Standard Methods of Input

• The Keyboard
• The Mouse
• Variants of the Mouse

The Keyboard

• If the CPU is the brain of the computer, then the
input devices are its eyes and ears.

• The keyboard was one of the first peripherals to be
used with computers, and it is stil the primary
input device.

• The Standard Keyboard Layout

• Ergonomic Keyboards

• How a Keyboard Works

The Keyboard – Standard Keyboard Layout

• A standard computer keyboard has about 100 keys.

• Most keyboards use the QWERTY layout, named for
thefirst six keys in thetop row of leters.

Most keyboards have keys arranged in five groups:

1. Alphanumeric keys

2. Numeric keypad

3. Function keys

4. Modifier keys

5. Cursor-movement keys

The Keyboard – Ergonomic Keyboards

• Long periods of keyboard use can cause injuries.

• An ergonomicaly correct keyboard can help you
avoid injuries.

• You also can avoid injuries by adopting correct
keyboarding practices.

The Keyboard – How a Keyboard Works

When you pres a key:

•The keyboard controler detects the keystroke.

•The controler places a scan code in the keyboard
bufer, indicating which key was pressed.

•The keyboard sends the computer an interrupt
request, teling the CPU to accept the keystroke.

•An interrupt is a signal; it notifies a program that an
event has occurred.

The Mouse

• What is a Mouse?

• Mouse Techniques

The Mouse – What is a Mouse?

•The mouse is a pointing device. You use it to
move a graphical pointer on the screen.

•The mouse can be used to issue commands, draw,
and perform other types of input tasks.

The Mouse – Mouse Techniques

Using the mouse involves five techniques:

1. Pointing; Move the mouse to move the on-screen

2. Clicking; Pres and release the left mouse buton

3. Double-clicking; Press and release the left mouse
buton twice.

4. Dragging; Hold down the left mouse buton as you
move the pointer.

5. Right-clicking; Press and release the right mouse buton.

Variants of the Mouse

• Trackbals

• Trackpads

• Integrated Pointed Devices

Variants of the Mouse – Trackbals

• A trackbal is like a mouse turnedupside-down.

• Use your thumb to move the exposed bal and your
fingers to pres the butons.

Variants of the Mouse – Trackpads

•A trackpad is a touch-sensitive pad that provides the
same functionality as a mouse.

•To use a trackpad, you glide your finger across its

•Trackpads provide a set of butons that function like
mouse butons.

Variants of the Mouse- Integrated Pointing Devices

•An integrated pointing device is a smal joystick built
into the keyboard.

•To use an integrated pointing device, you move the

•These devices provide a set of butons that function
like mousebutons



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