Download Cambridge IGCSE Computer Science Book PDF

TitleCambridge IGCSE Computer Science Book
File Size13.8 MB
Total Pages278
Table of Contents
                            Title Page
Acknowledgements
Copyright
Contents
Introduction
Section 1 Theory of computer science
	Chapter 1 Binary systems and hexadecimal
		1.1 Introduction
		1.2 The binary system
		1.3 Measurement of the size of computer memories
		1.4 Example use of binary
		1.5 The hexadecimal system
		1.6 Use of the hexadecimal system
	Chapter 2 Communication and internet technologies
		2.1 Introduction
		2.2 Data transmission
		2.3 Error-checking methods
		2.4 Internet technologies
	Chapter 3 Logic gates and logic circuits
		3.1 Introduction
		3.2 Logic gates
		3.3 Truth tables
		3.4 The function of the six logic gates
		3.5 Logic circuits
		3.6 Logic circuits in the real world
	Chapter 4 Operating systems and computer architecture
		4.1 Introduction
		4.2 Operating systems
		4.3 Interrupts
		4.4 Computer architecture
		4.5 The fetch–execute cycle
	Chapter 5 Input and output devices
		5.1 Introduction
		5.2 Input devices
		5.3 Output devices
	Chapter 6 Memory and data storage
		6.1 Introduction
		6.2 File formats
		6.3 Lossless and lossy file compression
		6.4 Memory and storage
		6.5 How to estimate the size of a file
	Chapter 7 High- and low-level languages
		7.1 Programming languages
		7.2 Translators
		7.3 What happens when things go wrong?
	Chapter 8 Security and ethics
		8.1 Introduction
		8.2 Security and data integrity
		8.3 Cookies
		8.4 Loss of data and data corruption
		8.5 Firewalls and proxy servers
		8.6 Security protocols
		8.7 Encryption
		8.8 Applications
		8.9 Computer ethics
		8.10 Free software, freeware and shareware
Section 2 Practical problem-solving and programming
	Chapter 9 Problem-solving and design
		9.1 Introduction
		9.2 Algorithms
		9.3 Test data
		9.4 Validation and verification
		9.5 Using trace tables
		9.6 Identifying and correcting errors
		9.7 Producing algorithms
	Chapter 10 Pseudocode and flowcharts
		10.1 Introduction
		10.2 Assignment
		10.3 Conditional statements
		10.4 Loop structures
		10.5 Input and output statements
		10.6 Standard actions
		10.7 Examples of algorithms in pseudocode
		10.8 Standard flowchart symbols
	Chapter 11 Programming concepts
		11.1 Introduction
		11.2 Programming
		11.3 Declaration and use of variables and constants
		11.4 Basic data types
		11.5 How to make your program work
	Chapter 12 Data structures: arrays and using pre-release material
		12.1 Introduction
		12.2 Arrays
		12.3 Using pre-release material
	Chapter 13 Databases
		13.1 Introduction
		13.2 What are databases used for?
		13.3 The structure of a database
		13.4 Practical use of a database
Index
                        
Document Text Contents
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7 High- and low-level languages
In this chapter you will learn about:
• programming languages
• high-level languages
• low-level languages
• translators
• compilers
• interpreters
• assemblers.

7.1 Introduction
People use many different languages to communicate with each other. In order for
two people to understand each other they need to speak the same language or another
person, an interpreter, is needed to translate from one language to the other language.
Programmers use many different programming languages to communicate with
computers. Computers only ‘understand’ their own machine code. A program needs
to be translated into machine code before it can be ‘understood’ by a computer.

7.2 Programming languages

7.2.1 What is a program?
Programs are our way of telling a computer what to do, how to do it and when to do
it. This enables a single computer to perform many different types of task. A
computer can be used to stream videos, write reports, provide weather forecasts and
many, many other jobs.

An example of a simple task that can be performed by a computer is the provision
of a multiplication tables test. Figure 7.1 shows a simple program to set this up and
Figure 7.2 shows an example of the test in use.

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Figure 7.1 Program written in Scratch

Figure 7.2 Program in use

Activity 7.1
Find at least ten different tasks that computer programs perform in your
school.

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terabyte (TB) 4
terminator symbols 142
test data 119–120, 140, 169
text, ASCII format 80
text files

file compression 80
formats 52, 80
size 88

TIFF, raw bitmap image 78
timeout 21
tomography 53–54
top-down design 114, 115–116
totalling 154–155, 159
touch pad, on laptop computers 58
touchscreen technology 51, 58, 61
trace tables 125–127
trackerball 58–59
translator programs 92–94
transport layer security (TLS) 103–104
truth tables 26–29

for logic circuits 29–38
TVs, ‘smart’ 86
type checks 121

U
UAA (universally administered MAC address) 11
uniform resource locator see URL
universal serial bus see USB
UNIX 42
URL (uniform resource locator)

hexadecimal 13
IP address 23
parts 25
stored in QR code 57

USB (universal serial bus)
data transmission method 15, 16, 57, 58, 59, 88
flash memories 81, 84, 87

user id/name 22, 98, 101, 107

V
validation

of input 166

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methods 120–124
in Microsoft Access 173
types of checks 121

variable
as an index in an array 165
in a computer program 149

velocity byte, in MIDI files 76
verification 124
VIN (vehicle identification number), check digit 122
viruses 98
Visual Basic 146
voice recognition 59–60, 108
von Neumann architecture 45–46

W
wardriving 100
web address see URL
web browser see browser
WEP (wired equivalent privacy) encryption 100
WHILE … DO … ENDWHILE loop structure 137, 138
Windows 42–43
wireless, password protection 100
WRITE operation 47

X
XOR gate 26, 29

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