Chapter 1: Basic Operating System Concepts

The Concept Of The Operating System, Its
Purpose, And Function
The Concept of An Operating System
The main idea and start of our modern day operating systems was the need
to create ISG including them in the use of computer systems (By
computer cybernetic system,  we mean a set of hardware and software). The
computer cybernetic system initially developed for liability solutions and
practical problems of users. Because it was difficult to do this with
hardware alone, applications were created. These programs required general
operations of hardware management, distribution of hardware from
resources, and the like. These operations are grouped under a separate layer
of software, which is known as the operating system.
Further, the capabilities of operating systems went far beyond the basic set
of operations required by applications, but the intermediate position of such
systems between applications and hardware remained unchanged .
Purpose Of The Operating System
Operating systems provide us with a score of cybernetic system, and
secondly, efficiency and reliability of its work. The first function is
characteristic of the OS as an extended machine, the second - the OS as a
distributor of hardware resources.
Operating System As An Extended Machine
Using the operating system, the application programmer (and through his
programs and the user) should have the impression that they are working
with an advanced machine. The hardware is not well adapted for direct use
in applications. For example, if you consider working with I / O devices at
the command level of the respective controllers, you can see that the set of
such commands is limited, and for many devices - primitive. The operating
system hides such a hardware interface but instead offers the
programmer an application programming interface that uses higher-level
concepts (called abstractions).

For example, when working with a disk, a typical abstraction is a file. it is
easier to work with files than directly with a disk controller (no need to
consider moving the drive heads, starting and stopping the motor, etc.), as a
result, the programmer can focus on the essence of his application. The
operating system is responsible for interacting with the disk controller .
Abstraction highlighting makes it easy for OS and application code to
change when migrating to new hardware. For example, if you install a new
type of disk device on your computer (provided that it is supported by the
OS), all its features will be taken into account at the OS level, and
applications will continue to use the files as before. This characteristic of
the system is called hardware independence.  OS can be said to provide a
hardware-independent environment for executing applications.

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