The Computer Operating System

The Computer Operation System

This lesson will cover:

•Computer Operating Systems•GUI vs. Command line•The Microsoft Windows Family•The Concept of Windows•Windows XP•File Systems – How Computers Manage Data

…these topics are from Chapter 2…and then some.

Different Systems for Different Needs

• Different computers, different tasks and various level of competency i.e. Mainframe & Micro PC.

• Different Operating Systems, different functionality and usability.– UNIX or Linux – very robust and secure, however

very difficult for the average user to understand and use effectively. So usually used on network servers and engineering or programming workstations.

– Windows – not so finicky. Neither very secure nor stable compared to UNIX, but very easy to master. A compromise between functionality and usability.

GUI Vs. Command Line

Windows XP, like Windows 98 is a Graphical UserInterface, or GUI. It uses graphical representations of theunderlying complexities of the operating system to eliminate the need to learn complex commands. This makes using the software easier and more efficient.

Most modern operating systems have GUIs, such as the MacOS, Unix and Linux. Windows was originally developed as an interface for MS-DOS.

Notice the difference…

Two commands, “time” and “date”, were entered withprimitive results…

Notice the difference…

…when one click on the taskbar gives you this.

UNIX Operating System

• One of the first multi-user, multi-tasking operation systems

• Very robust and stable• Provides built in networking capabilities.• Known for its cryptic commands.• Many version of UNIX developed by

different sources such as Solaris, System V and SCO UNIX.

Linux Operating System

• Linux is a free ‘Unix-like’ operating system.

• Many of the same features of UNIX

• Available for many operating platforms.

OS/2

• Is a 32-bit multitasking operating system produced by IBM.

• Used by many large corporations in mission critical functions such as banking, ATM etc.

• Co-developed by IBM and Microsoft to replace DOS (Disk Operating System) in late 1980s.

Windows XP

• Is the latest version of Microsoft Windows family.• Two distinct versions of this OS for use on desktop PCs

i.e. XP Home Edition and XP professional and there are other versions for use as network servers.

• Is actually descendent of the Windows NT family rather than the windows 9x family.

• Difference between Home Edition & Professional version:– Advanced networking features for domain-based networks– Remote Access capabilities– Encrypting File System (EFS)– Support for multiple-processors– Support for multiple languages

File Systems – How Computers Manage Data

To understand Window’s use of files and folders, you need to know just a small bit about how a computer stores information. Computers store data which are pieces of information.

A computer’s file system is 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 type i.e. Windows XP can use more than one file system (Discussed in detail in later chapters)

File Systems – How Computer Manages Data

• The three basic elements of the Windows XP file system are:– File– Folder or Directory– Drive or Partition

File•A file is a collection of data. It is the smallest element of a file system and is a collection of bits and bytes to represent information in the form of text, image etc.•Basic types of files:

–Data files - stores only data and used by executable files as a source of input or output and Executable files.–Executable files - performs operations under OS, i.e. Applications.

•Examples of common file types used by Windows and Windows based programs are:

• Program – a program file is one that can be executed or “run”.• Text – this is the most basic form of text file, it is sometimes called a “plain” or “ASCII” text file.• System configuration - this type of file can be of several types such as an .ini, .sys or .dat file they store information that the system (or a program) needs to have readily available to function properly.• Compressed – a file of this type has been compressed by a program to reduce its size as a space saving measure.• TrueType font file – the standard Windows font type is stored in this kind of file.• Formatted text document – a document formatted by a word processor.

Folders and Drive/Partition

•A folder is a collection of files. Folders are used to organize the file system of a Windows based PC. The analogy of files and folders on a PC and files and folders in a file cabinet in an office is the easiest way to explain this relationship.

•A drive can be any mass storage device such as a hard drive, a cd-rom drive, zip drive, or a floppy drive. Some types of drives used by Windows are:

• CD-ROM or DVD drive

• Hard drive or a partition of a physical drive

• Floppy disk drive

• Removable media drive, such as a Zip drive

• Network drive

Relationship of Files to Folders to Drives:

On a Windows PC files are stored in folders on a drive…

Har d D r iv eP ar tit io n

F o ld erF ile

R elatio ns hip o f F iles to F o ld ers to D rives

A drive can actually be a part of a physical drive. This is called a drive partition. So one hard disk can have several drives labeled as letters from C to Z. The C: drive is always the first hard drive.

A hierarchical File Tree

Windows XP uses a hierarchical or TREE file system….

…such an arrangement uses directories, or folders, to organize the data files. The diagram to the left shows how this system, called a “tree”, is structured. The top level is called the root directory or simply the “root”. This directory contains all the files and folders below it. The subordinate folders may contain only files, or only folders or both. This is how the Windows Explorer presents the file system. “My Computer” in XP is such a root.

A file s ys tem "T ree"

R o o t le ve l

XP’s “My computer” folder contains the file system tree that closely resembles the generic tree seen before.

The A drive (floppy)

The C drive

The My Computer folder is the place where the file system tree is located…

The CD-ROM drive

The Desktop folder

Zip drive

Network drive

A hierarchical File Tree – File Path

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 driveIn the Program Files folder,In the Windows NT sub-folder,In the Accessories sub-folder,Named wordpad.exewould have the following path: C:\Program Files\

Windows NT\Accessories\wordpad.exe

Files and Folders

As stated before files store data in different ways. The difference can be like a text file versus program code, or an Word document and a WordPerfect document. The first two point out a difference in the actual data, the second pair a difference in “formatting”.

Many times a file’s content can be known by the file extension, that is the trailing letters of the filename after the “.” For example a file named opera.exe is an executable file (which is another name for a program file). The following slide lists several file types and their respective extensions.

Files and Folders

File Extension ApplicationEXE, COM Executable file

ZIP Compressed file using “Zip” compression

INI Configuration files, many programs use them, too

TXT ASCII text file, sometimes called “plain text”

DOC Microsoft Word file

XLS Microsoft Excel file

PPT, PPS Microsoft PowerPoint file

MDB Microsoft Access database file

GIF, JPG, BMP, PNG Image files

HTM, HTML HyperText Markup Language file

PDF Adobe Acrobat Portable Document Format