Chapter 3 

Hardware Basics: Peripherals 

Input: From Person to Processor

Keyboard

The most familiar input device

Used to enter letters, numbers and special characters

Standard keyboard

Ergonomic keyboards

-To address possible medical problems

Wireless keyboard

Folding keyboards

-Used with palm-sized computers

One-handed keyboards  

Pointing Devices

1.       Mouse

2.      Touchpad

3.      Pointing stick

4.      Trackball

5.      Joystick

6.      Graphics tablet

7.      Touch screen

8.      Stylus

Reading Tools

Read marks representing codes specifically designed  for computer input

Optical-mark readers 
Magnetic-ink character readers 

Bar-code Readers

Pen scanners 

Tablet PC 

Smart whiteboard 

Radio Frequency Identification Readers (RFID)

Digitizing the Real World

Scanners capture and digitize printed images
a. Flatbed  b. Slide c. Drum

Digital camera

Snapshots captured as digital images

Digital images stored as bit patterns on disks or other digital storage media 

Video digitizer

Capture input from a:

Video camera

Video cassette recorder or television

Convert it to a digital signal

Stored in memory and displayed on computer screens

Videoconferencing

People in diverse locations can see and hear each other

Used to conduct long-distance meetings

Video images transmitted through networks

Sheet-fed

Audio digitizers

1. Digitize sounds from

*Microphones

*Other input devices

2. Digital signals can be

*Stored

* Further processed with specialized software

A digital signal processing chip compresses the stream of bits before it is transmitted to the CPU.

Speech recognition software

Converts voice data into words that can be edited and printed

Screen Output

1. A monitor or video display terminal (VDT) displays characters, graphics, photographic images, animation and video.

Video adapter—connects the monitor to the computer

VRAM or video memory—a special portion of RAM to hold video images

2. The more video memory, the more picture detail is displayed.

3. Monitor size: Measured as a diagonal line across the screen

4. Resolution: The number of pixels displayed on the screen

Pixels (or picture elements): tiny dots that compose a picture

The higher the resolution, the closer together the dots.

5. Image quality is affected by resolution and color depth (or bit depth).

Color depth refers to the number of different colors a monitor displays at one time.

Solid-State Storage Devices

Flash memory is an erasable memory   

 chip:

Sizes range from 16 MB to 1 GB

Compact alternative to disk storage

Contains no moving parts

Designed for specific applications such as storing pictures in digital cameras

Likely to replace disk and tape storage

CD-ROM

Optical drives that read CD-ROMs 

CD-R

WORM media (write-once, read many) 

CD-RW

Can read CD-ROMs and write, erase and rewrite data onto CD-R & CD-RW disks 

DVD (Digital Versatile Disks)

Store and distribute all kinds of data

Hold between 3.8 and 17 gigabytes of information

DVD-ROM drives

Can play DVD movies, read DVD data disks

Read standard CD-ROMs, and play audio CDs

Read-only: can’t record data, music, or movies 

DVD-RAM drives

Can read, erase, and write data (but not DVD video) on multi-gigabyte DVD-R (but not CD-R or CD-RW) media

Storage devices are capable of two-way communication with the computer. Because of their high-speed random access capability, magnetic disks are the most common forms of storage on modern computers.

Network connections make it possible for computers to communicate with one another directly.

~ooo~