302_System_Software_082747 by Abraham.ppt

System Software
COMPUTER STUDIES DEPARTMENT
1

System Software
 System software is a set of programs that control or
maintain all the operations of the computer and its
devices, such as the CPU, communication links, and
peripheral devices.
 System software serves as the interface between the
user, the application software, and the computer's
hardware.
 System Software Includes:
 An Operating system and Device Drivers
 Utility Programs and
 Programming Languages (Translators and Library Programs)
2

Operating Systems
 An operating system is a generalized program
that manages and coordinates all the activities
taking place within a computer system.
 The operating system functions as a
middleman between the user and the computer,
as well as between application software
programs and the hardware devices.
7/29/2024 3

Device Drivers
 To communicate with the hardware devices, the
operating system relies on device drivers.
 A device driver is a program that accepts
instructions and then converts them into
commands that the device understands.
 Each device on a computer, such as the
keyboard, mouse, monitor, printer, card
reader/writer, and scanner, has its own device
driver.
4

5
How the operating system
acts as a middleman
between the user, the
input, processor and the
output devices

Where does the OS reside?
 In most cases, the operating system is installed
and resides on the computer's hard disk.
 During the boot process, usually the operating
system will look first in drive C: (the
designation for the hard disk drive) for the OS
system files.
 On handheld computers and many mobile
devices such as smart phones, however, the
operating system may reside on a ROM chip.
6

The Kernel of the OS
 This refers to the core of an operating system,
responsible for managing memory, files, and
devices; maintaining the computer's clock;
starting applications; and assigning the
computer's resources.
 Each time you turn on the computer, the kernel
and other frequently used instructions in the
operating system are copied from the hard disk
to the computer's RAM
7

The term ‘Software Platform’
 The operating system that a computer uses
sometimes is called its software platform.
 When you purchase application software, the
package identifies the software platform on which it
runs.
 A cross-platform application is one that runs on
multiple operating systems.
 Often, these cross-platform applications contain
multiple versions, each corresponding to a different
operating system.
8

Functions of an Operating
System
Most operating systems provide
similar functions that are
outlined as follows :
a) Starting a computer,
(Booting the computer)
b) Providing a user interface,
c) Managing programs,
d) Configuring devices, (Device
drivers are often needed).
Plug and Play devices are
recognized automatically.
e) Monitoring performance
f) Providing file
management.
g) Administering security.
h) Managing resources.
i) Coordinating tasks, and
Spooling.
j) Managing memory,
k) Establishing an Internet
connection
9

Functions of an Operating System
7/29/2024 10

a) Starting a computer,
(Booting the computer)
 The process of starting or restarting a computer is
called booting.
 The process of turning on a computer after it had
been powered off completely is known as cold
booting.
 Warm booting is the process of restarting a computer
that already is powered on.
 When you install new software, often an on-screen
prompt instructs you to restart the computer. In this
case, a warm boot is appropriate.
7/29/2024 11

the Boot Process (cont…)
 On start up, the OS may verify that the person
attempting to use the computer is a legitimate
user through use of a password.
 After the user logs on, the desktop and icons
are displayed on the screen.
 Finally, the operating system also executes
programs in the Startup folder, which contains
a list of programs that open automatically when
you boot the computer.
12

Turning off the
Computer
 When you instruct
the computer to Turn
Off, (See figure), the
operating system
properly closes any
open processes and
programs, saves your
settings, and shuts
down the computer.
13

b) Providing a User Interface
 Computer users interact with software through
its user interface.
 A user interface is the part of the software with
which you interact; it controls how data and
instructions are entered and information is
presented on the screen.
 It is through the user interface of an operating
system that you communicate with the
computer.
14

Types of user interfaces
 Three types of user interfaces are:
i. command-line interface (CLI),
ii. menu-driven interface (MDI), and
iii. graphical user interface (GUI).
 Most operating systems use a combination of
these types of user interfaces to define how
you interact with your computer.
15

Command-line interface
- With a command-line interface, you type
keywords such as COPY , RENAME or DEL,
using the keyboard to enter instructions.
- A keyword is a special word, phrase, or code
that a program understands as an instruction.
- When working with a command-line interface,
the set of commands you use to interact with
the computer is called the command
language.
July 24

 Command-line interfaces often are difficult to
use because they require exact spelling,
grammar, and punctuation.
 Minor errors, such as a missing period,
generate error messages.
 Command-line interfaces, however, give a user
more control to manage detailed settings, and
execute programs faster.

