Operating Systems
Coordonator: Dr. Z. Pólkowski
Siposs Arnold Konrad
Description
• An operating system or OS is a software that enables the
computer hardware to communicate and operate with the
computer software. Without a computer operating system, a
computer and software programs would be useless.
• For hardware functions such as input, output and memory
allocation, the operating system acts as an intermediary
between programs and the computer hardware, although the
application code is usually executed directly by the hardware
and frequently makes system calls to an OS function or be
interrupted by it
Source: http://en.wikipedia.org/wiki/Operating_system
Basic information
• The operating system is also responsible for security,
ensuring that unauthorized users do not access the system.
Source: http://www.webopedia.com/TERM/O/operating_system.html
Types of OS
• As computers have progressed and developed, so have the
operating systems. Below is a basic list of the types of
operating systems and a few examples of operating systems
that fall into each of the types
• There exist four types of operating systems which are based
on the type of computer they control and the sort of
applications they support.
Source: http://www.computerhope.com/os.htm
Single-user, Single-task OS
• This type manages the computer so that one user can
effectively do one thing at a time.
• This type is especially owrking on mobiel phones.
Source: http://senseoftech.com/how-to-understand-the-operating-system-of-your-computer/
Multi-user, Multi-task OS
• Allows two or more users to run programs at the same time.
Some operating systems permit hundreds or even thousands
of concurrent users.
Source: http://mylinuxexplore.blogspot.com/2012/06/light-linux-distribution-series-puppy.html
Real time OS
• Real Time OS are used to control machinery, scientific
instruments, and industrial systems. There is typically very
little user interface capability. Resources are managed so that
a particular operation executes precisely the same every
time.
Source: http://mylinuxexplore.blogspot.com/2012/06/light-linux-distribution-series-puppy.html
Single-user, Multi-tasking OS
• This is the type of operating system most desktops and
laptops use today. Microsoft’s Windows and Apple’s MacOS
are both examples of operating systems that will let a single
user have several programs in operation at the same time.
Source: http://logos.wikia.com/wiki/Mac
Process management
Source: https://www.youtube.com/watch?v=1fwxHAf1E88
Description
• Process management is an integral part of any modern day
operating system.
• The OS must allocate resources to processes, enable
processes to share and exchange information, protect the
resources of each process from other processes and enable
synchronization among processes.
• To meet these requirements, the OS must mantain a data
structure for each process, which describes the state and
resources ownership of that process and which enables the
OS to exert control over each process.
Source: http://www.slideshare.net/orven_neu/process-management-in-os-8374196
What is process?
Execution of a program is called process.
Process State
A Process in execution will have to pass through different stages
viz., New, Ready,Running, Waiting and Termination.
New: A Process which is just created will enter into this stage.
Ready: A Process waiting for the CPU is in this stage.
Running: The Process which is currently using CPU to execute its
instruction is in this stage.
Terminated: The Process that finishes its execution will be
terminated.
Source: http://www.tutorialspoint.com/operating_system/os_processes.htm
Process state
Source: http://www.siasat.com/gate/content/process-management-subject-operating-system
Threads
• In computer science, a thread of execution is the smallest
sequence of programmed instructions that can be managed
independently by a scheduler, which is typically a part of
the operating system.
• The implementation of threads and processes differs
between operating systems, but in most cases a thread is a
component of a process. Multiple threads can exist within the
same process and share resources such as memory, while
different processes do not share these resources.
Source: http://en.wikipedia.org/wiki/Thread_(computing)
OS for parallel computers
• When available computers are incapable of providing a
sufficient computing power for solving the arising tasks, while
purchasing new and powerful equipment is economically
infeasible, the only way to gain additional computing power is
to parallel the computational process between several
interconnected computers. The idea of parallel distributed
computing has been studied in cybernetics since early sixties.
• Modern operating systems support parallel execution of
processes on multiprocessor and uniprocessor computers.
For this purpose an operating system provides process
synchronization and communication facilities.
Source: https://www.cs.utah.edu/~aburtsev/doc/OS_for_Parallel_Computing_IASA2001.pdf
Operating Systems classification
Source: http://homepages.uel.ac.uk/u0524584/diffos.htm
Network Operating Systems
• Abbreviated as NOS, a network operating system includes
special functions for connecting computers and devices into
a local-area network (LAN). Some operating systems, such
as UNIX and Mac, have networking functions built in.
• The term network operating system is generally reserved for
software that enhances a basic operating system by adding
networking features. Novell Netware, Artisoft's
LANtastic, Microsoft Windows Server, and Windows NT are
examples of a NOS.
Source: http://www.webopedia.com/TERM/N/network_operating_system_NOS.html
Multiprocessor Operating Systems
• Multiprocessor Operating System refers to the use of two
or more central processing units (CPU) within a single
computer system. These multiple CPU’s are in a close
communication sharing the computer bus, memory and other
pheripheric devices. These systems are referred as tightly
coupled systems.
Source: http://ecomputernotes.com/fundamental/disk-operating-system/multiprocessor-operating-system
Distributed Operating Systems
• Distributed Operating System is a model where
distributed applications are running on multiple computers
linked by communications. A distributed operating system is
an extension of the network operating system that supports
higher levels of communication and integration of the
machines on the network.
• This system looks to its
users like an ordinary
centralized operating system
but runs on multiple,
independent central
processing units (CPU’s).
Source: http://ecomputernotes.com/fundamental/disk-operating-system/distributed-operating-system
OS Specification’s
Source: http://www.slideshare.net/kapil078/cmp104-lec-5-software-and-operating-system
Memory management
• Memory management is the act of managing computer
memory at the system level. The essential requirement of
memory management is to provide ways to dynamically
allocate portions of memory to programs at their request, and
free it for reuse when no longer needed. This is critical to any
advanced computer system where more than a single
process might be underway at any time.
Source: http://en.wikipedia.org/wiki/Memory_management
Allocation of free space
• Free space is segment of capacity space of a partition which
is not in use. It is the rest stored space of a partition. You can
use free space to store your data directly.
• However, unallocated space can’t be used directly. This is
the difference between free space and unallocated space.
Source: http://www.disk-partition.com/resource/allocate-free-space.html
Allocation of free space
Source: http://www.disk-partition.com/resource/allocate-free-space.html
References
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http://www.wikihow.com/Make-a-Computer-Operating-System
https://www.clinton.edu/repository/5043.pdf
http://pkenmore.wikispaces.com/Network+Operating+System+(NOS)
http://ecomputernotes.com/