2. What is a Software?
Software is the general name given to
all the programs or set of instructions
that computers use to perform
different tasks.
3. Two Major Categories of Computer
Software:
System Software
Application Software
4. System Software
System software manages and
supports the resources and operations
of a computer system.
These resources include input/output
devices, the processor, storage
devices (primary and secondary) and
communication devices.
5. Types of System Software
1. Operating System
2. Utility Programs
6. Booting Process (what happens
when computer is turned on)
The first thing a computer has to
do when it is turned on is start up a
special program called an operating
system. ... Your computer knows how
to boot because instructions for
booting are built into one of its chips,
the BIOS (or Basic Input/Output
7. Booting Process
The process of starting or restarting a
computer is called ‘BOOTING’. When
turning on a computer that has been
powered off completely, you are
performing a COLD BOOT(simply
pressing the computer's power button
once to turn it off and then again to
turn it back on). A WARM BOOT is the
process of using the operating system
to restart a computer.
8. System Software
The most commonly used system
software is called operating system
Computer would not work without an
os
Popular OS include Windows XP,
Windows 2000, Windows Vista, UNIX,
LINUX
10. Types of OS
MS DOS
Windows 3.X,
Windows 95
Windows 98,
Windows ME
(Millennium
Edition)
Windows 2000
Windows XP
Windows NT
Apple operating
systems , Linux
and Unix
Windows VISTA
16. Types/Modes of processing
Do you recall learning that processing
involves accepting data & converting it
into output, or information. The data
will be collected & processed in many
ways, based on what you want to do.
Some may be processed immediately,
weekly or monthly. Here are some
ways in which you can do it!
17. Types/Modes of processing
Batch Processing – when data
collected is grouped together &
processed at a certain time such as
weekly, monthly (used by JPS, NWC)
18. Types/Modes of processing
Online processing – data is collected
& processed immediately, user
interacts directly with computer at
anytime through the IO devices (ATM,
online games, flight systems)
19. Types/Modes of Processing
Interactive processing - simplest way
to work on a system. You log in, run
commands which execute
immediately, and log off when you've
finished. You can use either the
command line or a graphical
environment
20. Types/Modes of Processing
Time sharing processing – method of
processing that allows many users to
use a computer system
simultaneously eg. more than one
users can request a file at the same
time
21. Types/Modes of Processing
Real-time processing – is the method
of inputting, processing & outputting
data continuously (without delay).
Eg. of RTP systems (anti-missile
systems, aeroplane landing control
system, flight simulation system,
electronic fund transfer system, ticket
22. Guess what, its your turn!
For each of the following tasks,
suggest an appropriate processing
mode:
controlling a robotic arm
monthly stock taking processing
checking criminal records
ATM transactions
resereving a movie
24. Parts of OS (Kernel)
Kernel is a program that makes up the
main part of the OS. The kernel is the
first part of the operating system to
load into main memory (RAM)
during booting (i.e., system startup
after the bootloader), and it remains
there for the entire duration of the
computer session because its services
are required continuously. Kernel
executes processes and handles
interruptions.
25. Parts of OS (Scheduler)
The part of the operating system that
initiates and terminates jobs
(programs) in the computer. Also
called a "dispatcher," it maintains a list
of jobs to be run and
allocates computer resources as
required
Schedulers keep all computer
resources busy by allowing multiple
users to share system resources
effectively
26. Parts of OS (Process
Manager)
Process Manager – enables
processes by allowing OS to allocate
resources to share and exchange
information, protect the resources of
each process from other processes
and enable synchronization among
processes
27. Parts of the OS
Shell – this is a program that acts as
an interface between the user & the
OS, it allows the user to enter
commands for the OS to execute
28. Parts of the OS
FAT- this refers to the way Windows
stores data on the hard drive. "FAT"
stands for "File Allocation Table,"
which keeps track of all your files and
helps the computer locate them on the
disk.
FAT 32 is an improvement to the
original FAT system, since it uses
more bits to identify each cluster on
29. Parts of the OS
Translator - computers understand
only binary language. Translator is a
software used to convert programs
into binary/machine language. Three
types are interpreter, compiler &
30. General Purpose OS &
Dedicated OS
The basic difference of using a
GPOS or a DOS lies in the nature of
the system i.e whether the system
is “time critical” or not!
A system can be of a single purpose
(DOS) or multiple purpose (GPOS)
31. GPOS (Multipurpose)
Personal computer (PC) is not a time
critical system
Multipurpose system (run many
applications at the same time)
A GPOS is used for
systems/applications that are not time
critical eg. Windows, Linux, Unix
32. GPOS(Multipurpose)
After pressing the SAVE button of a
finished document, there is no
particular time limit that the doc should
be saved within 5 seconds. It may
take several minutes (in some cases)
depending upon the number of tasks
and processes running in parallel
33. Dedicated OS
Dedicated OS
designed to be used in specific
systems
designed to operate on small
machines like phones
they operate with a limited number of
resources
they are very compact and extremely
efficient by design.
34. Dedicated OS cont’d
ensures a higher level of security
banks use dedicated operating system
to prevent cyber attacks on financial
transactions
Dedicated OS is custom made to do a
specific function at maximum
efficiency
35. Dedicated OS
Automated Teller Machines (ATM)
time critical system
ATM card user gets his money from
machine within 4/5 seconds after
confirmation (user will not wait 5
minutes at the ATM after he pressed
the confirm button, so ATM is a time
critical system)
36. Types of Dedicated OS
iOS 8 is the eighth major release of
the iOS mobile operating system
developed by Apple Inc.
