Catholic University College of Ghana Fiapre-Sunyani

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Catholic University College of GhanaFiapre-Sunyan
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System Software Input Devices

• INFORMATION TECHNOLOGY I

Audrey Asante, Faculty of ICST
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SYSTEM SOFTWARE

• It enables the application software to interact
  with the computer and helps the computer manage
  its internal and external resources.
• There are four basic types of system software
• Operating systems
• Utility programs
• Language translators
• Device drivers

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Components of System Software

• Operating systems are programs that operate your
  microcomputer. They coordinate computer
  resources, provide an interface between users and
  the computer, and run applications.
• Utilities, also known as service programs,
  perform specific tasks related to managing
  computer resources or files. They include
  programs to help users identify hardware
  problems, locate lost files, and back up data.
• Device drivers are specialized programs designed
  to allow particular input or output devices to
  communicate with the rest of the computer system.
• Language translators convert the programming
  instructions written by programmers into a
  language that computers understand and process.

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Functions of the Operating System

• Booting
• Managing storage media
• User interface
• Managing computer resources
• Managing files
• Managing tasks

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TYPES OF OS

• Real-time Operating System It is a multitasking
  operating system that aims at executing real-time
  applications. Real-time operating systems often
  use specialized scheduling algorithms so that
  they can achieve a deterministic nature of
  behavior. The main object of real-time operating
  systems is their quick and predictable response
  to events.

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Real Time OS

• They either have an event-driven or a
  time-sharing design. An event-driven system
  switches between tasks based on their priorities
  while time-sharing operating systems switch tasks
  based on clock interrupts.

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TYPES OF OS

• Multi-user and Single-user Operating Systems The
  operating systems of this type allow a multiple
  users to access a computer system concurrently.
  Time-sharing system can be classified as
  multi-user systems as they enable a multiple user
  access to a computer through the sharing of time.
  Single-user operating systems, as opposed to a
  multi-user operating system, are usable by a
  single user at a time.

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Multi-user and Single-user Operating Systems

• Being able to have multiple accounts on a Windows
  operating system does not make it a multi-user
  system. Rather, only the network administrator is
  the real user. But for a Unix-like operating
  system, it is possible for two users to login at
  a time and this capability of the OS makes it a
  multi-user operating system.

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TYPES OF OS

• Multi-tasking and Single-tasking Operating
  Systems When a single program is allowed to run
  at a time, the system is grouped under a
  single-tasking system, while in case the
  operating system allows the execution of multiple
  tasks at one time, it is classified as a
  multi-tasking operating system. Multi-tasking can
  be of two types namely, pre-emptive or
  co-operative.

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Multi-tasking and Single-tasking Operating Systems

• In pre-emptive multitasking, the operating system
  slices the CPU time and dedicates one slot to
  each of the programs. Unix-like operating systems
  such as Solaris and Linux support pre-emptive
  multitasking. Cooperative multitasking is
  achieved by relying on each process to give time
  to the other processes in a defined manner. MS
  Windows prior to Windows 95 used to support
  cooperative multitasking.

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TYPES OF OS

• Distributed Operating System An operating system
  that manages a group of independent computers and
  makes them appear to be a single computer is
  known as a distributed operating system. The
  development of networked computers that could be
  linked and communicate with each other, gave rise
  to distributed computing.

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Distributed Operating System

• Distributed computations are carried out on more
  than one machine. When computers in a group work
  in cooperation, they make a distributed system.

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TYPES OF OS

• Embedded System The operating systems designed
  for being used in embedded computer systems are
  known as embedded operating systems. They are
  designed to operate on small machines like PDAs
  with less autonomy. They are able to operate with
  a limited number of resources. They are very
  compact and extremely efficient by design.
  Windows CE, FreeBSD and Minix 3 are some examples
  of embedded operating systems.

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TYPES OF OS

• The operating systems thus contribute to the
  simplification of the human interaction with the
  computer hardware. They are responsible for
  linking application programs with the hardware,
  thus achieving an easy user access to the
  computers.

