I.C.T.
Ch.1: Computer System
Chapter 1
Computer System
Eng. Mustafa El-Komy
Eng. Omar El Safty
1
Theory Notes
I.C.T.
Ch.1: Computer System
A computer is a device that receives input, does processing on that input and then
produces the output. Computer consists of two main components: hardware and
software.
Input Processing Output 1.1 Hardware and Software
Hardware It is a general term for the physical components that make up a computer system.
Hardware can be either External or Internal.
External Computer Hardware External hardware devices are the ones that are
external and can be seen by the user. For
example: mouse, keyboard, monitor, printer,
scanner, etc. Essentially, input devices, output
devices and external storage devices are
external hardware.
Internal Computer Hardware Internal hardware devices are the devices that are internal inside the computer itself
and are not normally visible by the user.
Examples of internal hardware are:
• Motherboard
o It allows the processor and other
computer hardware to function and
communicate with each other. It acts
as a kind of hub that other computer
devices connect to.
• Random Access Memory (RAM)
• Read-Only-Memory (ROM)
• Video Card
o Allows the computer to send graphical information to a video display
device such as a monitor, television or projector.
o Usually connects to motherboard.
Eng. Mustafa El-Komy
Eng. Omar El Safty
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Theory Notes
I.C.T.
Ch.1: Computer System
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Sound Card
o Provides the computer with the ability to produce sounds, which can be
heard by the user through speakers or headphones.
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Internal hard disk drive/solid state drive (HDD/SDD)
o Hard disk drives (HDD) are magnetic in nature and are one of the main
methods of storing data, files and most of the application and system
software.
o More modern computers use newer storage systems that make use of
solid state drive (SSD) technology and are replacing HDD in many
cases. Their function is the same as HDD.
Software It is a general term for programs that control the computer system. There are two
types of software: Application and System.
Application Software They are programs that allow the user to do specific tasks.
Examples of application software are:
• Word processor
o This software is used to manipulate text documents. Text
is entered using a keyboard and the software provides
tools for copying, deleting and various types of
formatting.
o Other of the functions include:
§ Creating, editing, saving and manipulating text.
§ Copy and past functions.
§ Spell checking.
§ Importing images.
§ Translation into other languages.
• Spreadsheet (Excel)
o It is used to organize and manipulate numerical data.
o Numbers are organized on a grid of lettered columns and
numbered rows. The grid itself is made of cells.
o Some of the functions include:
§ Use of formulas to carry out calculations
§ Ability to produce graphs
§ Ability to do modeling and ‘what if’ calculations.
Eng. Mustafa El-Komy
Eng. Omar El Safty
3
Theory Notes
I.C.T.
Ch.1: Computer System
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Database
o It is used to organize, manipulate and analyze data.
o Some functions of database include:
§ Ability to carry out queries on database data and produce a
report.
§ Add, delete and modify data in a table.
Control and measuring software
o It is designed to allow a computer or microprocessor to interface with
sensors so that it is possible to:
§ Measure physical quantities in the real world (such as
temperature).
§ Control applications by comparing sensor data with stored data
and sending out signals to control devices to do some action.
Apps/ Applets
o Normally refers to the type of software that runs on mobile phones or
tablets.
o They are usually downloaded from and ‘App Store’ and range from
games to sophisticated software such as phone banking.
o Example of apps:
§ Video and music streaming.
§ GPS.
§ Camera facilities.
Photo editing software
o It allows a user to manipulate images stored on a
computer.
o Examples of such manipulations are:
§ Changing brightness.
§ Changing contrast.
§ Altering color saturation.
§ Removing ‘red eye’.
Video editing software
o It allows a user to manipulate videos to produce and edited video.
o It enables the addition of titles, colour correction, altering/adding sound
to the original video and other things.
Graphics manipulation software
o It allows for manipulation of lines, curves and text in order to alter an
image as required.
Eng. Mustafa El-Komy
Eng. Omar El Safty
4
Theory Notes
I.C.T.
Ch.1: Computer System
System Software They are programs that allow the hardware to run properly and allow the user to
communicate with the computer.
Examples of system software are:
• Compiler
o It is a computer program hat translates a program written in a high level
programing language into machine code (code understood by the
computer) so that it can be interpreted by the computer to do specific
task.
o Examples of high-level languages include: C++, Java and Python.
• Linker
o It is a computer program that takes one or more files produced by a
compiler and combines them into a single program that can be run on a
computer.
o Many programming languages allow programmers to separate their
code and write them in different modules. This simplifies the
programming task since it allows the program to be broken up into
small sub tasks. However, at some point, it will be necessary to put all
the modules together to form the final program. This is the linker’s job.
• Device driver
o It the name given to software that enables one or more hardware
devices to communication with the computer’s operating system.
o Without drivers, a hardware device (for example, a printer) would be
unable to work with the computer.
o All hardware devices connected to a computer have associated drivers.
As soon as a device is plugged into the USB port of a computer, the
operating system looks for the appropriate driver.
