Introductory Computers

1
Introductory Computers

• Lesson 2
• Operating System Fundamentals

2
Operating Systems

• The operating system is what ties everything you
  do on the computer together.
• The operating system
• Is a platform that enables other programs to run
  on the computer.
• Translates input from devices such as the
  keyboard, the mouse, a scanner, etc.
• Sends output to devices such as a printer, the
  monitor, etc.
• Manages files and directories on the removable
  disks and hard drives connected to the computer.
• Provides tools for security, especially if the
  computer is part of a network.

3
Platforms

• There are currently three main platforms for
  running a computer
• Windows
• Macintosh
• Linux

4
Platforms Windows

• Microsoft Windows is arguably the most used
  operating system in the world (some estimate that
  between 80 to 90 of computers run Windows). It
  certainly is the easiest platform for which to
  find software. Windows runs on PC computer
  hardware, especially requiring an
  Intel-compatible processor (such as the ones made
  by manufacturers like Intel or AMD).
• Windows XP, the latest version of Windows, uses a
  graphical user interface (GUI) to manage files
  and run software.

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Platforms Macintosh

• Next in popularity to Windows, the Macintosh
  platform by Apple is the most common alternative
  to Windows. The Macintosh operating system
  requires different hardware than Windows, in
  particular the PowerPC processor (mostly
  manufactured by Motorola).
• The latest version of the Macintosh platform is
  called OSX. The Mac platform has long been
  favored by artists and designers for graphical
  and multimedia work.

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Platforms Linux

• Rapidly gaining ground in the platform popularity
  contest is the Linux platform. Part of its
  success lies in its roots in the Open Source
  software movement - there are many distributions
  of Linux available for free to download off the
  Internet. Linux offers a great amount of user
  control and configuration to the user, but also
  requires a greater amount of technical
  proficiency in order to install and configure it.
• The Linux operating systems can run on the same
  PC hardware as Windows. In fact, many users of
  Linux will often configure their computers to
  dual boot - where the user has the choice to run
  either Windows or Linux when they turn on the
  computer.

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Open Source

• Open Source where programmers make the source
  code for software free and publicly available for
  others to download and use, and relies on those
  users to share all improvements they make to the
  software with all other users.

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GUI

• Almost all computers provide a graphical user
  interface to make performing tasks on the
  computer much more intuitive. Each platform's GUI
  will be different, but every single one has
  certain elements in common.
• The pointer
• The mouse (or another pointing input device) can
  be used to navigate a pointer around the space on
  the computer screen. You use the pointer to
  manipulate the objects on the screen click them,
  select them, move them, or resize them (to name a
  few basic operations).
• Desktop
• Just like the space on a desk where you can
  arrange all your folders, documents, and tools,
  so does the GUI have a an area of the screen
  (usually, the whole screen) where the GUI
  elements can be stored and arranged.

9
GUI

• Icons
• An icon is a graphical image that represents the
  files, programs, folders, and all other data and
  elements that can exist on your computer. You
  manipulate an element on the computer by
  manipulating its icon in the GUI. For instance,
  double-clicking a program icon to launch it, or
  dragging a file icon into a folder icon to move
  the data.
• Windows
• A window represents a program, or a space on your
  desktop where activity can take place (like
  running a program). You can move windows around
  the desktop in any order, and resize them to fit
  any size you might need.
• Menus or toolbars
• Most windows will have a series of menus through
  which you can navigate to display the names of
  commands that can be carried out in that window.
  A toolbar is similar, except graphical icons
  represent the commands instead of text names.

10
GUI

• Three-dimensional window depth
• In addition to being resized to take up as much
  two-dimensional space as you want on your
  desktop, windows can also be stacked into
  three-dimensional layers, with one covering
  another. Like the desktop analogy, this is
  analogous to papers or folders being stacks one
  on top of the other on a real desktop.

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Virtual Desks / Filing Cabinets

• Virtual Desks and Filing Cabinets
• Because the personal computer has always been
  designed with business in mind, file management
  is based on the "desk" analogy-imagine that the
  computer is like a desk at which you work.

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Files

• The data file is the basic building block in
  which you organize information on the computer.
• Like a paper file, a data file can hold text or
  images, but it can really hold any information
  that a program writes to it.
• The general rule is that a file created by a
  program always needs that same program to read
  and edit it again.
• There are exceptions to this rule, though, since
  many programs have functionality to open files
  created by other software. For example, the
  Microsoft Word (a word processor), can read not
  only files created by Word, but also text files,
  files created by certain versions of other word
  processors, certain types of image files, and
  HTML files.

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File Extensions in Windows

• To distinguish between the different types of
  files, Windows adds a certain code to the end of
  a file name. Traditionally, this code is three
  characters long (though it can be longer), and
  the letters offer some description as to the type
  of file. For example, a file created by Microsoft
  Word ends with .doc, indicating that it is a Word
  document.
• Every program is likely to save its own
  proprietary file format, but there are also some
  universal formats that have a greater likelihood
  of being read by many different applications. The
  following table introduces a few of these file
  types along with their extension.

