Computer Operating Systems

Computer Operating Systems Huh?

Computer Operating Systems • This lesson will cover: • Different Systems for Different Needs • GUI versus Command line • Operating System overview • The Microsoft Windows Family • Windows XP • Computer File Systems …these topics are from Chapter 2...

Computer Operating Systems Operating systems (OS) manage the input and output of data and the interpretation of instructions. It is the operating system of a computer that allows all the hardware to communicate and provide the services that the user requests. An operating system is no more than a software application, but it is the most important software on any computer.

Different Systems for different needs Computers are just like any machine, different uses require different functions. The range of computers from mainframes to handheld devices, perform very different tasks and do so at various levels of competency. When we discuss Operating Systems for computers these factors are very important. Some systems, like UNIX or Linux, are very robust and secure, but they are also very difficult for the average user to understand and use effectively.

Different Systems for different needs Windows however, is not so finicky. It is also not very secure or stable (compared to a UNIX system), but it is easy to master. There lies its strength; it is the operating system of the masses, a compromise between functionality and usability.

GUI versus Command line Windows XP, like Windows 2000, Windows 98 and all the Windows that came before, uses a Graphical User Interface, or GUI. A GUI employs graphical representations of the file system and the intricate functions of the operating system to eliminate the need to learn complex commands. This makes learning to use the software easier, and therefore, more useful to more people.

GUI versus Command line Systems that do not incorporate a GUI generally accept commands from a command line. For example, you might enter a text command such as dir or ls to show the contents of a folder (or directory). Windows was originally developed as a Graphical User Interface for MS-DOS (Microsoft Disk Operating System) in an effort to shield the user from the command line and make DOS (Disk Operating System) more “user friendly”.

Using a Command Line Interface… After entering the command “ver” at the command prompt and pressing the enter key… The operating system name and version number are displayed… Then the prompt returns for the entry of another command… This is the command prompt that is accessible through Windows XP. It is a command line interface to the XP operating system.

Notice the difference… Two commands, “time” and “date”, are entered with primitive results…

Notice the difference… …when one click on the Windows XP taskbar gives you this.

A (very brief) overview of some Computer Operating Systems The following slides show screen captures of various operating systems in action. Though their internals differ, you will notice a similarity among the GUIs…

The Apple Lisa… Apple released the Lisa in 1983. It featured a 5-MHz CPU, 1MB RAM, a 12-inch Black and White monitor, dual 5.25-inch floppy drives, and a 5MB hard drive all for the low price of $10,000…

MS-DOS… time, displays the current system time and allows you to change it type /?, displays help for the type command… /? is the command to display help. type dos.txt, displays the contents of the file dos.txt which is on the C: drive (because the filename was issued without a path it looks in the current directory, C:). This is an example of the MS-DOS command line session. Three commands have been entered, time, type /?, and type dos.txt.

MS-DOS… This screen capture shows the MS-DOS program “edit”, which is not a command line application, but still is a native DOS program.

Windows, version 1.01 The earliest version of Windows were basically graphical interfaces to MS-DOS. Microsoft prefers the phrase “graphical operating environment”. Windows, version 1, was released in November 1985.

Windows, version 3.1 Windows, version 3.1 …still a graphical interface for MS-DOS, included more features and “native” application support.

OS/2 Although it is starting to show its age, OS/2 is still used by many large corporations in mission critical functions such as banking.

AtheOS AtheOS is a free desktop operating system. AtheOS currently runs on Intel, AMD and other compatible processors.

Linux (SuSE distribution) Linux, much the same as with UNIX systems, can be used with a GUI (here is shown the KDE desktop using XFree86) or from a command line.

Mac OS 8 Apple’s use and development of the Graphical User Interface, as shown here in a Mac OS 8 screen capture, shaped standards, which are still used today in many other systems from UNIX to Windows.

Mac OS X…or, OS 10 Mac OS X is a completely new operating system for the Macintosh. It is based on UNIX and runs many applications originally written for those systems.

LindowsOS LindowsOS is a Linux distribution that is setting itself up as the “bridge” to lead PC users from Microsoft’s Windows products.

GNOME Desktop for Windows GNOME is a free, open source desktop that runs on many operating systems, including Windows. Here you see the GIMP, a free graphics program like Photoshop, running on Windows desktop.

The Microsoft Windows Family Microsoft Windows began as an idea for a friendlier interface for the current Disk Operating System (DOS). In fact, the first development by the company in this area was called the Interface Manager. This was in September of 1981, the same year Bill Gates said, “640 K ought to be enough for anybody” (referring to a PC’s memory requirements).