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UTILITIES

• There are hundreds of different utility programs.
  The five most essential utilities are
• Troubleshooting programs that recognize and
  correct problems, ideally before they become
  serious problems.
• Antivirus programs
• Uninstall programs
• Back up programs
• File compression programs

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UTILITY SUITES

• Like application software suites, utility suites
  combine several programs into one package.
  Example is Norton Utilities
• Norton Utilities is a collection of 17 separate
  troubleshooting utilities. These programs can be
  used to find and fix problems, improve system
  performance, prevent problems from occurring, and
  troubleshoot a variety of other problems.
• Norton Antivirus
• Norton cleansweep (guards for one to safely
  remove a program and files that are no longer
  needed. They can also protect existing files from
  damaging when new programs are installed. They
  make backups as well as clean hard disk.

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UTILITY SUITES

• Norton crashguard (intervenes to provide options
  for recovering current work)
• Norton web services ( notifies of available
  software updates to be automatically installed
  from the internet)

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Input Devices

• Keyboard
• Mouse

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Keyboard Layout

• QWERTY A standard computer keyboard is called a
  QWERTY keyboard because of the layout of its
  typing area. This keyboard is named after the
  first six  leftmost letters on the top alphabetic
  line of the keyboard.  A QWERTY keyboard might
  limit your typing speed.
• DVORAK A keyboard with an alternative layout was
  designed to improve typing speed. Called the
  Dvorak keyboard, this type of keyboard places the
  most frequently typed letters in the middle of
  the typing area.

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Types of Keyboard

• Wireless keyboards The most obvious difference
  between a wireless keyboard and a normal one is
  that the former uses infrared beams to transfer
  data to the computer as opposed to the latter,
  which uses a wire. As you type, a beam of data is
  sent from your keyboard to a receiver on the
  computer. The major advantage of this is that it
  eliminates one wire from the entangled web of
  wires from behind your desk. Many people also
  prefer to have a wireless mouse along with a
  wireless keyboard.
• It may not be possible for a corded keyboard to
  be kept in a particular place that is most
  comfortable to you. This is possible with a
  cordless keyboard, provided that it is placed in
  a position where the infrared beam is easily
  reachable by the computer. This distance can be
  different for different computers, so it makes
  sense to check the specifications before buying a
  wireless keyboard. This feature can be a problem
  for the user if an object or person happens to
  block the path of the infrared beam or the angle
  of the keyboard is not right.
• A wireless keyboard can be a valuable component
  is you are certain that the space between your
  keyboard and computer will remain free of
  physical obstructions. It will provide freedom
  and flexibility.

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Ergonomic keyboard

• The ergonomic keyboard has been designed to
  relieve some of the stress caused by repetitive
  typing and make for more comfortable typing.
  Prolonged usage of the keyboard can cause carpal
  tunnel syndrome or repetitive stress injury,
  which can be very painful. The specially
  designed, contoured ergonomic keyboards are
  helpful in such cases and even recommended by
  doctors.
• There is also a view that the traditional QWERTY
  layout is more stressful on the fingers and arms.
  Hence, the unconventional Dvorak keyboard layout
  has been designed for those who subscribe to this
  theory.
• While there are no design specifications for
  ergonomic keyboards, they generally have a
  contoured design for greater typing comfort, as
  opposed to the standard flat keyboard.

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Illuminated keyboards

• Much like mobile phone keyboards, these keyboards
  are backlit so that the keys are more visible
  even in poorly lit conditions.
• Often, when working at night, you may like to
  work only with the light of the monitor to
  prevent the glare of another light. An
  illuminated keyboard would be just the thing for
  you in such a situation. It is also great for
  multimedia presentations in boardrooms with dim
  lighting.

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Connection Types

• Wireless keyboard
• PS/2 keyboard
• USB keyboard

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Explanation of the Keys on a Windows QWERTY
Keyboard

•  Q  W  E  R  T  Y  "The name "QWERTY" for our
  computer keyboard comes from the first six
  letters in the top alphabet row (the one just
  below the numbers). It is also referred to as the
  "Universal" keyboard. It was the work of inventor
  C. L. Sholes, who put together the prototypes of
  the first commercial typewriter in a Milwaukee
  machine shop back in the 1860's.
• Esc Equivalent to clicking the Cancel button. In
  PowerPoint the Esc key will stop a running slide
  show. On a web page with animations, the Esc key
  will stop the animations. On a web page that is
  loading, the Esc key will stop the page from
  loading. The keyboard combination Ctrl Esc will
  open the Start Menu.
• F1 While working in an application, depressing
  this key will bring up the applications help
  menu. If there is no open application F1 will
  open Windows Help.

