Lecture 4. Operating System & Application Software

Transcription

1 Lecture 4 Operating System & Application Software

2 OS & Application Software OS & Application Software Application Software Operating System Driver Driver Hardware Introduction to Operating Systems

3 Linux Kernel Module Programming - 01 (If interested in Kernel programming, see the complete series) 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, LINUX, Windows Server 2008/2012

5 Device Drivers Device Drivers A device driver is a computer program which allows higher-level computer programs to interact with a hardware device. operating-system- Drivers are hardware-dependent and 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 Disk Operating System DOS IBM Introduced DOS (Disk Operating System) in 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.

7 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).

8 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 3.11 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.

9 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), Windows 7 (2010), Windows 8 (2012), Windows Server 2003 (2003), 2008 (2008) and 2012 (2012) are all available in 32 bit and 64 bit versions. The most recent client version of Windows is Windows 8; the most recent server version is Windows Server 2012.

10 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 First Version was created in Bell Labs in 1969 Various Proprietary UNIX OS like IBM AIX, SUN Solaris, SGI IRIX, HP HP-UX etc and public domain OS like various variants of LINUX and BSD are available Today most of the proprietary OS are also available free and for x86 platforms also

11 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 latest version is OS X v10.9 called Mavericks 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. Now they are planning to use ARM processors.

12 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.

13 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.

14 File System File System File system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. Most file systems make use of an underlying data storage device such as Hard Disks that offers access to an array of fixed-size blocks which is the smallest logical amount of disk space that can be allocated to hold a file. File systems typically have directories which associate file names with files, usually by connecting the file name to an index in a file allocation table of some sort, such as the FAT in a DOS file system, or an inode in a Unix-like file system.

15 File System File System File names are simple strings, and per-file Metadata is maintained which is the bookkeeping information, typically associated with each file within a file system. Metadata could contain file attributes such as file size, data and time of creation or modification of the file, owner of the file, access permissions etc.

16 File System Types of File System File system types can be classified into disk file systems, network file systems and flash file systems. A disk file system is a file system designed for the storage of files on a data storage device, most commonly a disk drive e.g. FAT, NTFS, ext3, ext4 etc. A network file system is a file system that acts as a client for a remote file access protocol, providing access to files on a server e.g. NFS, SMB etc. A flash file system is a file system designed for storing files on flash memory devices.

17 File System File System and OS Operating systems provide a file system, as a file system is an integral part of any modern operating system. Windows Operating system supports FAT and NTFS File Systems Linuxpopularlysupports ext3 and ext4 FileSystems Other flavors of Operating Systems may support other File Systems like UFS in many UNIX Operating Systems and HFS in MAC OS X. All Operating Systems provide a user interface like Command Line (CLI) or File Browser to access and manage File System information.

18 DOS/Windows File System FAT The File Allocation Table (FAT) file system was initially developed for DOS Operating System and was later used and supported by all versions of Microsoft Windows. It was an evolution of Microsoft's earlier operating system MS-DOS and was the predominant File System in Windows versions like 95, 98, ME etc. All the latest versions of Windows still support FAT file system although it may notbe popular. FAT had various versions like FAT12, FAT16 and FAT32. Successive versions of FAT were named after the number of bits in the table: 12, 16 and 32.

19 Windows File System NTFS NTFS or the NT File System was introduced with the Windows NT operating system. NTFS allows ACL-based permission control which was the most important feature missing in FAT File System. Later versions of Windows like Windows 2000, Windows XP Windows 8, Windows Server , Windows Server 2008 also use NTFS. NTFS has several improvements over FAT such as security access control lists (ACL) and file system journaling.

20 Linux File System File System in Linux Linux supports many different file systems, but common choices for the system disk include the ext family (such as ext3 and ext4), XFS, JFS and ReiserFS. The ext3/ext4 or third/fourth extended file system is a journaled file system and is the default file system for many popular Linux distributions. It is an upgrade of its predecessor ext2 file system and among other things it has added the journaling feature. A journaling file system is a file system that logs changes to a journal (usually a circular log in a dedicated area) before committing them to the main file system. Such file systems are less likely to become corrupted in the event of power failure or system crash.

21 References References Operating Systems: Kernel: %29 Device Drivers: File Systems:

22 Assignment 4 Assignment 4 1. If you install Windows and Linux on the same machine, first Windows needs to be installed and then Linux. Find out the reason why you have to do like this. 2. List the device drivers installed in your Linux partition. 3. Write the kernel file name of your Linux partition. Can you find out the kernel version you are using? 4. For any file in Linux, find out the entry corresponding to it in inode table. Can you find out the actual physical location in the hard disk where the content of this file is written? 5. Linux kernel releases 2.4, 2.6 and 3.0 are considered as major releases, in terms of features they supported. Can you do a feature comparison between these major releases. 6. Compare NTFS and EXT4 File Systems. What are the key differences between them? 7. Write the directory structure under / in Linux. Also write the typical content/type of files that are kept in these directories.