11.0 I/O (Input/Output) DEVICES

AA SOTP OPGSIGPSOG

I/O Technology

• People communicate in many different ways; these differences are reflected in variety of methods for interacting with computer systems

Input

Any data and instructions entered into the memory of a computer

Ex. Keyboard, pointing devices, touch screens, [pen, motion, voice, video] input, scanners, reading devices

Keyboard

• Contains keys you press to enter data and instructions into a computer or mobile device

• Translate keystrokes directly into electrical signals

• Pressing a key sends a coded signal to an integrated microprocessor (keyboard controller) → controller generates a bitstream output (scan codes) according to an internal program or lookup table

Dome Switch Keyboard

• ‘membrane keybaord’

• Uses a thin rubber or silicon layer with individual domes per key that collapse when pressed

• Quiet

  • might fail to register keystrokes if not pressed hard enough

Mechanical Keyboard

• Individual switches per key

• More expensive

• More tactile

Ergonomic keyboard

• Reduces the chance of repetitive strain injuries (RSIs) of wrist and hand

• Comfort, efficiency, safety

Pointing Devices

Track positions on a 2d surface

Mechanical mouse

Type of pointing device that uses a roller ball to move the wheels which specify movement along the X and Y axis

Optical mouse

• Type of pointing device

• Uses an optical scanner under with a high resolution.

• Microprocessor that compares many scans per second to determine the direction and speed of movement

Trackballs

Upside-down mechanical mice

Touchpad

Small, flat, rectangle pointing device that is sensitive to pressure and motion

Touchscreen

Flat panel display to function as both an input and output device

Additional components and layers are added to an LCD or LED to sense touch by a stylus, finger, or multiple fingers

Capacitive Touchscreen

• Conductivity of objects to sense location (like tapping on a screen)

• More sensitive and responsive

• Ex. Smartphones and tablets, laptops with touchscreens

Resistive Touchscreens

• Several layers, relies on pressure

• More accurate

• Ex. Older ATMs and POS systems, industrial equipment, Nintendo DS, older touch devices

Graphics Tablet

• digitizer

• detects and converts movements of a digital pen sent to the computer

Motion Input

• AKA gesture recognition

• Users can guide on-screen elements

Audio Input

• Entering sound like voice and music

• Music production software allows users to record, compose, mix, and edit music and sounds