By
Mr. Abdalla A. Shaame
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What is Computer
 An electronic device that stores,
retrieves, and processes data, and can
be programmed with instructions.
 A computer is composed of hardware
and software, and can exist in a variety
of sizes and configurations.
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Computer System
 Computer system consist of four basic hardware
components: input, process, output and storage.
 The term hardware refers to the physical components
of your computer such as the sys tem unit, mouse,
keyboard, monitor etc.
 The software is the instructions that makes the
computer work.
 Software is held either in the computers hard disk,
CD-ROM, DVD or on a diskette (floppy disk) and is
loaded (i.e. copied) from the disk into the computers
RAM (Random Access Memory), as and when
required.
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Types of Computers
Mini and Mainframe Computers
 Very powerful, used by large organisations such an banks to
control the entire business operation. Very expensive!
Personal Computers
 Cheap and easy to use. Often used as stand-alone
computers or in a network.
 May be connected to large mainframe computers within
big companies.
 Personal computers come in a variety of forms such as
desktops, laptops and personal digital assistants (PDA)
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Hardware
Components
Input Devices -- "How to tell it what to do“
 - A keyboard and mouse are the standard way to
interact with the computer. Other devices include
joysticks and game pads used primarily for games.
Output Devices -- "How it shows you what it is
doing"
- The monitor (the screen) is how the computer sends
information back to you. A printer, speaker are
example of output devices.
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Hardware Components
Storage Devices -- "How it saves data and programs“
 - Hard disk drives are an internal, higher capacity drive
which also stores the operating system which runs
when you power on the computer.
 - "Floppy" disk drives allow you to save work on small
disks and take the data with you.
 Flush disk used as an alternative to floppy disk which
is used to store data. It vary in size up to 8GB
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Identify the following hardware
devices
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Characteristics of Hardware components
 Speed
 Capacity
 Cost
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Main parts of Computer
Memory -- "How the processor stores and uses
immediate data“
RAM - Random Access Memory
 The main 'working' memory used by the computer.
 When the operating system loads from disk when you
first switch on the computer, it is copied into RAM.
 computer will operate faster if you install more RAM.
 Data and programs stored in RAM are volatile (i.e. the
information is lost when you switch off the computer).
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Memory
ROM – Read Only Memory
 Read Only Memory (ROM) as the name suggests is a
special type of memory chip that holds software that
can be read but not written to.
 A good example is the ROM-BIOS chip, which
contains read only software.
 Often network cards and video cards also contain
ROM chips.
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How Computer Memory Is
Measured
Bit
 All computers work on a binary numbering system, i.e.
they process data in one's or zero's. This 1 or 0 level of
storage is called a bit.
Byte
 A byte consists of eight bits.
Kilobyte
 A kilobyte (KB) consists of 1024 bytes.
Megabyte
 A megabyte (MB) consists of 1024 kilobytes.
Gigabyte
 A gigabyte (GB) consists of 1024 megabytes.
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Microprocessors
"The brain of the computer“
 - PCs primarily use microprocessors (sometimes called the chip).
 The older Intel versions include the 386, 486 and now the
Pentium line.
 The CPU (Central Processing Unit) is normally an Intel Pentium
(or equivalent) and it is one of the most important components
within your computer.
 It determines how fast your computer will run and is measured
by its MHz speed.
 Thus a 600 MHz Pentium is much faster than say a 400 MHz
Pentium CPU.
 It is the CPU that performs all the calculations within the
computer.
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Factors that impact the performance of
Computer
 CPU speed
 RAM size
 Hard disk speed and capacity
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Software Components
 Software refers to any program that tells the computer
system what to do.
 Software are divided into:
 System Software
 Application Software
System Software: Are those software for system uses. Eg
Operating system, and utilities.
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Operating System
 Is a software which control all other parts of computer.
 The operating system is a special type of program that loads
automatically when you start your computer.
Objectives of Operating system
 To facilitates communication between the computer system and
its users.
 To facilitates communications among computer system
components
 To facilitates communication between linked computer system.
 To maximize throughput
 To optimize the use of computer system resources
 To keep track of all files in disk storage
 To provide an envelop of security for the computer system
 To monitor all system capabilities and alert the user of system
failure or potential problems
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Relationship between the Operating
System and Applications Software
 The operating system coordinates all
software activity within a computer
system.
 The interaction of user to Operating
system is through the Graphical User
Interface (GUI)
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PC Platforms
The most common types of
operating system are:
Microsoft windows
Mac OS
UNIX/Linux
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Window Platforms
Early versions of Windows
 Windows 95, Windows 98, Windows ME are old
versions of Windows but still can be used in the home
and in business.
 These old versions of Windows are emerged from MSDOS, a text based operating system.
 Windows NT was the first operating system to divorce
itself from the limitations of MS-DOS
 Windows 2000 was the successor to Windows NT.
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Windows Platform
Modern PC Operating system
 Window XP and its successor (ie Windows Vista and
Windows 7) is a foundation for Windows family of client
operating systems. These Operating System works with
Windows 2003 Server, the server side portion of the
operating system (which runs on the server computer) to
make client/server computing possible.
 Windows XP, Windows Vista and Windows 7 comes in
several versions for home, office and taplet PCs.
 Popular features of modern OS are plug-and-play and
home networking
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Windows Platform
Windows CE. NET
 The Windows CE. NET operating
system designed for hand-held, pocket
PCs, and other small-footprint devices
 Windows CE. NET users can share
information with other Window based
PCs and they can connect to the
internet.
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The Macintosh/Mac OS X Platform
 The Apple family of microcomputers
(including the Power Mac G4, iMac,
eMac Desktop and iBook notebook)
and its operating system, Mac OS X
 The Apple line of microcomputers is
based on the Motorola family of
microprocessors.
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UNIX/ Linux
 Created in the 1970s, Unix was the one operating
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system with the flexibility to be used on almost any
computer.
UNIX is a multiuser operating system, become very
popular in Universities and mostly used for powerful
workstation.
However the UNIX movement has been slow until
recently.
Linux is a free and open source software where its
source code available free, free to use, to copy and
distribute to others.
Currently, the Linux is become competitors to
Windows system for client and server.
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UTILITY PROGRAMS
 A wide variety of system software utility is
available to help you with the day-to-day
tasks associated with personal computing.
 It include disk and file maintenance, system
recovery, security, backup, virus protection,
and so on.
 The purpose of utility is to keep the system
running at peak performance.
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Application Software
 Application software are those software designed
for users.
 An application program is the type of program that
you use once the operating system has been
loaded.
 Application software divided into:
 General purpose software: Those software for
general uses. Eg, Ms word, Ms Excel, Ms Power
point, etc
 Special purpose software: Those software for
special uses. Such as QuickBooks for accounting,
Banking software, etc
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Discussion
 Why is the selection of a platform such
an important decision to an
organization.
 Discus consequence of not performing
routine disk maintenance with utility
software.
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Next Lesson
Computer impact and applications
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