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File Extensions in Windows
15
File Extensions in Windows

• In addition to file extensions, most operating
  systems also display the file type by associating
  a certain icon with that type of file. That way,
  even if you can't immediately see the file's
  name, you can tell what type of file it is.
• Each operating system has a certain number of
  icons for standard file types, and programs can
  also provide custom icons for files made by or
  used specifically with that program.

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Displaying File Extensions in XP

• In Windows XP, the file extensions are hidden by
  default. For more efficient file management, it's
  always best to have file extensions displayed.
  For example, sometimes a program will use the
  same icon for different types of files used by
  the program. Without knowing a file's extension,
  you will have no way of distinguishing between
  these different types of files.

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• To display the file extensions in Windows XP
• Press the Start button, and then click Control
  Panel icon.
• Select Tools Folder options from the menu bar.
• Click the View tab.
• Uncheck the "Hide extensions for known file
  types" option in the Advanced settings box.
• Click OK, and close the Control Panel.

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19
Folders

• If every file on the computer were stored in one
  place, it would soon take forever to browse
  through the contents of that place-a computer can
  easily have 10,000 files or more, even if it's
  never been used before.
• So, just like folders are places in which you can
  store paper files to keep them organized and easy
  find, data folders are divisions of a data
  storage device (like a hard disk) into which you
  can sort files.
• All storage devices have a "first" folder, known
  as the root directory. All folders created are
  subfolders of this root folder.

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File Management

• While the procedures for managing files differ
  from operating system to operating system, many
  of the concepts and commands behind the
  procedures are the same. These essential commands
  are examined on the following slides.

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Creating Files and Folders

• In order for a file to exist, it must be created,
  and thus saved to the disk. Normally, this is
  done in a program by saving the file currently
  being edited.
• It is also possible in Windows to right-click a
  folder anywhere and select an option to create a
  new empty file.
• This is only possible for certain file types that
  have been programmed into the operating system
  (like text files), or when a specific program has
  made the command available to the operating
  system.

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23
File Naming

• While in theory you could name a file anything
  you like, there are certain conventions to be
  followed, as well as limitations.
• A file's name should easily identify its content.
  I.e., "Letter" is a pretty ambiguous file name,
  while "Letter to Mom (March 16)" is much more
  descriptive. A file name must have a file
  extension, to associate it with a particular
  program.
• Though, as described above, in default installs
  of some operating systems (like Windows XP),
  these extensions won't be immediately visible.
  File names in Windows XP cannot be longer than
  255 characters, and cannot contain the
  characters \ / ? " lt gt

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Save As

• The Save as command saves a new copy of the file
  currently being edited, but under a new name.
• This is very handy for creating several versions
  of a document, prior to making edits. Simply save
  the current state of the document, then select
  Save As, and save a new version in which to carry
  out your edits.
• If you don't like the way the edits are going,
  you can always go back to the file containing the
  version of the document prior to the edits.

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Copy

• Copy, paste, and cut are incredibly handy
  commands. Mostly used for file editing, they also
  can be used for managing files.
• When you copy a file, it is placed into a
  specific part of your computer's memory (called
  the Clipboard), and can then be pasted into any
  folder or drive that you can access from your
  computer. When you copy a file, the original file
  remains untouched.

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Paste

• When you paste, you create a new copy of whatever
  file is saved into the operating system's
  Clipboard memory. The pasted file will always
  carry the same name as the original file that was
  copied-unless it is pasted back into the same
  directory as the original. In that case, the new
  copy of the file will have its name modified
  slightly, to indicate it is a new copy.

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Cut / Move

• To cut a file is to copy it into the Clipboard,
  and then delete it from its current spot on a
  drive. You then can paste the file anywhere else
  you can access from your computer.
• The cut and paste combination is also known as
  moving a file, since all the file's data only
  exists in the new spot once it has been cut, and
  can no longer be found in the old.

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Rename

• As mentioned previously, naming files is a key
  part of file management. Another important part
  is the ability to change a file's name whenever
  you like.
• Reorganization is essential to managing files,
  and it is often very useful to rename certain
  files to help reorganize the way files or folders
  are laid out.

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Selecting Objects

• In order to carry out the file management tasks
  described previously, you need some way to
  indicate to the operating system which files are
  to be affected.

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Selecting Objects

• Using the pointer in the GUI, there are a couple
  of techniques for selecting files.
• The first is the click. Click once on a file, and
  it becomes highlighted. This means that it is
  selected, and the operating system is then
  waiting for a command from you (like "rename" or
  "delete") to apply to the selected object.

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Selecting Objects Lasso

• If you click at a point above or below a group of
  files, hold down the mouse button and start
  dragging the pointer, you will see a rectangular
  outline begin to grow between the point you first
  clicked and the pointer. This is called the
  lasso. Any icons "caught" in that lasso will be
  selected as soon as you release the mouse button.
  This is the easiest way to select large numbers
  of adjacent files in the same folder.

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Selecting non-adjacent objects

• By holding down the CTRL key while you lasso or
  click objects to select them, you can maintain
  the current selection and select more objects
  that are not adjacent.

