Chapter 3

From person to processor
Keyboard
-The most familiar input device
-Used to enter letters, numbers and special characters
àStandard keyboard
àErgonomic keyboards
To address possible medical problems
àWireless keyboard
àFolding keyboards
Used with palm-sized computers
àOne-handed keyboards
àKeyboards printed on membranes

Pointing Devices
- Mouse
-Touchpad
-Pointing stick
-Trackball
-Joystick
-Graphics tablet
-Touch screen
-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)
Input: From Person to Processor
Digitizing the Real World

-Scanners capture and digitize printed images.
-Flatbed
-Slide
-Drum
-Sheet-fed

−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

-Audio digitizers
-Digitize sounds from
- Microphones
- Other input devices
-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
−Sensors
-Designed to monitor physical
conditions
- Temperature, humidity, pressure
-Provide data used in:
- Robotics
- Environmental climate control
- Weather forecasting
- Medical monitoring
- Biofeedback
- Scientific research

From Pulses to People
−Screen Output
-A monitor or video display terminal (VDT) displays characters, graphics, photographic images, animation and video.
àVideo adapter—connects the monitor to
the computer
àVRAM or video memory—a special
portion of RAM to hold video images
-The more video memory, the more picture detail is displayed.

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

-Monitor classes
-CRTs (cathode-ray tubes)
-LCDs (liquid crystal displays)
- Overhead projection panels
- Video projectors
- Portable computers

−Paper Output
-Printers produce paper output or hard copy.
-Two basic groups of printers:
-Impact printers
-Line printers
-Dot-matrix printers
-Non-impact printers
Laser printers
−Laser beam reflected off a rotating drum to create
patterns of electrical charges
−Faster and more expensive than dot matrix printer
−High-resolution output
Inkjet printers
−Sprays ink onto paper to produce printed text and
graphic images
−Prints fewer pages/minute than laser printer
−High-quality color; costs less than laser printer

-Multifunction printer or MFP combines a scanner,
printer and a fax modem.
-A plotter can produce large, finely scaled engineering
blueprints and maps.

−Fax Machines and Fax Modems
-Facsimile (fax) machine
-Sending:
-scans each page as an image
-converts the image into a series of electronic pulses
-sends those signals over phone lines to another fax
-Receiving:
-uses the signals to reconstruct the image
-prints black-and-white facsimiles or copies of the originals
-Fax modem
-Connect from PC to fax machine via modem and phone line

-Output You Can Hear
-Sound card
-Enables the PC to:
-Accept microphone input
-Play music and other sound through
speakers or headphones
-Process sound in a variety of ways
-Synthesizers
-Used to produce music, noise

-Controlling Other Machines
-Output devices take bit patterns and
turn them into non-digital movements.
-Robot arms
-Telephone switchboards
-Transportation devices
-Automated factory equipment
-Spacecraft
-Force feedback joystick

Rules of Thumb: Ergonomics and Health

-Choose equipment that’s ergonomically designed.
-Create a healthy workspace.
-Build flexibility into your work environment.
-Rest your eyes.
-Stretch to loosen tight muscles.
-Listen to your body.
-Seek help when you need it.
Storage Devices: Input Meets Output
-Magnetic Tape
-Can store large amounts of information
in a small space at a relatively low cost
-Limitation: sequential data access
-Used mainly for backup purposes

-Magnetic Disks
-Random data access
-Floppy disks
àProvide inexpensive, portable storage
-Hard disks
àNon-removable, rigid disks that spin continuously and rapidly
àProvide much faster access than a floppy disk
-Removable media (Zip & Jaz disks)
àProvides high-capacity portable storage

−Optical Disks
-Use laser beams to read and write bits of information on the disk surface
-Not as fast as magnetic hard disks
-Massive storage capacity
-Very reliable

-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

−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
Computer Systems: The Sum of Its Parts
Personal Computer Design Classes
àTower systems
-Tall, narrow boxes, generally have more expansion slots and bays than
other designs
àFlat desktop systems
-Designed to sit under the monitor like a platform
àAll-in-one systems (like the iMac)
-Combine monitor and system unit into a single housing

-Laptop computers
Include all the essential components, including keyboard and pointing device,
in one compact box

-Ports and Slots Revisited
-The system or motherboard includes several standard ports:
-Serial Port for attaching devices that send/receive messages one bit at a time (modems)
-Parallel Port for attaching devices that send/receive bits in groups (printers)
-Keyboard/Mouse Port for attaching a keyboard and a mouse

-Other ports are typically included on expansion boards rather than the system board:
-A video port is used to plug a color monitor into the video board.
-Microphones, speakers, headphones, MIDI ports are used to attach sound equipment.
-An SCSI port allows several peripherals to be strung together and attached to a single port.
-A LAN port uses faster connections to a local-area network (LAN).

-Expansion Made Easy
-With the PC open architecture and the introduction of new interfaces, you can hot swap devices.
-USB (Universal Serial Bus) transmits a hundred times faster than a PC serial port
-Firewire (IEEE 1394) can move data between devices at 400 or more megabits per second. The high speed makes it ideal for data-intensive work, like digital video.
•FireWire 800, which offers 800 Mbps transfer speeds, was recently introduced on high-end Macintosh systems.

Putting It All Together
-A typical computer system might have several different input, output, and storage peripherals—the key is compatibility.
-Networks blur the boundaries between computers.
-Networked computers may have access to all the peripherals on a system.
-The computer is, in effect, just a tiny part of a global system of interconnected networks.
Inventing the Future: Tomorrow’s Peripherals
Tomorrow’s Storage
-Smaller disks that hold more
-A single electron memory chip the size of a thumbnail that can store all of the sounds and images of a full-length feature film

Tomorrow’s Output
-Flat-panel screens replacing desktop CRTs
-Retinal displays that work without a screen

Tomorrow’s Input: Sensors
-More sophisticated devices will serve as eyes, ears, and other types of sense organs for computer networks.

Lesson Summary
-Peripherals allow computer to communicate with the outside world and store information for later use information.
-The most common input devices today are the keyboard and the mouse. A variety of other input devices can be connected to the computer.
-Output devices perform the opposite function: They accept strings of bits from the computer and transform them into a form that is useful or meaningful outside the computer.
-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.