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• F2 Choose this key to rename a selected item or
  object.
• F3 Depressing this key will display the Find All
  Files dialog box.
• F4 Selects the Go To A Different Folder box and
  moves down the entries in the box (if the toolbar
  is active in Windows Explorer)
• F5 Refreshes the current window. In Internet
  Explorer, F5 will Refresh the web page.
• F6 Moves among panes in Windows Explorer.
• F10 Activates menu bar options. Use right and
  left arrows to select menus and down arrows to
  display pull down menus.
• F11 In Internet Explorer this key will allow you
  to toggle between full screen viewing mode and
  normal viewing mode.

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• Print Screen/SysRq Usually located at the upper
  right hand corner of your keyboard next to the
  Scroll Lock and Pause/Break keys. Often
  abbreviated PrtScr, the Print Screen key is a
  useful key supported on most PCs. In DOS,
  pressing the Print Screen key causes the computer
  to send whatever images and text are currently on
  the display screen to the printer. Some graphics
  programs and Windows, use the Print Screen key to
  obtain Screen Captures.
• Tab This key can be used to move forward through
  options in a dialog box. Ctrl Shift Tab can
  be used to move backward through the options.
  Ctrl Tab allows movement from one open window
  to the next in an application with more than one
  open window. Alt Tab displays a list of open
  application windows. Keeping Alt depressed and
  selecting Tab cycles through the list. Releasing
  selects the highlighted application window.

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• Caps Lock Locks the keyboard in "Capitals" mode
  (only applies to Alpha keys). The Caps Lock key
  should be used with caution. Using ALL CAPS is a
  usability no-no as many have difficulty scanning
  text that is ALL CAPS. Also, when sending email
  in all caps, this could be misconstrued as
  shouting at someone.
• Shift The obvious use of this key is to allow
  selection of capital letters when depressing the
  alphabet characters, or selecting the characters
  above other non-alpha keys. Depressing the Shift
  key while inserting a CD-ROM will bypass auto
  play. Shift Delete to permanently delete a
  selected item, bypasses the Recycle Bin.
• Control Key Ctrl Depressing the Ctrl key while
  clicking allows multiple selections. Holding the
  Ctrl key down and pressing other key combinations
  will initiate quite a few actions. Some of the
  more common ones are listed below.
• Ctrl A Select All items

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• Ctrl B Add or remove Bold formatting
• Ctrl C Copy, places the selected/highlighted
  copy on the clipboard.
• Ctrl C C Opens the clipboard.
• Ctrl F Opens the Find what dialog box. Great
  for finding references on a web page while using
  your favorite web browser.
• Ctrl H Replace, brings up the Find and Replace
  dialog box. Great for global find and replace
  routines while working in normal and html views
  in your favorite WYSIWYG editors like FrontPage.
  You can also use this to find and replace content
  within your Word Documents, Excel Spreadsheets,
  etc...
• Ctrl I Add or remove Italic formatting.
• Ctrl N Window, In Internet Explorer, opens a
  New Window. In Outlook, opens a New Mail Message.
  In most publishing programs like Word, opens a
  New Document.

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• Ctrl O Open, brings up a browse dialog and
  allows you to select a file to open.
• Ctrl P Print
• Ctrl S Save
• Ctrl U Add or remove Underline formatting.
• Ctrl V Paste, inserts the copy on the clipboard
  into the area where your flashing cursoris
  positioned or the area you have
  selected/highlighted.
• Ctrl W Close, will close the document currently
  open.
• Ctrl X Cut, removes the selected/highlighted
  copy and places it on the clipboard.
• Ctrl Y Redo last command. Many software
  programs offer multiple Redo's by pressing Ctrl
  Y Y Y...
• Ctrl Z Undo last command. Many software
  programs offer multiple Undo's by pressing Ctrl
  Z Z Z...
• Ctrl Esc Open the Start menu (or use the
  Windows Key if you have one).
• Ctrl Spell checker (pre WinXP).

