Transcript Operating Systems

Operating Systems
What is an Operating System?
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Computer requires two types of
software:
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Application software
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Operating systems software
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Used to control and monitor the running
of application programs
Allow the users to interact with the
computer’s hardware & software
Operating System
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Typically consists of a number of
programs (System Software)
Usually bundled with the hardware
How it works?
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Each time you switch on your PC,
the operating systems kernel (the
part you need in memory at all
times) is copied from your hard disk
into memory.
What is the Kernel?
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Central component of an operating system
www.wikipedia.org
Responsible for servicing resource requests between applications
and hardware
A kernel has facilities to receive resource requests and grant
access to resources such as allocating space for a new file or
creating a network connection.
Kernels use a system call interface to handshake with
applications
What is it responsible for?
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Process management
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Memory management
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Device management
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System calls
www.wikipedia.org
Process management
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The kernel dictates which programs run and when they run
by creating various processes and threads within those
processes.
A process is nothing more than some memory allocated to a
running program, and the threads are individual streams of
execution within a process.
The kernel orchestrates various processes and their threads
so that multiple programs can run simultaneously and
transparently on the same machine.
http://e-articles.info/e/a/title/What-Is-the-Kernel/
Memory Management
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The kernel allocates memory to running programs, and
frees that memory when it is no longer required.
This memory control is implemented in the kernel's virtual
memory management function, which utilises physical
RAM and hard drive space to store information for running
processes
http://e-articles.info/e/a/title/What-Is-theKernel/
Device management
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When various hardware components of the machine need
attention (e.g., a packet arriving on the network interface) or
a program encounters an usual event (e.g., division by zero),
the kernel is responsible for determining how to handle the
resulting interrupts.
By taking care of the interrupt itself using kernel code or
sending information to a particular process to deal with it, the
kernel keeps the system operating smoothly.
Manages Plug and Play in Windows
http://e-articles.info/e/a/title/What-Is-theKernel/
System calls
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A system call is how a program
requests a service from an
operating system's kernel that it
does not normally have permission
to run. System calls provide the
interface between a process and the
operating system.
www.wikipedia.org
Some of the functions of an Operating
System
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Interface (File Management)
File System
Task Management
Machine and peripheral
management
Device Drivers
Interface
A user interface is the system by
which people (users) interact with a
machine. The user interface
includes hardware (physical) and
software (logical) components. User
interfaces exist for various systems,
and provide a means of input and
output.
Types of Interface
Command Driven Interface
Graphical User Interface GUI
File System
A file system (often also written as
filesystem) is a method of storing
and organising computer files and
the data they contain to make it
easy to find and access them.
en.wikipedia.org/wiki/File_system
FAT – File Allocation Table
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A table that the operating system uses to
locate files on a disk. Due to
fragmentation, a file may be divided into
many sections that are scattered around
the disk. The FAT keeps track of all these
pieces.
FAT file systems are commonly found on
floppy disks, flash memory cards, digital
cameras, and many other portable
devices because of their relative
simplicity.
en.wikipedia.org/wiki/File_system
FAT
http://www.pcguide.com/ref/hdd/file/partSizes-c.html
Worth a visit
MS DOS
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FAT12
FAT16
Newer versions of DOS can support
FAT32 however legacy DOS can not.
NTFS
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NTFS (New Technology File System) is
the standard file system of Windows NT,
including its later versions Windows 2000,
Windows XP, Windows Server 2003,
Windows Server 2008, Windows Vista,
and Windows 7.
NTFS supersedes the FAT file system as
the preferred file system for Microsoft’s
Windows operating systems.
en.wikipedia.org/wiki/File_system
NTFS
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When a file is created using NTFS, a
record about the file is created in a
special file, the Master File Table (MFT).
The record is used to locate a file's
possibly scattered clusters. NTFS tries to
find contiguous storage space that will
hold the entire file (all of its clusters).
Each file contains, along with its data
content, a description of its attributes (its
metadata).
NTFS
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It provides security by supporting access control and
ownership privileges, meaning you can set permission
for groups or individual users to access certain files.
NTFS supports compression of individual files and
folders which can be read and written to while they are
compressed.
NTFS is a recoverable file system, meaning it has the
ability to undo or redo operations that failed due to
such problems as system failure or power loss
Encryption - The NTFS file system can automatically
encrypt and decrypt file data as it is read and written
to the disk.
Windows
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Windows XP Professional supports
the FAT16, FAT32, and NTFS file
systems.
Task Management
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A multitasking operating system is
any type of system that is capable
of running more than one program
at a time.
Most modern operating systems are
configured to handle multiple
programs simultaneously.
Task Management
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With older examples of the multitasking operating
system, managing two or more tasks normally
involved switching system resources back and
forth between the two running processes.
The system would execute tasks for one, freeze
that program for a few seconds, and then execute
tasks for the other program. While this approach
did create a short time lag for the operator, this
lag was usually no more than a few seconds, and
still offered considerable more efficiency than the
older single-task operating system.
Task Management
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Single tasking
As the name implies, this operating
system is designed to manage the
computer so that one user can
effectively do one thing at a time.
Machine & Peripheral Management
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The Operating System talks to the devices in a computer system using
device drivers that are special programs designed to interact with the
physical devices of the system.
The device manager isolates the device drivers from the Kernel of the OS
and the user applications from the system’s hardware. It acts as an
interface between the device drivers and both the kernel and user
applications.
Interrupt
An interrupt is a signal that informs the processor that a particular device
wants its attention. The processor responds to the request, saves the
status of the current activity, executes the requested activity and on
completion, retrieves the saved activity and resumes the same. Interrupts
are of two types, Hardware Interrupts and Software Interrupts.
How does Windows manage it peripherals?
Drivers
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Device drivers are small files that act like an
interface between hardware in a computer system
and the operating system (OS).
Hardware requires device drivers so that the OS
can “see” the devices and handle them effectively
and efficiently.
Common components that require drivers include
keyboards, mice, controllers, graphics cards and
audio hardware.
Do some operating systems come with preinstalled drivers (OEM)?
Task
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Use DOS, try out some of the
commands.
Do the same activities within
Windows.
What was the difference?
Research and document the
functions and features of both
operating systems.