(cont)
 Shown here are some typical CLI commands.
 NB To view a list of more common commands, type help at
the command prompt.
19

Menu-driven interface
 A menu-driven interface provides menus
as a means of entering commands.
 Menu-driven interfaces are easier to learn
than CLI because users do not have to
cram keywords for commands.
 The characteristic of being easy to learn
and use is described as being user-
friendly.

Graphical User Interface
(GUI)
 Most of today's software programs have a
graphical user interface (GUI).
 A GUI is a user Interface in which visual images
such as icons and buttons are used to issue
commands.
 Of all the interfaces a GUI typically is the most
user friendly, because it does not require you
to know any command language.
22

23
graphical user
interface (GUI)

Disadvantages of a
GUI as compared to CLI
 GUI requires the computer to have
more RAM as compared to Command
Line.
 Command line instructions execute
faster than GUI instructions.
7/29/2024 24

Examples of
Elements/
Objects of a
GUI
7/29/2024 25

Examples of Elements/
Objects of a GUI
 Icons
 Command Buttons
 Drop Down Lists
 Check boxes
 List Boxes
 Dialogue boxes
 Windows
 Cursor
 Scroll bars
 Radio Buttons
 Preview areas
 Slider buttons
 Tabs
 Menus
 Text boxes
 Toolbars
 e.t.c.

Examples of Elements/
Objects of a GUI
 A GUI menu displays a set of available
commands or options from which you choose
one or more.
 An icon is a small image that represents an
item such as a program, an Instruction, or a file.
7/29/2024 27

c) File management
 The operating systems help to organize files
and folders on a computer’s hard disk drive.

What is the difference
between a file and a folder?
 A file is a collection of bits that have been
processed and stored in secondary memory.
 A file may be a document that may contain
characters such a letter, a database, a
computer program, a song, a picture, etc.
 A folder is a directory that usually contains
related information. A folder can contain both
files and other sub folders.
 Folders are represented by a folder icon.
29

FILES
 The
operating
system also
assigns a
special
graphic
known as an
icon to each
file type.
30

File extension
 Each file type is
differentiated by its
unique file extension.
 A file extension is a
suffix to the name of a
file applied to indicate
the file format.
 It is separated from the
base filename by a dot.
31
COMMON FILE
EXTENSIONS

d) Managing Programs
 Operating systems can support just one user
running one program or many of users running
multiple programs.
 These various capabilities of operating systems
are described as
 (i) single tasking,
 (ii)Single-user and multi-user,
 (iii) multitasking, and
 (iv)multiprocessing,
32

(cont)
 A single user-single tasking operating system allows only
one user to run one program at a time, While
 A single user-multitasking operating system allows one user
to work on two or more programs that reside in memory at
the same time.
 A multi-user operating system enables two or more users to
run programs simultaneously. For example, mainframes,
allow hundreds of users to connect at the same time.
 A multiprocessing OS manages coordinated processing of
data by more than one processor. Multiprocessing increases
a computer's speed and helps in fault tolerant systems.
33

(cont)
 When a computer is running multiple programs
concurrently, one program is in the foreground
and the others are in the background.
 To make a program active, click on its tab on
the taskbar or its window.
 This causes the operating system to place it in
the foreground.
34

35
d) Managing
Programs
(cont)

(cont)
 In addition to application
programs, an operating
system manages other
processes.
 Some of these processes
are memory resident.
 They include utilities and
routines that provide
support to other
programs or hardware.
 . 36

e) Managing Memory
 The purpose of memory management is to optimize
the use of RAM. RAM holds data and instructions
while the processor is using them.
 The operating system allocates, data and instructions
to an area of memory while they are being processed,
and carefully monitors the contents of RAM.
 Finally, the operating system releases these items
from RAM when the processor no longer requires
them.
37

e) Managing Memory (cont.)
 If you have many programs running at a go, it is possible to
run out of RAM. So, the OS may have to use virtual memory.
 With virtual memory, the operating system allocates a
portion of a storage medium, usually the hard disk, to
function as additional RAM.
 As you interact with a program, part of it may be in physical
RAM, while the rest of the program is on the hard disk as
virtual memory.
 Users may notice the computer slowing down while it uses
virtual memory, because virtual memory is slower than RAM.
 The area of the hard disk used for virtual memory is called a
swap file
38

f) Coordinating Tasks
 The operating system determines the order in which
tasks are processed.
 A task, or job, is a piece of work or operation that the
processor manages.
 Tasks include receiving data from an input device,
processing instructions, sending information to an
output device, and transferring items from storage to
memory and from memory to storage.
 Thousands of tasks can be going on in a computer
simultaneously.
39

f) Coordinating Tasks (cont.)
 Sometimes, a device may be busy processing
one job when it receives a second job.
 This occurs because the processor operates at
a much faster rate of speed than peripheral
devices.
 For example, if the processor sends five print
jobs to a printer, yet the printer can print only
one document at a time.
40