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• Ctrl While dragging a file to copy the file.
• Ctrl Shift While dragging a file to create a
  shortcut.
• Ctrl Tab Allows movement (toggle) from one open
  window to the next in an application with more
  than one open window.
• Ctrl F4 Close a window in an application
  without closing the application.
• Ctrl F5 In Internet Explorer, Ctrl F5 will
  Refresh the web page bypassing cache (all images
  and external file references will be reloaded).
• Windows Key
• Windows Key On either side of the spacebar,
  outside the Alt key, is a key with the Windows
  logo. Holding the Windows key down and pressing
  another key will initiate quite a few actions.

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• Some of the more common are listed in the table
  below
• Displays the Start Menu.
• D Minimizes all windows and shows the Desktop.
• D Opens all windows and takes you right back to
  where you were.
• E Opens a new Explorer Window. Probably one of
  the hottest Windows keyboard shortcuts. This one
  gets a lot of hoorahs!
• F Displays the Find all files dialog box.
• L Lock your Windows XP computer. Logoff in
  Windows Pre-XP.
• M Minimizes all open windows.
• Shift M Restores all previously open windows
  to how they were before you Minimized them.
• R Displays the Run command.
• F1 Displays the Windows Help menu.
• Pause/Break Displays the Systems Properties
  dialog box.

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• Tab Cycle through the buttons on the Task Bar.
• Alt Alt Located on either side of the space bar.
  Holding the Alt key down and pressing another key
  will initiate various actions. Some of the more
  common ones are listed below
• Alt F4 Closes the current active window. If
  there is no active window this opens the Shut
  Down dialog box.
• Alt underlined letter in menu To carry out the
  corresponding command on the menu.
• Alt left/right arrows In a browser moves
  forward or back through the pages visited in a
  window.
• Alt Space Bar Displays the current window's
  system menu. This is the same as left clicking on
  the application icon at the top left of the
  window.
• Alt Enter Displays a selected items properties.
  This can also be done with Alt double-click.

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• Alt PrtScn Captures the top window of the
  active application.
• Alt Space Bar Displays the main window's system
  menu. This is the same as clicking on the
  application icon at the left end of the title
  bar.
• Alt Space Bar C After the system menu is
  displayed (see above), this combination will
  close a window. This works the same way as Alt
  F4 but requires less stretch.
• Alt - (hyphen) Displays the current window's
  system menu. This is the same as left clicking on
  the application icon at the top left of the
  window.
• Alt Tab Displays a list of open application
  windows. Keeping Alt depressed and selecting Tab
  cycles through the list. Releasing selects the
  highlighted application window.
• Alt  Ctrl The Application key has an image of a
  mouse pointer on a menu (between the Alt and Ctrl
  keys () to the right of your Space Bar).
  Depressing this key will display the selected
  item's shortcut window. This is the menu that is
  displayed by right-clicking.

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• Space Bar Insert a space between words. It is
  suggested that you utilize Tabs (or other
  formatting commands) to put distance between
  elements. Using the space bar to insert visual
  space works but would not be considered a best
  practice in page design. Double spaces between
  sentences are no longer required. This is a
  carryover from the days of fixed width fonts on a
  typewriter such as Courier, Orator, Prestige
  Elite, etc. Pressing the Space Bar while viewing
  a web page in Internet Explorer will scroll the
  page downwards. Shift Space Bar will scroll the
  page upwards.
• Enter Creates a new Paragraph ltpgt () or what is
  referred to as a Hard Return. In any dialog box a
  selected button or command can be selected by
  depressing this key. Selected buttons can be
  recognized by their darker (dotted) borders, or
  what is referred to as Focus.
• Shift Enter Creates a new Line Break ltbrgt () or
  what is referred to as a Soft Return.