• Operating System (OS)
o It is software running in the background of a
computer system and manages many of the
basic functions.
o Without the OS, most computers would be very
user-unfriendly and the majority of the users
would find it almost impossible to work with
computers.
o Examples: Windows, Linux, Android, etc.
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Utilities
o Utility programs are programs that help to manage, maintain and
control computer resources.
Eng. Mustafa El-Komy
Eng. Omar El Safty
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Theory Notes
I.C.T.
Ch.1: Computer System
o Examples of utility programs include:
§ Antivirus.
§ Anti-spyware.
§ Backup of files.
§ Disk repair.
§ File management.
§ Security.
§ Screensavers.
1.2 Computer main components
Main / Internal Memory Central Processing Unit (CPU) Input Devices Output Devices Secondary /Backing storage Central Processing Unit (CPU) The CPU is the part o the computer that interprets and executes the commands from
the computer hardware and software. It is normally part of the computer
motherboard. It controls all parts of the computer and tells the computer how to
perform a specific task. As a result, the CPU is considered the 'brain' of the
computer.
Main/Internal memory Any data or instructions that are to be processed by the CPU must be placed into
main memory (sometimes known as primary storage). It is made of RAM and ROM.
Random Access Memory (RAM) Random Access Memory (RAM) is the part of the computer that
temporarily stores the instructions that the computer is running,
and the data it is processing.
RAM is a volatile storage device. This means that if the
computer's power is turned off the contents of RAM disappear
and are lost.
When a computer is running, its RAM will contain:
• The operating system software
Eng. Mustafa El-Komy
Eng. Omar El Safty
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Theory Notes
I.C.T.
Ch.1: Computer System
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The application software currently being used
Any data that is being processed
Read-­‐Only Memory (ROM) Read-Only Memory (ROM) is a memory used to store information that needs to be
permanent. It is used to contain, for example, configuration data for a computer
system. It also holds a special piece of software called ‘BIOS’, which is responsible
for locating and loading the operating system.
ROM is non-volatile storage. This means that the data it contains is never lost, even
if the power is switched off.
Input devices These are devices that are used to input data into the computer. A keyboard, a
mouse and a webcam are all examples of input devices.
Output devices These are devices that are used to obtain output from the computer.
A monitor, a printer and a loudspeaker are all examples of output devices.
Secondary/backing storage These are devices that store data when the computer is switched off. Secondary
storage is non-volatile, so data that is stored on these devices remains there safely.
A hard drive, a CD-ROM, a floppy disc and a USB memory stick are all examples of
secondary storage devices.
1.3 Operating systems
An operating system is a special piece of software that manages the general
operations of a computer system:
ü It provides a user interface so that the user can
interact with the computer
ü It manages applications that are running on the
computer, starting them when the user
requests, and stopping them when they are no
longer needed
ü It manages files, helping the user save their
work, organize their files, find files and load files
ü It manages the computer memory, deciding what should be loaded into
memory and what should be removed
Eng. Mustafa El-Komy
Eng. Omar El Safty
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Theory Notes
I.C.T.
Ch.1: Computer System
ü It manages computer security, preventing unauthorized access to the system
ü It manages the computer's input and output hardware such as printers, etc.
User Interface There are two types of user interfaces:
• Graphical User Interface (GUI)
• Command-Line Interface (CLI)
Graphic User Interface (GUI) A GUI is an interface built around visual
(graphical) things:
§ Windows are regions of the screen used to
display information
§ Icons are small pictures that are used to
represent folders, software, etc.
§ Menus are lists of options the user can select from
§ A pointer is an arrow that can be moved around the screen and is used to
select things
Windows XP is an example of an operating system with a GUI.
GUIs are quite easy to use due to the visual nature of the interface - the user has lots
of visual clues as to what things do.
However, to display all of the nice graphics required by a GUI takes a lot of
computing power so quite a powerful computer is needed.
GUI is intended for the end-user who doesn’t have (or doesn’t need) any great
knowledge of how the computer works.
Advantages of using GUI
• The user doesn’t have to learn any commands.
• Easier to change/edit actions.
• It is more user-friendly (for example: icons are used to represent applications).
• A pointing device (such as a mouse) is used to click on an icon to launch an
application, which is simpler than typing in commands.
Disadvantages of using GUI
• It uses up considerably more computer memory than CLI.
• The user is limited to the icons provided on the screen.
• It needs an operating system, such as Windows, to operate, which uses up
considerable memory.
Eng. Mustafa El-Komy
Eng. Omar El Safty
8
Theory Notes
I.C.T.
Ch.1: Computer System
Command Line Interface (CLI) The user would have to learn all the
commands to make use of the computer
system.
This kind of interface is quite difficult to use,
so it is only suitable for expert users.
Advantages of using CLI
• The user is in direct communication with the computer.
• The user is not restricted to a number of predetermined options.
• It is possible to alter computer configuration settings.
Disadvantages of using CLI
• The user needs to learn a number of commands, to carry out basic
operations.
• All commands need to be typed in, which takes time and can be error-prone.
