An operating system – commonly referred to as an OS – is a set
of computer programs that manage the hardware and software
resources of a computer. The OS processes electronic devices with a
rational response to commands that are approved by the system.
At the foundation of all system software, an operating system
performs basic tasks like controlling and allocating memory,
prioritizing system requests, controlling input and output devices,
facilitating the network, and managing files. The OS can also provide
a graphical user interface for higher functions. Essentially, the OS
forms a platform for other system software as well as application
software.
The operating system is the most important program that runs
on a computer. Without an operating system, your computer would
not work. It would not be able to process requests for print, simple
calculations, or any other function. It is really the brain that runs the
equipment.
For larger system, the OS has great responsibilities than with a
PC. In larger systems, the operating system is kind of like a traffic
cop. It makes sure that different users and programs running at the
same time on different systems don’t interfere with each other. It also
acts as a security guard making sure that unauthorized users are not
able to access the system.
There are four classifications of a computer operating system.
They are:
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
Multi-Processing: Supports running a program on more than
one CPU
Multi-Tasking: Allows more than one program to run
concurrently
Multi-Threading: 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.
Operating systems provide a software platform on top of which
other programs, called application programs, can run. The application
programs must be written to run on top of a particular operating
system.
Your choice of operating system, therefore, determines to a
great extent the applications you can run. For PCs, the most popular
operating systems are DOS, OS/2, and Windows, but others are
available, such as Linux.
In any device that has an operating system, there's usually a
way to make changes to how the device works. This is far from a
happy accident; one of the reasons operating systems are made out of
portable code rather than permanent physical circuits is so that they
can be changed or modified without having to scrap the whole device.
For a desktop computer user, this means you can add a new
security update, system patch, new application or often even a new
operating system entirely rather than junk your computer and start
again with a new one when you need to make a change.
As long as you understand how an operating system works and
know how to get at it, you can in many cases change some of the
ways it behaves. And, it's as true of your cell phone as it is of your
computer.
So, essentially, when you turn on your computer, the first
program is a set of instructions kept in the computer’s read only
memory. These instructions examine the system hardware to make
sure everything is functioning properly. This power-on self test check
the CPU, the memory, and the basic input/output systems (BIOS) for
errors and stores the result in a special memory location.
Once the test has successfully completed, the software loaded in
ROM (sometimes called the BIOS or firmware) will begin to activate
the computer's disk drives. In most modern computers, when the
computer activates the hard disk drive, it finds the first piece of the
operating system: the bootstrap loader.
The bootstrap loader is a small program that has a single
function: It loads the operating system into memory and allows it to
begin operation. In the most basic form, the bootstrap loader sets up
the small driver programs that interface with and control the various
hardware subsystems of the computer.
It sets up the divisions of memory that hold the operating
system, user information and applications. It establishes the data
structures that will hold the myriad signals, flags and semaphores that
are used to communicate within and between the subsystems and
applications of the computer. Then it turns control of the computer
over to the operating system.
It might be helpful for you to know the history of operating
systems.
of computer programs that manage the hardware and software
resources of a computer. The OS processes electronic devices with a
rational response to commands that are approved by the system.
At the foundation of all system software, an operating system
performs basic tasks like controlling and allocating memory,
prioritizing system requests, controlling input and output devices,
facilitating the network, and managing files. The OS can also provide
a graphical user interface for higher functions. Essentially, the OS
forms a platform for other system software as well as application
software.
The operating system is the most important program that runs
on a computer. Without an operating system, your computer would
not work. It would not be able to process requests for print, simple
calculations, or any other function. It is really the brain that runs the
equipment.
For larger system, the OS has great responsibilities than with a
PC. In larger systems, the operating system is kind of like a traffic
cop. It makes sure that different users and programs running at the
same time on different systems don’t interfere with each other. It also
acts as a security guard making sure that unauthorized users are not
able to access the system.
There are four classifications of a computer operating system.
They are:
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
Multi-Processing: Supports running a program on more than
one CPU
Multi-Tasking: Allows more than one program to run
concurrently
Multi-Threading: 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.
Operating systems provide a software platform on top of which
other programs, called application programs, can run. The application
programs must be written to run on top of a particular operating
system.
Your choice of operating system, therefore, determines to a
great extent the applications you can run. For PCs, the most popular
operating systems are DOS, OS/2, and Windows, but others are
available, such as Linux.
In any device that has an operating system, there's usually a
way to make changes to how the device works. This is far from a
happy accident; one of the reasons operating systems are made out of
portable code rather than permanent physical circuits is so that they
can be changed or modified without having to scrap the whole device.
For a desktop computer user, this means you can add a new
security update, system patch, new application or often even a new
operating system entirely rather than junk your computer and start
again with a new one when you need to make a change.
As long as you understand how an operating system works and
know how to get at it, you can in many cases change some of the
ways it behaves. And, it's as true of your cell phone as it is of your
computer.
So, essentially, when you turn on your computer, the first
program is a set of instructions kept in the computer’s read only
memory. These instructions examine the system hardware to make
sure everything is functioning properly. This power-on self test check
the CPU, the memory, and the basic input/output systems (BIOS) for
errors and stores the result in a special memory location.
Once the test has successfully completed, the software loaded in
ROM (sometimes called the BIOS or firmware) will begin to activate
the computer's disk drives. In most modern computers, when the
computer activates the hard disk drive, it finds the first piece of the
operating system: the bootstrap loader.
The bootstrap loader is a small program that has a single
function: It loads the operating system into memory and allows it to
begin operation. In the most basic form, the bootstrap loader sets up
the small driver programs that interface with and control the various
hardware subsystems of the computer.
It sets up the divisions of memory that hold the operating
system, user information and applications. It establishes the data
structures that will hold the myriad signals, flags and semaphores that
are used to communicate within and between the subsystems and
applications of the computer. Then it turns control of the computer
over to the operating system.
It might be helpful for you to know the history of operating
systems.
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