Operating System Concepts, Terminology and ❖ The poor reliability of early operating systems
History is (in part) due to the lack of support for these
features.
Operating System Concepts
❖ Modern operating systems are those which
❖ An operating system to be the supporting
provide good support for these features.
software structure on which application
programs run. ❑ All of the UNIX variants, Linux, Mac OS
X and Windows NT, 2000 and XP
❑ This support structure includes the
provide support for these features.
facilities to manage the computer
system's resources and any utility ❖ As a result, these modern operating systems
programs needed to maintain and are more robust and reliable.
configure the operating system.
❖ UNIX systems refer to the Operating System’s
➢ The heart of system core component as the kernel.
administration is configuring
❖ A UNIX kernel handles the interaction with the
an operating system to create
system hardware.
an environment suitable for
the applications that the users ❖ The UNIX kernel is specific to a particular
require. computer or group of computers that share a
common hardware design.
❖ One can classify operating systems into two
broad groups, early and modern, based on an ❖ UNIX kernels are built around one of two
analysis of three key features: designs:
❑ Ability to share CPU resources ❑ a single, monolithic kernel or
between multiple programs.
❑ a micro-kernel.
❑ Methods employed to control access
to system storage. ❖ The monolithic design is older and uses a
single binary image to provide the resource
❑ Methods employed to protect system management and hardware interface
and application memory from functions of the core layer. Some examples of
corruption. the monolithic design are Linux and Solaris.
❖ Early operating systems provided poor support ❖ A micro-kernel design uses a very small task
for these three features. management component and a suite of
modules for all other resource management
❑ Running multiple programs, while
functions. Windows NT, Windows 2000,
possible, was done via a cooperative
Windows XP and Mac OS X are examples of
system which depended on each
micro-kernel designs.
application program to release the
CPU periodically to allow its peer ❖ The recent incarnations of Windows; NT, 2000,
processes to run. and XP share a similar layered construction
approach with UNIX.
❑ Protection of system storage was
limited. ❑ These recent versions of Windows are
based on a micro-kernel design using
❑ Critical system files and user files were
a small kernel layer and hardware
not protected from damage by user-
abstraction layer at their base.
level applications.
❑ The middle layer is made up of
❖ Finally, early operating systems did not
dynamically loaded libraries and
provide memory protection for individual
services.
processes or the operating system kernel, thus
allowing application “bugs” to result in ❑ The applications layer contains the
damage to the parts of the operating system familiar applications such as text
and applications loaded into memory.
History is (in part) due to the lack of support for these
features.
Operating System Concepts
❖ Modern operating systems are those which
❖ An operating system to be the supporting
provide good support for these features.
software structure on which application
programs run. ❑ All of the UNIX variants, Linux, Mac OS
X and Windows NT, 2000 and XP
❑ This support structure includes the
provide support for these features.
facilities to manage the computer
system's resources and any utility ❖ As a result, these modern operating systems
programs needed to maintain and are more robust and reliable.
configure the operating system.
❖ UNIX systems refer to the Operating System’s
➢ The heart of system core component as the kernel.
administration is configuring
❖ A UNIX kernel handles the interaction with the
an operating system to create
system hardware.
an environment suitable for
the applications that the users ❖ The UNIX kernel is specific to a particular
require. computer or group of computers that share a
common hardware design.
❖ One can classify operating systems into two
broad groups, early and modern, based on an ❖ UNIX kernels are built around one of two
analysis of three key features: designs:
❑ Ability to share CPU resources ❑ a single, monolithic kernel or
between multiple programs.
❑ a micro-kernel.
❑ Methods employed to control access
to system storage. ❖ The monolithic design is older and uses a
single binary image to provide the resource
❑ Methods employed to protect system management and hardware interface
and application memory from functions of the core layer. Some examples of
corruption. the monolithic design are Linux and Solaris.
❖ Early operating systems provided poor support ❖ A micro-kernel design uses a very small task
for these three features. management component and a suite of
modules for all other resource management
❑ Running multiple programs, while
functions. Windows NT, Windows 2000,
possible, was done via a cooperative
Windows XP and Mac OS X are examples of
system which depended on each
micro-kernel designs.
application program to release the
CPU periodically to allow its peer ❖ The recent incarnations of Windows; NT, 2000,
processes to run. and XP share a similar layered construction
approach with UNIX.
❑ Protection of system storage was
limited. ❑ These recent versions of Windows are
based on a micro-kernel design using
❑ Critical system files and user files were
a small kernel layer and hardware
not protected from damage by user-
abstraction layer at their base.
level applications.
❑ The middle layer is made up of
❖ Finally, early operating systems did not
dynamically loaded libraries and
provide memory protection for individual
services.
processes or the operating system kernel, thus
allowing application “bugs” to result in ❑ The applications layer contains the
damage to the parts of the operating system familiar applications such as text
and applications loaded into memory.
