Lecture 3

1. Lecture 3 Operating System & Application Software

2. OS & Application Software OS & Application Software Application Software Operating System Driver Driver Hardware

3. Software Component Software Component • Applications • Operating System • API: application program interface • File management • I/O Drivers • Network Module • Kernel • Memory management • Resource scheduling • Program communication • Security

4. 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

5. 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-system-specific. • 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.

6. QUESTIONS?

7. 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.

8. 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).

9. 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.

10. 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.

11. QUESTIONS?

12. UNIX Operating System UNIX Operating System • Servers generally run on Linux or other Unix-like systems • UNIX was designed as a Multi-User and Multi-Tasking 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.

13. 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.

14. 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.

15. 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.

16. QUESTIONS? Thank You