 When this happens, the OS allocates / assigns
memory to the jobs in the execution queue in an area
called the buffer.
41

 A BUFFER is an area of memory or storage in which data and
information is placed while waiting to be transferred to or from an
input or output device.
 Operating systems typically use a technique called spooling to
increase computer system efficiency.
 SPOOLING refers to the process of putting tasks that need to be
done into a buffer until they can be executed.
 The operating system commonly uses a print spooler with print
jobs. A print spooler, intercepts documents to be printed from the
operating system and places them in the queue in the buffer.
 As soon as the print job is placed in the buffer, the CPU is
available to process the next instruction.
42

Spooling (illustration)
 Spooling increases both processor and printer
efficiency by placing print jobs in a buffer on disk
before they are printed.
43

g) Configuring Devices
 If you add a new device to your computer, such
as a printer, its driver must be installed before
the device will be operational.
 For devices with Plug and Play support, the OS
recognizes the new device and loads the
necessary drivers automatically.
 It also checks for conflicts with other devices.
44

g) Configuring Devices
(cont)
 For devices that are not Plug and Play, Windows
operating system provides a wizard to guide users
through the installation steps.
 If you have an Internet connection, the Wizard will
search an online repository of device drivers.
 If Windows still is unable to find a driver, you can
download one from the manufacturer's Web site
manually.
 Alternatively you can install the drivers from a
CD-ROM provided with the purchased device.
45

h) Establishing an Internet
Connection
 Operating systems typically provide a means to
establish Internet connections.
 This is through a "Connect to a network" Wizard that
guides users through the process of setting up a
connection between a computer and an Internet
service provider.
 Some operating systems also include a Web browser
and an e-mail program, enabling you to begin using
the Web and communicate with others as soon as
you set up the Internet connection.
46

i) Monitoring Performance
 The OS monitors the performance of the computer system.
 It keeps track of each computer job, the various system
resources and devices, the processor usage, the amount of
unused physical RAM, and network usage.
 Operating systems typically contain a performance monitor.
 A performance monitor is a program that assesses and
reports information about various computer resources and
devices.
 The information in performance reports helps users and
administrators to identify a problem with the resources so
they can try to resolve any problems.
47

j) Administering Security
 The OS helps users to administer computer access
security by use of a user name or user ID and a
password, before a user logs on to, a computer.
 After entering a user ID and password, the operating
system compares the user's entry with a list of
authorized user names and passwords.
 If the entry matches the user name and password
kept on file, the operating system grants the user
access.
48

j)Administering Security
(cont)
 To protect sensitive data and information as it travels
over the network, a network operating system may
encrypt it to prevent unauthorized users from reading
the data.
 Encryption is the process of encoding data and
information into an unreadable form.
 When an authorized user attempts to read the data, it
is decrypted, or converted back into a readable form.
49

TYPES OF OPERATING
SYSTEMS
 Early operating systems were proprietary and
device -dependent.
 A device-dependent program is one that runs only on a
specific type or brand of computer.
 Proprietary software is privately owned and limited to a
specific computer model.
 The trend today is toward device-independent operating
systems that will run on computers provided by a variety of
manufacturers.
 Three basic categories of operating systems exist today.
 They are stand-alone OS, network OS, and embedded OS.
50

Stand-alone operating
systems
 A stand-alone operating system is a complete
operating system that works on a PC.
 Examples of popular stand-alone operating
systems include:
 Mac OS X, UNIX, Linux, MS-DOS and
Windows (XP, Windows Vista, Windows 7,
Windows 8, etc.).
51

Mac OS
 Macintosh operating system was released in
1984 with Apple’s Macintosh computers.
 Mac OS X includes features such as a GUI,
multitasking, large photo-quality icons,
 built-in networking support, email, online
shopping, enhanced speech recognition,
 CD burning, and enhanced multimedia
capabilities.
52

