Download Functions of the operating systems

Operating Systems
Topics
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OS Definition
Types of PC OS
Functions of OS
Terms and Concepts
DOS Commands
Operating Systems
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Operating System
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Is a set of programs which manage all
operations of the computer system,
and enables the user to interact with
the hardware ‘HW’.
It provides a consistent environment
for other software to execute
commands.
Examples of PC OS
Microsoft
Windows Me, NT, 2000, XP, Vista, 7, 8 (Client)
Windows 2000, 2003 , 2008, 2012 (Server )
Macintosh
Mac OS X snow Leopard
Mac OS X Lion
Mac OS X Mountain Lion
Windows 98
Examples of PC OS (Cont.)
OS/2
Chrome OS
Linux
Examples of Mobile Devices OS
Mobiles OS
-iOS 5
-iOS 6
-iOS 7
-Android 4 Ice Cream Sandwich
-Android 4.2Jelly Beans
-Android 4.3 Kit Kat
Microsoft
-Windows 7 m
-Windows 8 m
Functions of the operating systems
1.
Input and output: allows computer to display and get
data from the I/O devices to interact with users.
2. Memory and secondary storage management:
1. allows the user to organize their data on secondary
storage into files & folders
2. also manages the use of main memory by splitting
main memory into two parts (user area, system area).
3. Time sharing: operating system can allow more than
one user to work on the same computer, and run more
than one program at the same time.
Functions of the operating systems (cont.)
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5.
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Communication: it is the ability to a computer to
communicate with other computers to transfer programs and
data.
Accounting: this is to keep track of what each user has done
on the computer, to bill each for the resources used(if
necessary). (for each user a separate account).
Program Execution Environment : OS loads the program
into the memory and manage program execution
Security: make sure that only authorized users can access
computer.
Functions of the operating systems as a diagram
Memory and storage
Management
Input/Output
Security
Operating System
Program
Execution Environment
Time Sharing
Communication
Accounting
Components of an operating
system
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2.
3.
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The Executive or Supervisor
The Command Interpreter
The Internal Commands
The External Commands
Zuhair Al Sofi
10
Components of an operating
system
1. The executive or supervisor:
 this is the main part of the operating system.
 it is a memory resident program which stays in RAM as long
as the computer is on.
 it supervises all operations like data storage and memory
access.
The supervisor is loaded into main memory at
switch-on time by a small program in ROM
called the Bootstrap loader. this program
looks for the supervisor program on the first
track on the disk(boot sector). It loads the
supervisor into the ram and runs it, this
process is called(Booting the system).
Zuhair Al Sofi
11
Components of an operating system
(cont.)
1. The command interpreter:
 each operating system has a set of
commands, each command has a valid
syntax.
 the command interpreter interprets each
command issued by the user and calls for the
appropriate program from the operating
system to carry out the command.
 If there is a syntax error, it will notify the user
and may lead the user how to handle it.
Zuhair Al Sofi
12
Components of an operating system
(cont.)
3. The internal commands:
 those are the mostly used commands set,
they remain in the ram.
 Examples: Dir, Cd, Ren, …etc.
4. The external commands:
 Large and less frequently used commands.
 They kept in the disk to save the ram space,
they will be loaded in ram once they are
used.
 Examples: Format, Diskcopy, Fdisk ..etc
Zuhair Al Sofi
13
OS Terms and Concepts
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Graphical User Interface GUI:
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Shell:
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The method by which a person communicates
with a computer. It uses a mouse, touch pad,
icons to interact with the computer.
A program that runs on top of the OS and
allows the user to issue commands through a
set of menus or GUI.
Networking Operating System NOS:
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Similar to a standard OS, except that the NOS
is optimized to provide services to other
machines on the network.
OS Terms and Concepts
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Cooperative Multitasking:
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Preemptive Multitasking:
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A multitasking method that depends on the
application itself to be responsible for using
and then freeing access to the processor.
A multitasking method in which the OS allots
each application a certain amount of processor
time and then forcibly takes back control and
gives another application or task access to the
processor.
Multithreading:
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The ability of a single application to have
multiple requests in to the processor at one
time.
OS Terms and Concepts
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Virtual Memory ( swapping or paging file):
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A+ book p53
Modern applications requires huge memory to run.
Also a lot of programs can work at the same time, so
virtual memory takes the advantage of the vast nature of
recent computer programs.
It uses what is called a swap file, or paging file.
A swap file is actually hard drive space into which idle
pieces of programs are placed, while other active parts of
programs are kept in or swapped into main memory (
RAM).
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The disadvantage here is that it is not as fast as the real
memory.
Setting up Win XP virtual memory
Examples of DOS Commands
A+ book p 384-386
CD: Change the current directory
Ver: used to display the windows version.
MD: create directory
Format: used to format a disk.
Rd: delete file or directory
Cls: used to clean the screen.
Edit: create file
Chkdsk: checks a disk and display status
report.
Copy: copy one or more files from one
place to another
Fdisk: it enables you to create Hard disk
partions
Del: delete one or more files
Date: display or change the date
Label : Creates, changes, or deletes
the volume label of a disk.
Time: Used to display or change the time