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Lecture 3
Operating System
&
Application Software
OS & Application Software
OS & Application Software
Application
Software
Operating
System
Driver
Driver
Hardware
Software Component
Software Component
Applications
Operating System
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API: application program interface
File management
I/O Drivers
Network Module
Kernel
• Memory management
• Resource scheduling
• Program communication
• Security
Operating System
What is an Operating System
Operating System handles
Process & Task Management
Interrupt & Exception Handling
Memory Addressing & Management
Process Scheduling & Synchronization
File System
Examples of Operating Systems
Single-user, Single-task: PalmOS
Single-user, Multi-task: MS Windows and MacOS
Multi-user, Multi-task: UNIX, Windows Server
2003/2008
Device Drivers
Device Drivers
A device driver is a computer program which allows
higher-level computer programs to interact with a
hardware device.
Drivers are hardware-dependent and operating-systemspecific.
They usually provide the interrupt handling required for
any necessary asynchronous time-dependent hardware
interface.
A device driver simplifies programming by acting as an
abstraction layer between a hardware device and the
operating systems that use it.
Drivers are usually written by the companies that
develop the hardware or by others for free operating
systems like Linux.
QUESTIONS?
Disk Operating System
DOS
IBM Introduced DOS (Disk Operating System) in
1981. Later many versions like MS-DOS (1982) by
Microsoft were introduced.
Text based OS
All DOS-type operating systems run on machines
with the Intel x86 or compatible CPUs, mainly the
IBM PC and compatibles.
DOS is a single-user, single-task operating system
with basic kernel functions that are non-reentrant:
only one program at a time can use them.
Disk Operating System
DOS
DOS consists of two parts, the kernel and the
command.com which is the command interface.
The DOS kernel provides various functions for
programs, like displaying characters on-screen,
reading a character from the keyboard, accessing
disk files and memory etc.
Command.com provides the shell or the user and
system commands
The new Windows versions provide emulated DOS
command interface (cmd).
Windows Operating System
Windows Operating System
Microsoft Windows has a significant majority of
market share in the desktop and notebook computer
markets
Microsoft first introduced an operating environment
named Windows in November 1985 as an add-on to
MS-DOS in response to the growing interest in
graphical user interfaces (GUIs). It was a 16 Bit OS
running on top of DOS providing Multitasking and
GUI
Windows 3.0 (1990) and Windows Workgroup 3.11
(1992) improved the design and were 16/32 Bit OS.
Windows 3.1 had Internet Explorer browser as a part
of the OS.
Later came Windows 95 (1995), Windows 98 (1998)
and Windows ME (2000) which were 32 Bit OS and
used FAT File System and supported DOS also.
Windows Operating System
Windows Operating System
NTFS was introduced in 1993 as the file system for
Windows NT server and it was later adopted as
default File system for all later releases of Windows
client and server OS.
Windows NT 4.0 (1996) was a popular server OS
which was later replaced by Windows 2000 (2000).
NT was the true Multi-User and Multi-Tasking OS
based on NTFS File System.
Windows XP (2001), Vista (2006), 2003 (2003) and
2008 (2008)are all available in 32 bit and 64 bit
versions.
The most recent client version of Windows is
Windows Vista; the most recent server version is
Windows Server 2008.
QUESTIONS?
UNIX Operating System
UNIX Operating System
Servers generally run on Linux or other Unix-like
systems
UNIX was designed as a Multi-User and MultiTasking OS
Various Proprietary UNIX OS like IBM AIX, SUN
Solaris, SGI IRIX, HP HP-UX etc and public domain
OS like various variants of LINUX are available.
Today most of the proprietary OS are also available
free and for x86 platforms also.
Apple OS
Apple Operating System
Apple introduced the Macintosh OS (Mac OS) in
1984 which had a graphical user interface
Various versions have come since then and the
current version is Mac OS X v10.5 “Leopard”
Apple OS was based on Unix (much like BSD Unix)
and so it has always been more robust and faster
than windows.
The processor used in Apple computers was
PowerPC until 2006 when they switched over to Intel
platform.
Multi OS System
Multiple Operating System
Multi-Boot system
Combination of Windows and Linux is the most
popular
Generally multi-boot system boots into any one OS
at a time.
Virtualization software like VMware can be used to
run multiple instances of OS simultaneously on the
same physical machine.
Boot Loader
Boot Loader
Booting is a process that starts operating systems
when the user turns on a computer system.
A boot sequence is the initial set of operations that
the computer performs when it is switched on.
The bootloader typically loads the main operating
system for the computer.
The bootloader may be multistage
In Desktop Computers, the boot process involve
running of system BIOS followed by the second
stage bootloader like GRUB, BOOTMGR, LILO or
NTLDR which is located in the boot sector of the
boot device or the hard disk.
QUESTIONS?
Thank You