UNIX
 UNIX is a multitasking operating system developed
in the early 1970s by scientists at Bell Laboratories.
 Some versions of UNIX have a command-line
interface, and others offer a graphical user interface.
 Power users often work with UNIX because of its
flexibility and power.
 Manufacturers such as Sun and IBM often sell
personal computers and workstations with a UNIX
operating system.
54

Linux
 Linux is one of the fastest growing operating systems.
 Linux is a free, open source, UNIX-like operating system.
 Open source software means its code is provided for
use, modification, and redistribution. It has no
restrictions from the copyright holder.
 Some versions of Linux are command-line. Others are
GUI.
 Linux comes with very many utilities and applications
such as open office.
 A Live CD of Linux allows users to boot from it and
preview the operating system without installing it.
55

MS-DOS
 In the early 1980s, Bill Gates’ Microsoft Corporation
introduced DOS (Disk Operating System) as its first
operating system for IBM PCs.
 DOS originally used a command-line interface.
 Later versions of DOS included both command-line
and menu-driven user interfaces.
 Today, DOS is rarely used because it does not offer a
graphical user interface and it cannot take full
advantage of modern computer microprocessors.
56

57
US_Navy_Specialist_uses_the_existing_DOS-based
_food_service_management_system _2011

Microsoft Windows
 Microsoft introduced an operating environment
named Windows 1.0 on November 20, 1985.
 It was Microsoft's first attempt to implement a multi-
tasking graphical user interface-based operating
environment on the PC platform.
 Since then, Many versions have been released, each
with various new innovative features and functions.
 These include Windows 2.0, Windows 95, 98, Me,
Windows NT 3.1, Windows 2000, Windows XP,
Windows Vista, Windows 7 and the new Windows 8.
58

61
Windows 8 Start Screen
(To replace the start menu)

Network Operating Systems
 A network operating system (NOS) is an operating
system that supports a network and typically resides
on the server.
 Some stand-alone OS systems include networking
capability.
 However, network operating systems are designed
specifically to support all sizes of networks.
 Examples of network operating systems include
Windows Server 2003, 2008, Solaris, and NetWare,
UNIX server, and Linux server.
62

Embedded Operating
Systems
 An embedded operating system is an operating
system that resides on ROM chips and typically
used on handheld computers and small
devices.
 Popular embedded operating systems today
include Windows Embedded CE, Windows
Mobile, Palm OS, Embedded Linux, and
Symbian OS.
63

Factors to consider when
choosing an operating system
 When choosing an operating system for a computer
the following factors may be considered:
 The type of computer in terms of size and make.
Operating systems are available for all sizes of
computers.
 The hardware configuration of the computer such as
the memory capacity, processor speed and hard disk
capacity should meet the required minimum
requirements for a the operating system to run well.
65

 The application software to be installed on the
computer should be supported by the operating
system. For example Microsoft Office 2010 cannot
run on Windows 2000.
 The operating system should be user friendly. This
depends on the skills of the intended users of the
computers.
 The operating system should have adequate
information and help guides for user reference.
66

 The cost of the operating system.
 Reliability and security provided by the
operating system.
 The number of processors and hardware
devices it can support.
 The number of users it can support
 The availability of basic utilities and accessory
programs within the operating system.
67

Utility Software
 Utility software refers to system software designed to
analyze, optimize and maintain a computer in good
working conditions.
 Utility software usually focuses on how the computer
system operates.
 Although operating systems typically include some
built-in utilities, many stand-alone utility programs
are available.
 Examples include Anti virus utility, Screen Saver
utility, File compression utility, and Other utilities.
68

1. Anti virus utility
 A computer virus, is damaging program that
affects a computer negatively by altering the
way the computer works without the user's
knowledge or permission.
 Once a virus is in a computer, it can spread
throughout and damage your files and OS.
 Anti virus utilities are programs that scan for
computer viruses, remove, disinfect and repair
damaged files.
69

2. Screen Saver Utility
 SCREENSAVERS were originally designed to
prevent phosphor burn-in (ghosting) on CRT
monitors,
 A screen saver is a program that automatically fills
the computer’s VDU (Visual Display Unit) with
moving images or patterns when the computer is
not in use.
 Currently, screensavers are used primarily for
entertainment, advertising or security purposes.
70

3. File compression utility
 A file compression utility shrinks the size of a file. A
compressed file takes up less storage space than the
original file.
 Compressed files, sometimes called zipped files,
usually have a .zip extension.
 Attaching a compressed file to an e-mail message
reduces the time needed for upload and download.
 When you download a compressed file, you must
uncompress it to restore it to its original form.
71

