Operating Systems

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14 Δεκ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Operating Systems

System Software, functions of an operating system

The Operating System


The Operating System is also known as
System Software.



All computers must have an operating
system in order to work



The OS is responsible for all the functions
of hardware and also software

Functions of an Operating System


GUI




Device

Drivers



Security



Networking


Disk

Managem
ent

(File
Systems)


Memory

Management


Process

Management


Operating

System

Process Management


A multitasking OS allows the computer to
perform many different tasks(processes) at
the same time



The CPU can only focus on one process at a
time. The OS tells the CPU to give each
process a very short time slice (time slot)



This happens very fast making


it seem like the processes


are occurring at the same time


Memory Management


A computer has different memory types
it could use; memory registers, cache,
RAM and disk storage.



The OS is responsible for checking;


which memory if free


which memory is to be


allocated and de
-

allocated



how to swap between the


main memory and secondary memory

Memory Management


When the OS swaps between main
memory and secondary memory we call
this Virtual Memory management



Virtual memory creates a memory slot
acting as RAM when the RAM is too full



Virtual memory is much
slower than RAM

Disk Management / File Systems


Operating systems have different file
systems.



A file system is an organisation


of all the files and folders saved within the
computer



Each OS has a different file system hence
a different access system (notes page 29)



Networking


Most of the
OSs

today are capable of
using the universal TCP/IP (Transmission
Control Protocol/Internet Protocol)



This allows computers to communicate
with each other and be able to share
resources such as files and
hardware devices over a
network, such as Internet.

Security


The basic type of security an OS
offers is asking for a Username
and Password before a user can use
the OS



The OS could also limit certain users from
doing certain actions. This is known as level
access



The OS uses a Firewall to close certain
ports when using TCP/IP protocol

GUI


Graphical User Interface


Most operating systems use a GUI


Graphical User interfaces, which is more
user
-
friendly as it uses graphical
representations which the user can easily
understand.



A GUI's components are


Icons,


Menus,


Windows,


Toolbars ,


Buttons amongst others.


Windows GUI

Linux GUI

MAC GUI

Device Drivers


A device driver is software that is
responsible for the communication
between different hardware and the
computer.



Device drivers are used to let the OS
know how a specific hardware works as
with all the new advances in technology it
is impossible for the OS to know how
ALL types of hardware work