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Deleting

• Just like a paper file can be thrown into the
  trash (or shredded, or recycled) to get rid of
  it, and to clear out space for more files, so too
  can data files on the computer be deleted to free
  up space for other files.
• There are many different ways to carry out the
  delete command, but by far the easiest is to
  select the files to be deleted, and drag them to
  the Recycle bin (called the Trash folder on
  non-Windows computers). If the Recycle Bin icon
  is not visible, you can also press the Delete key
  on the keyboard.

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The Trash folder/Recycle Bin

• Files that are in the Recycle Bin do still take
  up space on your computer, though. So every now
  and then you need to empty this special folder.
• Once the Recycle Bin has been emptied, the space
  taken up by the files is freed and they are truly
  gone.
• When a file is in the Recycle Bin, it cannot be
  opened by the operating system. The Recycling Bin
  is simply an intermediate place where all deleted
  files collect.
• That way, if you delete something and then decide
  in a few hours that you actually needed it, it is
  a very simple task to restore it from the Recycle
  Bin.

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Searching

• There can be times when even the sharpest user
  forgets where the file that he or she needs is
  located. That is when it is time to get the
  operating system to carry out a search for the
  file.
• A search for a file scans all storage devices
  connected to the computer and builds up a list of
  any files that match the criteria being searched
  for. These procedures are slightly different
  between Windows and Macintosh computers.

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Viewing File Information

• Knowing all the details about a file is the best
  way to know how to manage it. At any time, you
  can select a file and get the operating system to
  display all information about that file in a
  separate window.
• Displaying Files in Windows
• Right-Click on the File icon.
• Choose Properties.
• Displaying Files in Macintosh
• Click on File the icon.
• Press CommandI.

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Viewing Options

• The default file display in all operating systems
  is to show icons for all files in windows that
  browse the contents of folders. Most operating
  systems offer a number of commands to change the
  way that files are displayed (called changing the
  view), and to sort the way files are displayed
  within that view.
• Windows XP usually has five different views for
  every window (plus one more, depending on the
  predominant type of file being displayed).

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Sorting

• The default way to sort files is by name (A-Z or
  Z-A), but you don't have to stop there. Files can
  also be sorted in a window by type, size, date
  modified, or a number of other internal file
  parameters.
• For example, you can sort music files by artist,
  track number, or even the name of the album from
  which the file was taken.
• To add and remove sorting criteria in Windows XP
• Open a window with files to sort..
• Select View Choose Details.
• Check and uncheck the details by which you want
  to be able to sort files.
• Click OK when finished.
• Select View Arrange Icons by and select the
  detail by which to organize the files in the
  current window.

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File Attributes

• In Windows, files have attributes, which indicate
  how the operating system is supposed to treat the
  file.

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Showing hidden files

• Open a window.
• Select Tools Folder Options.
• Click the View tab.
• Under the Hidden files and folders heading in the
  Advanced settings box, select the "Show hidden
  files and folders" option.
• Click OK.

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Good Practices

• File management isn't all about manipulating
  files. There is a certain amount of preventative
  maintenance you should perform on your computer,
  and especially your hard drive to ensure that the
  data is kept safe from loss. The three things you
  should practice regularly to keep your data safe
  are
• Backup
• Defragment
• Disk scans.

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Backup

• To back up files means to make a duplicate of the
  files somehow, so that if the original is lost,
  accidentally deleted, or otherwise destroyed, you
  can always restore it from a backup.
• In practice, though, there are many ways of
  carrying out a backup of files on your computer,
  from making a duplicate on a removable or fixed
  disk, to periodically copying all files from a
  certain area, to making an exact image of an
  entire hard drive at a certain moment.

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Defragmentation

• Unlike a piece of paper, where text is stored in
  words, line-by-line, data on a disk is saved in
  pieces on the surface of the disk, known as
  clusters. When a computer saves data to a disk,
  it writes the file to the next empty cluster
  along its path, even if the clusters are not
  adjacent. This allows for very fast saving of
  files, and usually, the disk in the hard drive is
  spinning fast enough that this has little effect
  on the time it takes to open the file.

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Defragmentation

• However, as more and more files become fragmented
  across the surface of a disk, the longer it takes
  to carry out commands that require getting data
  from the disk. This can cause problems when
  launching software (because a program will often
  access many different files as it loads up), and
  when editing a fragmented file on an already
  fragmented disk. Normally, time is the only issue
  and bad fragmentation just makes every operation
  on the computer take longer. But, fragmentation
  can occasionally cause programs to crash or even
  corrupt data.
• So to avoid problems due to fragmentation, it is
  recommended to run a defragmentation utility on
  your computer regularly. Once a month is
  recommended as a minimum, and once a week is
  probably best.

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Scanning a Disk for Errors

• No hard drive will last forever. The wear and
  tear of regular use can eventually cause errors
  on the disk, either mistakes in the way data was
  saved or actual physical errors on the surface of
  the disk. For this reason, you should carry out a
  full surface scan on your hard drives about once
  a month.
• Windows XP, for example, will usually run a basic
  scan of the disk's file system for errors
  automatically after a crash, but the surface scan
  is not carried out automatically, and there are
  some types of disk surface errors that won't show
  up in the basic file system disk scan.