Other utility software
categories
4. BACKUP utilities can make a copy of all
information stored on a disk, and restore
either the entire disk (e.g. in an event of disk
failure) or selected files (e.g. in an event of
accidental deletion).
5. DATA COMPRESSION utilities output a shorter
stream or a smaller file when provided with a
stream or file.
72

Utility software categories
(cont)
6. DISK CHECKERS can scan the contents of a hard disk to
find files or areas that are corrupted in some way, or were
not correctly saved, and eliminate them for a more
efficiently operating hard drive.
7. DISK CLEANERS can find files that are unnecessary to
computer operation, or take up considerable amounts of
space. Disk cleaner helps the user to decide what to delete
when their hard disk is full.
8. DISK COMPRESSION utilities can compress the contents of
a disk to small amounts of memory. They also uncompress/
expand the compressed files.
73

(cont)
9. DISK DEFRAGMENTERS can detect computer
files whose contents are broken and spread
across several locations on the hard disk, and
move the fragments to one location to increase
efficiency.
10.DISK PARTITIONS can divide an individual drive
into multiple logical drives, each with its own file
system which can be mounted by the operating
system and treated as an individual drive.
74

(cont)
11.ARCHIVE utilities output a stream or a single file
when provided with a directory or a set of files.
Archive suites, at times include compression and
encryption capabilities.
12.CRYPTOGRAPHIC utilities encrypt and decrypt
streams and files.
13.REGISTRY CLEANERS clean and optimize the
Windows registry by removing old registry keys that
are no longer in use.
75

(cont)
14. FILE MANAGERS provide a convenient method
of performing routine data management tasks,
such as deleting, renaming, cataloging, moving,
copying, merging, generating files and
modifying data sets.
15. MEMORY TESTERS check for memory failures.
16. NETWORK utilities analyze the computer's
network connectivity, configure network
settings, check data transfer or log events.
76

(cont)
17.A SPYWARE REMOVER is a utility that detects and
deletes spyware and other similar programs.
 Spyware is a program placed on a computer without
the user's knowledge that secretly collects
information about user, often related to Web
browsing habits.
18.INTERNET FILTERS are utilities that remove or
block certain items from being displayed.
 Four widely used filters are anti-spam programs, Web
filters, phishing filters, and pop-up blockers.
77

(cont)
19.SYSTEM PROFILERS provide detailed
information about the software installed and
hardware attached to the computer.
20.SORTING UTILITY for organizing files in any
chosen order.
21.MERGE UTILITY for Merging or combining
different files in one.
22.HEX EDITORS directly modify the text or data of a
file a program.
78

(cont)
23. A SEARCH UTILITY is a program that
attempts to locate a file on your computer
based on criteria you specify.
24. A PERSONAL FIREWALL is a utility that
detects and protects a personal computer
from unauthorized intrusions.
25. An UNINSTALLER is a utility that removes a
program, as well as any associated entries in
the system files.
79

(cont)
26. A DIAGNOSTIC UTILITY compiles technical
information about your computer's hardware
and certain system software programs and
then prepares a report outlining any
identified problems.
27. SYSTEM MONITORS for monitoring
resources and performance in a computer
system.
28. … e.t.c….
80

Programming Languages
 A programming language is a notation for writing computer
software.
 Programming languages are can be used to create the
procedures and specifications of a computation or algorithm.
 NB: Examples of popular programming languages include:
 FORTRAN (FORmular TRANslator)
 BASIC (Beginners’ All-purpose Symbolic Instruction Code)
 Visual BASIC
 COBOL (COmmon Business-Oriented Language)
 C and C++
 Java
 Pascal, Perl, e.t.c.
81

 When computers execute programs written in
languages such as BASIC, C, Java, etc., the
computer must convert these humanly readable
instructions into a form it can understand.
 System software contains the special language
translation programs that translate these
higher-level language programs into machine
language that the computer can execute.
82

(cont)
 System software includes a compiler,
interpreter, and assembler.
 The program in the high-level language before
translation into machine language is called
source code.
 A compiler translates source code into
machine binary code called object code.
83

(cont)
 Some programming languages such as BASIC
do not use a compiler but an interpreter.
 An interpreter translates each source code
statement one at a time into machine code and
executes it.
 An assembler is similar to compiler, but it is
used to translate only assembly language into
machine code.
84

NEXT UNIT: 3. APPLICATION
SOFTWARE
END OF UNIT TWO: SYSTEM
SOFTWARE
85

302_System_Software_082747 by Abraham.ppt

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