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• Shift Arrow Shift Arrow Up, Down, Left or
  Right. Position your cursorat the beginning of
  the area you wish to highlight for copying. Now
  use the up, down, left or right arrow keys to
  select areas of content to be highlighted,
  copied, pasted, etc.
• Backspace While working with text, use this key
  to delete characters to the left of the insertion
  point.
• Home Depress and hold the Ctrl key as you select
  Home to go to the first line of a document.
• Page Up In a browser window use the Page Up key
  to move up one full screen on a web page.
• Delete While working with text, use this key to
  delete characters to the right of the insertion
  point. This key can also be used to delete
  selected files. If you use the keyboard
  combination Shift Delete the item is
  permanently deleted, bypassing the Recycle Bin.

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• End Depress and hold the Ctrl key as you select
  End to go to the last line of a document.
• Page Down In a browser window use the Page Down
  key to move down one full screen on a web page
• Up Arrow Navigate in a document to the line
  above. Hold the Ctrl key down as you press this
  key to move to the beginning of the second line
  above.
• Right Arrow Navigate in a document one character
  to the right. Hold the Ctrl key down as you press
  this key to move one word to the right.
• Down Arrow Navigate in a document to the line
  below. Hold the Ctrl key down as you press this
  key to move to the beginning of the second line
  below.
• Left Arrow Navigate in a document one character
  to the left. Hold the Ctrl key down as you press
  this key to move one word to the left.

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• Keypad Keys
• Num Lock If you want to use the numeric keypad on
  the right end of the keyboard to display numbers,
  the Num Lock key must be selected (usually a
  light above the Num Lock will indicate that it is
  on). If you want to use the keypad to navigate
  within a document, turn off Num Lock by pressing
  the key (the light will go off).
•    (Asterisk) In Windows Explorer this expands
  everything under the current selection. Caution
  do not try this with the C Drive icon selected.
•  -  (Minus Sign) In Windows Explorer this
  collapses the current selection.
•    (Plus Sign) In Windows Explorer this expands
  the current selection.

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FEATURES OF THE KEYBOARD

• Special purpose keys are used to enter, delete,
  and edit data and to execute commands.
• Function keys are used to execute commands
  specific to the software being used
• Macros are also called keyboard shortcuts. It is
  a single keystroke or command used to
  automatically issue a longer, predetermined
  series of keystrokes or commands.

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Mouse

• The mouse is a pointing device
• It allows for fine control of a Graphical User
  Interface.
• The mouse parts
• Left mouse button
• Right button
• Scroll wheel-for scrolling. This is an additional
  feature that has been added.

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Mouse

• Types of mouse
• Mechanical Mouse device This is a type of
  computer mouse that has a rubber or metal ball on
  its underside and it can roll in every
  direction.  There are sensors within the mouse,
  which are mechanical, detect the direction in
  which the ball is moving and moves the pointer on
  the screen in the same direction.  A mouse pad
  should be used under the mouse to run on.
• Optomechanical mouse devices This is the same
  as the mechanical mouse except that it uses
  optical sensors to the motion of the ball.  Your
  should use a mouse pad under the mouse to run on.
• Optical mouse device This type uses a laser for
  detecting the mouse's movement.  You don't need a
  mouse pad but you can use one made for optical
  mice.  Optical mice do not have any mechanical
  moving parts.  The optical mouse responds more
  quickly and precisely than the mechanical and
  optomechanical mice and now that they have been
  around awhile the price is pretty comparable.

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Here is how a computer mouse hooks up to the
computer

• Serial mouse  these ones connect directly to an
  RS-232C serial port or a PS/2port.  This is the
  simplest type of connection. it requires a free
  serial port on your PC.
• PS/2 mouse  connects to a PS/2 port.USB Mouse -
  This type of mouse has a USB connector and
  requires a free USB port.
• Cordless mouse  These are not physically
  connected to the computer.  They rely on infrared
  or radio waves to communicate with the computer. 
  Cordless are more expensive than both the serial
  and bus mouse.  The nice thing is that there is
  no cord to constrain or get in your way. this
  type of mouse utilises batteries for its power
  supply. Optical Mouse - An optical mouse
  utilises optical electronics to track the mouse's
  position and movement, they are preferred over
  standard mechanical mice as they tend to be more
  reliable and require less maintenance.

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Mouse

• Applications or directions of the mouse
• Single click
• Double click
• Triple click
• Drag and drop
• Roll over
• Selecting
• Pointing