• Each command must be typed in using the correct format, spelling, and so on.
• It is more difficult to edit once commands are entered.
1.4 Types of computer
1. PC/Desktop computers PC/Desktop usually refers to a general-purpose computer
that is made up of a separate monitor, keyboard and
processor unit.
Advantages of desktop computers over laptop computers
• Spare parts and connections tend to be standardized, which usually results in
lower costs.
• Power consumption is not critical since they usually plug straight into a wall
socket.
• Because they are usually fixed in one location, there is less chance for them
to be damaged.
• Internet access is also more stable since they are not moved around (the user
will always have the same data transfer rate).
Eng. Mustafa El-Komy
Eng. Omar El Safty
9
Theory Notes
I.C.T.
Ch.1: Computer System
Disadvantages of desktop computers compared to laptop computers
• Not portable.
• Because it is not portable, it is necessary to copy files when you want to do
work elsewhere – with a laptop you simply take the whole computer with you.
• Tend to be more complicated since all the components need to be carried
around with you and then connected to the computer by wires or wireless
connections, which also consumes space.
2. Laptop computers Laptop refers to a type of computer where the monitor,
keyboard, touchpad and processor are all together in one
single unit. This makes them extremely portable.
Key features in a laptop
• Lightweight (to aid portability).
• Low power consumption.
• Processor shouldn’t generate too much heat (cooling is important for the
laptop to survive).
Advantages of laptop computers over desktop computers
• Portability.
• No trailing wires as everything is in one single unit.
• They can take full advantage of Wi-Fi.
• They can link into any multimedia system.
Disadvantages of laptop computers compared to desktop computers
• As they are easily portable, they are also easier to steal.
• They have limited battery life, so the user may need to carry a heavy adaptor.
• Keyboards and touchpad can sometimes be hard to use.
3. Smartphones Smartphones allow normal phone calls to be made
but also have an operating system (such as iOS,
Android or Windows), allowing them to run a number
of computer applications.
They allow users to send/receive emails and
messages, use a number of Apps, use camera feature, MP3 and MP4 players (for
music and videos), and so on.
Smartphones communicate with the Internet either by using Wi-Fi hotspots or by
using 3G/4G/5G mobile phone networks.
Eng. Mustafa El-Komy
Eng. Omar El Safty
10
Theory Notes
I.C.T.
Ch.1: Computer System
Advantages of smartphones
• They are very small in size and lightweight – therefore very easy to carry (this
is more difficult with laptops as they are much bulkier and heavier).
• Can make phone calls as well as connect to the Internet while on the move.
• Because they can use Wi-Fi and mobile phone networks, they can be used
almost anywhere (this is not the case with laptops or PCs).
• They have hundreds of Apps (similar to tablets, but it is an advantage
compared to laptops)
• They have a reasonable battery life compared to laptops.
Disadvantages of smartphones
• The small screens make page difficult to read and small keyboards make
typing things in more difficult and slower (laptops and PCs have much bigger
screens and keyboards).
• Web browsing and photography can drain the battery quickly.
• Memory size in most phones isn’t very large when compared to laptops and
PCs – although it is comparable with tablets.
• Not all website features are compatible with smartphone operating systems.
• Because of their small size, it is much easier to lose a smartphone than
laptops or PCs.
4. Tablets Tablets are relatively new internet-enabled portable
computer. They work in a similar way to a smartphone.
Tablets use touch screen technology and don’t usually
have a conventional keyboard. Internet access is usually
through Wi-Fi or through 3G/4G/5G (mobile phone)
connectivity.
Key features in tablets
• High-definition, anti-glare displays.
• Front-facing and back-facing cameras.
• Lower weight and longer battery life than laptops.
• Bluetooth connection to printers and other devices.
• Flash memory cards and cloud storage facilities to back up and sync data
sources.
• Can include speech-recognition systems (such as Siri) to enable verbal
instructions to be understood by the tablet.
Eng. Mustafa El-Komy
Eng. Omar El Safty
11
Theory Notes
I.C.T.
Ch.1: Computer System
Advantages of tablets over laptop computers
• Very fast to switch on (no time delay waiting for the operating system to load
up).
• Fully portable.
• Touch screen technology means they are simple to use and doesn’t need any
other input devices.
• Can use several Apps.
• Don’t generate any heat as they use solid-state technology.
• Battery life of a tablet is a lot longer.
• When the power button is pressed it goes into standby but remains connected
to the internet, so the user still hears alerts when emails of other notifications
are received.
Disadvantages of tablets compared to laptop computers
• They often have limited memory or storage compared to a laptop.
• They can be expensive to run if the internet is being accessed frequently via
3G/4G/5G mobile phone networks.
• Typing on a touch screen can be slow and error-prone compared to a
standard keyboard.
• Transferring of files often has to be done through an ‘App Store’.
• Laptops tend to support more types of file format than tablets, and are also
better equipped to run different types of software.
Eng. Mustafa El-Komy
Eng. Omar El Safty
12
Theory Notes