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Dec 10, 2013 (3 years and 11 months ago)

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Operating Systems

Topics


OS Definition


Types of PC OS


Functions of OS


Terms and Concepts


DOS Commands


Operating Systems


Operating System



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

Windows
98

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


Examples of PC OS (Cont.)

Linux

Chrome OS

OS/2

Examples of Mobile Devices OS

-
iOS

5

-
iOS

6

-
iOS

7


-
Windows 7 m

-
Windows 8 m


Microsoft

-
Android
4
Ice Cream Sandwich

-
Android
4.2
Jelly Beans

-
Android
4.3
Kit Kat


Mobiles OS

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.


4.
Communication
:

it is the ability to a computer to
communicate with other computers to transfer programs and
data.

5.
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).

6.
Program Execution Environment
:
OS loads the program
into the memory and manage program execution

7.
Security
:
make
sure that
only authorized users
can access
computer.


Functions of the operating systems (cont.)


Operating System

Input/Output

Accounting

Memory and storage


Management

Communication

Security

Time Sharing

Program


Execution Environment

Functions of the operating systems as a diagram

Zuhair Al Sofi

10

Components of an operating
system


1.
The
Executive
or
Supervisor

2.
The Command Interpreter

3.
The Internal Commands

4.
The External Commands



Zuhair Al Sofi

11

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

12

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.

Components of an operating system

(cont.)

Zuhair Al Sofi

13

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


Components of an operating system

(cont.)

OS Terms and Concepts


Graphical User Interface GUI:


The method by which a person communicates
with a computer. It uses a mouse, touch pad,
icons to interact with the computer.


Shell:


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:


Similar to a standard OS, except that the NOS
is optimized to provide services to other
machines on the network.

OS Terms and Concepts


Cooperative Multitasking:


A multitasking method that depends on the
application itself to be responsible for using
and then freeing access to the processor.


Preemptive Multitasking:


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:


The ability of a single application to have
multiple requests in to the processor at one
time.

OS Terms and Concepts


Virtual Memory ( swapping or paging file):
A+ book p
53

How


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/swapped into main memory
( RAM).

Why


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.

Disadvantages


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

Ver
: used to display the windows version.

CD
: Change the current directory

Format
: used to format a disk.

MD
: create directory

Cls
: used to clean the screen.

Rd
: delete file or directory

Chkdsk
: checks a disk and display status
report.

Edit
: create file

Fdisk:

it enables you to create Hard disk
partions

Copy
: copy one or more files from one
place to another


Date
: display or change the date

Del
: delete one or more files


Time
: Used to display or change the time

Label
:

Creates, changes, or deletes
the volume label of a disk.