The Microsoft Windows Family Windows’ development has been characterized by missteps and “borrowed” ideas…by the way where did Microsoft Bob come from…or better yet, where do he go so fast?

The Microsoft Windows Family If you are interested in dates and timelines go to this web site: http://www.computerhope.com/history/windows.htm More details on the evolution of Microsoft Windows (with screen captures) can be found at: http://toastytech.com/guis/ http://members.fortunecity.com/pcmuseum/windows.htm http://inventors.about.com/library/weekly/aa080499.htm

File Systems – How Computers Manage Data This subject may seem a bit technical and even unnecessary for the “average” PC user, but knowing how your file system works can allow you to: • Share your files with other users. • Hide your files from other users. • Save and protect your data from loss. • Move your files or take them with you when you are not using your “home” PC. • Organize your data (files) in a way that makes sense to you and suits your needs. • Make your Operating System work for you…

Computer File Systems A computer’s file systemis its method of organizing the data stored on its Secondary or Mass storage devices, such as hard disks and CD-ROMs. Generally, the file system is dictated by the operating system, each having its own preferred type. Some operating systems, such as Windows XP, can use more than one file system as its primary file system.

Windows XP File Systems • Windows XP can use three types of file systems; these are considered native Windows file systems: • NTFS (New Technology File System) - this is the standard XP file system, it provides the most efficient storage and the best data security. • FAT32 (File Allocation Table 32 bit) - This system is compatible with Windows applications written for Windows 95 and later versions of Windows. • FAT (File Allocation Table) - This 16 bit file system was created for DOS and suffers from poor security, inefficient storage and a filename limit of 11 characters (8 characters with a 3 character file extension). Many older programs still require this file system.

Computer File Systems Computers need to manage data in a way that makes user access and data management as easy as possible. Most operating systems use a Hierarchical file system to organize and mange data. To use a system like this, your computer needs to define the levels of the hierarchy. This is done by making the basic data structure a file.

Computer File Systems Files are organized into foldersor directories, which are placed in a drive.

Hierarchical File Systems Windows XP uses a hierarchical file system. The figure to the right shows a file system tree. The top level is called the root. Every drive has a root. Below the root are located all the folders and files on that drive. Some files exist in the root of the drive; the others must be situated within a folder. The subordinate folders may contain only files, or only folders or both.

Windows XP File System Windows XP uses the same analogy of a tree and the hierarchy to display the file system to you. You can see from the view of XP’s My Computer folder on the following slide. That file system tree closely resembles the generic tree previously shown. Windows XP does, however, make some important changes to this view for your ease of use. The Desktop folder is always shown as the top-level folder with the actual drives, folders and files placed in the My Computer branch of the tree. Remember, the Desktop is NOT the root of a Windows XP file system!

Windows XP File System The Windows XP file system as represented by My Computer… The Desktop folder The My Computer folder is the place where the file system tree is located… The A drive (floppy) The C drive, the root folder Zip drive The CD-ROM drive Network drives

Windows XP File System • The three basic elements of the Windows XP file system are: • File– this is the smallest element of a file system.. There are two types of files: data files and executable files. A data file stores only data and is used by executable files (or programs) as a source of input or output. • Folder or Directory– a folder isan object used to organize and store files. Folders can be divided into sub folders to further aid in organization. Some operating systems use the term “directory” instead of folder. • Drive or Partition – a drive is either the whole or a portion of a mass storage device such as a hard disk. When you divide the hard disk into more than one drive, you are partitioning it. Drives are given letter names from C and can go to Z. When a PC uses tape drives and other removable drives, such as Zip and Jazz drives, they, too, may appear with a drive letter. Floppy drive letters are always either A or B. Any drive can also have a label which is like a nickname.

Windows XP File System Some of the common drive types used by Windows XP and their associated icons are: Hard disk or a partition of a physical hard drive Floppy disk drive CD-ROM or DVD drive Removable media drive, such as a Zip drive Network drive

File Paths… Every file has a path. A file’s path is simply the complete address for that file within the file hierarchy. For example a file that exists: On the C drive… In the Program Files folder, In the Windows NT sub-folder, In the Accessories sub-folder, Named wordpad.exe would have the following path: C:\Program Files\WindowsNT\Accessories\wordpad.exe

The path: C:\Program Files\WindowsNT\Accessories\wordpad.exe, as represented in Windows Explorer’s “address” box…

Computer Operating Systems