed in the 1990s as a universal character set that could represent all characters used in any language or script. Unicode uses 16 bits to represent a total of 65,536 characters, including characters from different scripts such as Latin, Arabic, Chinese, and many more.

Unicode has become the standard for representing text in modern computing, and most modern operating systems, applications, and programming languages support Unicode. The use of Unicode has enabled the development of software and applications that can display text in different languages and scripts, which has been important for global communication and accessibility.

In summary, computers represent text using character sets, which are sets of characters and symbols assigned unique binary codes. The American Standard Code for Information Interchange (ASCII) is a widely used character set that uses 7 bits to represent 128 characters, while Unicode is a universal character set that uses 16 bits to represent 65,536 characters, including characters from different scripts and languages.

1: What is a character set?
A) A set of fonts used by a particular software program
B) A set of colours used in graphic design
C) A set of characters and symbols assigned a unique binary code that can be understood by a computer
D) A set of keyboard shortcuts for commonly used commands

2: What is the American Standard Code for Information Interchange (ASCII)?
A) A set of computer hardware standards
B) A type of computer virus
C) A character set used for representing text
D) A programming language used for web development

3: Why was Unicode developed?
A) To provide a standardized way of representing text across different languages and scripts
B) To provide a more efficient way of compressing digital images
C) To provide a faster way of processing mathematical equations
D) To provide a more secure way of encrypting data

4: What is the difference between ASCII and Unicode?
A) ASCII is a universal character set, while Unicode is only used for representing English text
B) ASCII uses 8 bits to represent characters, while Unicode uses 16 bits
C) ASCII is a newer character set than Unicode
D) ASCII can only represent characters from the English language, while Unicode can represent characters from any language or script

5: Why is the use of character sets important in computing?
A) It enables computers to store and display text in a standardized way, regardless of the language or alphabet used
B) It makes it easier for programmers to write code
C) It helps to prevent computer viruses and malware
D) It allows computers to perform mathematical calculations more efficiently

ALSO IN THIS TOPIC

1.1.1 NUMBER SYSTEMS | Why Computers use Binary
1.1.2 NUMBER SYSTEMS | Binary, Hex and converting between number systems 
1.1.3 NUMBER SYSTEMS | Benefits of Hex
1.1.4 NUMBER SYSTEMS | Binary Addition and Overflow
1.1.5 NUMBER SYSTEMS | Binary Shifts
1.1.6 NUMBER SYSTEMS | Negative Number Representation, Two's Complement
1.2.1 TEXT, SOUND AND IMAGES | How Computers Represent Text
1.2.2 TEXT, SOUND AND IMAGES | How Computers Represent Sound
1.2.3 TEXT, SOUND AND IMAGES | How Computers Represent Images
1.3.1 STORAGE AND COMPRESSION | How Data Storage is Measured
​1.3.2 STORAGE AND COMPRESSION | Calculating Image and Sound File Size
​1.3.3 STORAGE AND COMPRESSION | Purpose of Data Compression
​1.3.4 STORAGE AND COMPRESSION | Lossy and Lossless, how files are compressed
TOPIC 1 KEY TERMINOLOGY
TOPIC 1 ANSWERS
TOPIC 1 TEACHER RESOURCES (CIE)