37. Types of Dedicated OS
Mac OS is the computer OS for
Apple Computer's Macintosh line of
computers (latest version, Mac OS X
a desktop interface with some 3-D
appearance characteristics)
38. Functions of OS
Process Management „
Main Memory Management „
File Management „
I/O System Management „
Secondary Management „
Utility/Protection System
39. Functions of the OS
Starting a Computer
Providing a User Interface
Managing computer resources
Managing files and memory
Maintaining Security
Managing Tasks
Multiprocessing
41. Process Management
Process management – allocates time
for processes to use the CPU, keeps a
check on other processes that are
waiting to use the CPU, or signals
when CPU is available
42. Main Memory Management
When program or data too large to fit
into main memory, a method called
virtual memory can be used to split the
program into manageable blocks. The
required blocks are split between main
memory & secondary storage, giving
the impression that the computer has
expanded its memory to
accommodate the data
43. File Management
Files need to be saved, copied,
renamed & deleted. A file manager
checks the amount of memory needed
to perform these tasks, & manages
the organisation of the files in
44. I/OS System Management
Since each device has a program
called a driver that allows the device
to communicate with the computer, the
flow of information among devices
must be managed & coordinated. The
use of buffers is one way to manage
these devices.
45. Secondary Management
Since main memory (primary storage)
is volatile and too small to
accommodate all data and programs
permanently, the computer system
must provide secondary storage to
back up main memory.
The operating system is responsible
for the following activities in
connection with disk management: –
free space management, storage
allocation, disk scheduling
46. Utility Software
This is a specialized software that
supports the OS in housekeeping
tasks to increase the efficiency of the
computer system
Protect & maintain the system
software examples include protect
software against damage cause by
viruses, making copies of files (back
up) software
47. Functions of Utility Programs
File defragmentation: When files are
stored in a new computer or hard disk
they are stored next to one another
(contiguously). After using your
computer for a while you will probably
have deleted old files and added new
ones. After a while parts of a file are
scattered all over your hard disk. The
process of reducing the fragmentation
is known as defragmentation.
51. Functions OS cont’d
Hardware Control
The OS makes communication possible
between the peripheral devices & the
system unit
Software Control
Manages all software applications,
games or other programs on the
computer
52. Functions OS cont’d
Operating system provides user with
password protection to prevent
unauthorised access
Provides backup & recovery routines
in case of system failure
53. File Management
Windows Explorer is a file
management utility which organises
files on storage devices such as
diskettes, hard disk & CD-ROM
File management provides a lists of
the filenames, type of files, date &
time the files were created & file size
54. File Management terms….
File – every
document that you
use is called a file
Folder – used to
keep a group of
files together
55. File Management terms….
Drive – Computers have several
storage devices such as hard drive,
floppy drive, USB drive or CD drive.
Contains file & folders
Each drive is given a specific drive
letter to distinguish them from each
other
Floppy drive A/B, Hard drive C etc,
Network drive further down alphabet
eg. M, O
57. File management terms
cont’d…
Path – to locate a file, you may have
to select the drive and then one or
more folders.
This sequence to get to specific
folder/file is called a path
First select the drive (path starts with
drive letter)
File/folder name comes last in the
path
58. File management terms
cont’d…
C:CXCUnit1.doc means that the file
Unit1.doc is found in the CXC folder
located on drive C.
The backslash is used to separate
the file, folder or drive name
59. How to choose file names
A file has two parts:
FILE NAME (name given to the file by
user)
EXTENSION(file name extension is
a set of characters added to the end of
a file name that determine which
program should open it…default)
60. Sample File Extensions
unit.1.doc (word processing file)
device.com (command file)
index.htm (document from internet)
config.sys (system file)
Never use the following characters in a
file name
. , / : ; [ ] “ | =
61. User Interface
The OS support the user interface of
the computer. A user interface is the
way in which a user interacts with a
computer system. It may be software
interface (command driven interface,
menu driven interface & graphical user
interface GUI) or hardware interface
(touch screen, special keyboards,
sensors).
62. Command Driven/Line
Interface
require user to type in commands
using special language
difficult for new computer users to
understand
Microsoft Disk Operating System (MS-
DOS)
63. Menu Driven Interface
developed because some people
found it difficult to understand
command driven
Gives users a list of command options
called a menu (easy to understand)
Options are chosen using keyboard or
mouse
64. Graphical User Interface
(GUI)
Provide users with Windows, Icons,
Menus, Pointers (WIMP)
GUI provides users with toolbars, drag
& drop, labels, on screen assistants,
buttons)
Main interfacing device is mouse
65. Device Configuration
Configuration is the arrangement or
the process of making the
arrangement of the parts that make up
a whole.
a device driver is a small program
which tells the OS how to
communicate with a specific device
eg. mouse, printer etc.
If a new device is attached to the
computer its driver must be installed
66. Device Configuration
Some OS support Plug & Play which
means the OS automatically
configures new devices when they are
installed
Some OS requires users to configure
systems manually
Go google here…..
http://searchenterprisedesktop.techtar
get.com/tip/Device-drivers-Installation-
and-configuration
67. Network Connections
A network OS is designed to allow
shared file and printer access among
multiple computers in a network, to
enable the sharing of data, users,
groups, security, applications, and
other networking functions over a local
area network (LAN)
69. Monitoring Performance
OS contains a performance monitor
program that assess & reports
information about various computer
resources & devices
Users can monitor disks, processor,
memory & network usage
Performance monitor identifies,
reports & tries to resolve problems
with resources (if running slow PM will
indicate memory is being used to its
