Transcript SYSTEM SOFTWARE

SYSTEM SOFTWARE
Prepared by: Mrs. Careene McCallum-Rodney
INTRODUCTION
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There are 2 types of software:
System Software
 Application Software
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What is the major purpose of each type of
software?
Application software is designed to help people
perform a certain type of work.
 System software is any software required to support
the production or execution of application programs
but which is not specific to any particular application.
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Name the 2
main types
of system
software
Types of
SYSTEM
SOFTWARE
Operating System
Utility Programs
What are
the
functions
of the O/S?
OPERATING SYSTEM
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An Operating System (commonly abbreviated OS and
O/S) is the software component of a computer system
that is responsible for the management and
coordination of activities and the sharing of the
limited resources of the computer.
An operating system is a program designed to run
other programs on a computer.
Operating systems are responsible for everything
from the control and allocation of memory to
recognizing input from external devices and
transmitting output to computer displays.
FUNCTIONS OF O/S
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PROCESS MANAGEMENT
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NOTE: A process is the unit of work in a system.
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The creation and deletion of both user and system
processes
The suspension and resumption of processes
The provision of mechanisms for process
synchronization
The provision of mechanisms for process
communication
The provision of mechanisms for deadlock handling
(deadlock is a situation in which each process in a set
of processes is waiting for an event that only another
process in the set can cause. since all the process are
waiting, the system enters a deadlocked condition
MEMORY MANAGEMENT
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Keep track of which parts of memory are
currently being used and by whom.
Decide which processes are to be loaded into
memory when memory space becomes available.
Allocate and de-allocate memory space as needed.
FILE MANAGEMENT
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Creation and Deletion of files
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Creation and Deletion of directories
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Support of primitives for manipulating files and
directories
Mapping of files to secondary storage
Backup of files on stable (non-volatile) storage
media.
DEVICE MANAGEMENT
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A program, as it is running, may need additional resources
to proceed. Additional resources may be more memory, tape
drives, access to files, and so on. If the resources are
available, they can be granted, and control can be returned
to the user program; otherwise, the program will have to
wait until sufficient resources are available.
Files can be thought of as abstract or virtual devices. Thus,
many of the system calls for files are also needed for
devices.
If there are many multiple users of the system, we must
first request the device, to ensure exclusive use of it. After
we are finished with the device, we must release it.
Once the device has been requested (and allocated to us),
we can read, write, and (possibly) reposition the device.
SECURITY
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Security at the Operating System level is
implemented at several levels ranging from password
for access to the system to the isolation of concurrent
processes running on the system.
The file system also provides some degree of
protection.
The areas of security to be focused on are:
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Authentication using User IDs, Passwords, and Lock-words
Access control list
File Encryption
File compression
Activity logs
NETWORK
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In a network operating system, the users are
aware of the multiplicity of machines, and need
to access these resources (meaning both
hardware and software) by either logging into the
appropriate remote machine, or transferring data
from the remote machine to their own machine.
USER INTERFACE
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This is the portion of software that defines how a
user interacts with a computer, including how
the user enters data and instructions and how
information is displayed on screen.
This is a mediator between the user and the
computer.
User Interfaces provides a means of:
Input - allowing the users to manipulate a system
 Output - allowing the system to indicate the effects
of the users' manipulation
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USER INTERFACE
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The OS is responsible for the interface displayed to users. An
interface can be:
Command Line
Interface
Menu Driven
Interface
Graphical User
Interface
COMMAND LINE VS GUI
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CLASSIFICATION OF OS
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Multi-user:
Allows two or more users to run programs at the same time.
Some operating systems permit hundreds or even thousands of
concurrent users.
Multiprocessing:
Supports running a program on more than one CPU.
Multitasking:
Allows more than one program to run concurrently.
Multithreading:
Allows different parts of a single program to run concurrently.
Real time:
Responds to input instantly. General-purpose operating
systems, such as DOS and UNIX, are not real-time.
Types of
SYSTEM
SOFTWARE
Operating System
Utility Programs
UTILITY SOFTWARE
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These are software that help the user to do some tasks that
are not provided by the Operating System. Now days, they
usually come with the Operating System but they are
developed by different companies.
Functions of utility software.
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When your data has been destroyed in any way, you can
recover and restore the data by using data recovery
utility software.
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Anti-virus software are also utility programs that can
help protect your computer from dangerous viruses that
can damage your system. Examples of those utilities are
MacAfee anti-virus, Avira anti-virus, web scan, Norton
anti-virus, AVG, and so on.
UTILITY SOFTWARE (CONT)
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Functions (cont):
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We also have back-up utility software that can help back up
you data so that incase your hard disk damages, you can still
have your data back. An example of this utility is Colorado
scheduler.
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Sometimes your data can take up a lot of space on your hard
disk and leave a very less space available. You can use a data
compression utility to compress your data and create more
space on your hard disk. An example of this utility is pk zip.
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Sometimes, files can also be scattered in bits on your hard
disk and therefore making it difficult to access them. You can
therefore defragment those files by running a disk
defragmenter utility. The utility usually brings the files
together and arranges them in an adjacent manner therefore
making it easier to access the files.