e s s e n t ia l c o n c e p t s
le s s o n 2
Interacting with
the Computer
This lesson includes the following sections:
The Keyboard
The Mouse and Its Variants
Alternative Methods of Input
Sound Systems
The Keyboard
A standard computer keyboard has about 100 keys
Most keyboards have keys arranged in five groups
1. Alphanumeric keys
2. Numeric keypad
3. Function keys
4. Modifier keys
5. Cursor-movement keys
* * * * *
ENTER Invalid Password
The Mouse and Its Variants
• Using a Mouse
• Variations of the
The Mouse and Its Variants Variations of the Mouse
The mouse is a pointing device. You use it to move a graphical
pointer on the screen and to issue commands without using the
keyboard. Using the mouse involves five techniques.
1. Pointing: Move the mouse to move the on-screen pointer.
2. Clicking: Press and release the left mouse button
3. Double-clicking: Press and release the left mouse
button twice.
4. Dragging: Hold down the left mouse button as you
move the pointer.
5. Right-clicking: Press and release the right mouse button.
Variants of the Mouse Trackballs
• A trackball is like a mouse turned upside-down. Use
your thumb to move the exposed ball and your fingers
to press the buttons.
• A trackpad is a touch-sensitive pad that provides the
same functionality as a mouse. To use a trackpad, you
glide your finger across the surface.
• An integrated pointing device is a small joystick built
into the keyboard. To use an integrated pointing device,
you move the joystick.
Many styles of trackballs are available
Alternative Methods of Input
Devices for the Hand
Optical Input Devices
Audio-Visual (Multimedia) Input Devices
Alternative Methods of Input Devices for the Hand
With a pen-based system, you use an electronic pen
to write directly on the screen and choose commands.
Pens are common input devices for handheld
computers, like PDAs.
Touch-screen systems accept input directly through
the monitor by detecting the touch of a finger.
Touch-screens are useful for selecting options from
The two primary types of game controllers are
joysticks and game pads. Game pads usually provide
controls for each hand. Joysticks are popular for
flight simulator and driving games..
The user can point, tap,
draw and write on the
computer’s screen with a
Alternative Input Devices Optical Input Devices
Bar code readers can read bar codes—patterns of
printed bars. The reader emits light, which reflects
off the bar code and into a detector in the reader.
The detector translates the code into numbers.
Image scanners digitize printed images for storage
and manipulation in a computer. Optical character
recognition (OCR) software translates scanned text
into editable electronic documents.
Bar code readers
commonly track
sales in retail
Alternative Input Devices Audio-Visual (Multimedia) Input Devices
Microphones can accept auditory input. A
microphone requires a sound card in the PC, to
digitize analog sound signals, and convert digital
sound signals to analog form.
PC video cameras digitize full-motion images.
Digital cameras capture still images. These cameras
break images into pixels and store data about each
Categories of Monitors
CRT Monitors
Flat-Panel Monitors
Comparing Monitors
Video Controllers
Monitors Categories of Monitors
Monitors are categorized by the technology they use:
Cathode ray tube (CRT) monitors
Flat-panel displays
Monitors CRT Monitors
In CRT monitors, electrons are fired at phosphor
dots on the screen.
The dots are grouped into pixels, which glow when
struck by electrons.
Monitors Flat-Panel Monitors
Most flat-panel monitors use liquid crystal display
(LCD) technology.
Passive matrix LCD uses a transistor for each row
and column of pixels.
Active matrix LCD uses a transistor for each pixel on
the screen.
Thin-film transistor displays use multiple
transistors for each pixel.
Monitors Comparing Monitors
When comparing monitors, consider four features:
• Size
• Resolution
• Refresh rate
• Dot pitch
Monitors Video Controllers
• The video controller is an interface between the
monitor and the CPU.
• The video controller determines many aspects of a
monitor's performance, such as resolution or the
number of colors displayed.
• The video controller contains its own on-board
processor and memory, called video RAM (VRAM).
Sound Systems
• Multimedia PCs come with a sound card, speakers,
and a CD-ROM or DVD drive.
• A sound card translates digital signals into analog
ones that drive the speakers.
• With the right software, you can use your PC to edit
sounds and create special sound effects.
• Categorizing Printers
• Evaluating Printers
• Dot Matrix Printers
• Ink Jet Printers
• Laser Printers
Printers Categorizing Printers
Printers fall into two categories:
• Impact printers use a device to strike an inked
ribbon, pressing ink from the ribbon onto the paper.
• Non-impact printers use different methods to place
ink (or another substance) on the page.
Printers Evaluating Printers
When evaluating printers, consider four criteria:
Image quality – Measured in dots per inch (dpi). Most
printers produce 300 – 600 dpi.
Speed – Measured in pages per minute (ppm) or
characters per second (cps).
Initial cost – Consumer printers cost $250 or less, but
professional printers can cost thousands of dollars.
Cost of operation – This refers to the cost of supplies
used by the printer.
Printers Dot Matrix Printers
Dot matrix printers are a common type of impact
A dot matrix printer's print head contains a cluster
of pins. The printer can push the pins out to form
patterns in rapid sequence.
The pins press an inked ribbon against the paper,
creating an image.
Printers –
Ink Jet Printers
• Ink jet printers are an example of non-impact
• The printer sprays tiny droplets of ink onto the
• Ink jet printers are available for color and black-andwhite printing.
Laser Printers –
How Do Laser Printers Work?
Laser printers are non-impact printers.
They use heat and pressure to bond particles of
toner to paper.
Laser printers are available for color and blackand-white printing.
le s s o n 2 r e v ie w
E s s e n t ia l c o n c e p t s
Identify the five key groups on a standard computer
Identify the five essential techniques for using a
List three categories of alternative input devices.
Name two categories of computer monitor.
List the four criteria you should consider when
evaluating monitors.
List the three most commonly used types of printers.
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