Matakuliah
Tahun
Versi
: T0604-Pengantar Teknologi Informasi
: 2008
: 2.0/0.0
Pertemuan 11
Hardware: Input Devices
Sumber:
Chapter 5. Hardware: Input &
Output, p.251
Williams, B.K, Stacy C. Sawyer (2007).
Using Information Technology: A
Practical Introduction to Computers &
Communications. Seventh Edition,
McGraw-Hill, New York. ISBN-13: 978-007-110768-6
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• menjelaskan jenis-jenis dan kegunaan
serta cara kerja peralatan input (C2)
2
Outline Materi
• Input & Output
• Input Hardware
3
Input & Output
• Input Hardware
– Devices that translate data into a form the
computer can process
– Translates words, numbers, sounds, and
pictures into binary
• Output Hardware
– Devices that translate information processed
by the computer into a form humans can
understand
– Translates binary into words, numbers,
sounds, and pictures
5-4
Input Hardware
• Keyboards: convert letters, numbers, and characters into
electrical signals
– English keyboards differ from foreign language keyboards
– Follow this link to see what a Russian Cyrillic keyboard
layout looks like
• http://www.geocities.com/fontboard/cyrillic.html
– Even languages that are close to ours like German have
different keyboard layouts, such as can be seen on
Microsoft’s web site
• http://www.microsoft.com/globaldev/keyboards/kbdgr.htm
– Even touch typists must watch their fingers when they travel
to Internet Cafes in foreign countries!
5-5
Input Hardware
• How keyboards work:
– You press a key
– This interrupts the current flowing through the circuits
– Processor determines where the break occurs
– It compares the location of the break with the (x,y) character
map for the language on the keyboard’s ROM chip
– A character is stored in 16-byte keyboard memory buffer
– Then sent to PC as a data stream via wire or wireless
connection
– OS interprets its own operating-system-specific commands
and sends the others to the application for interpretation
5-6
Input Hardware
• Keyboard types
• 104 – 108 keys desktop standard
• 85 keys for laptops
– Wired
• Connect to CPU via a serial or USB port
– Wireless use either
•
•
•
•
IR (infrared) technology
Radio Frequency (RF) technology
Require line of sight to connect
Virtual keyboard used with PDAs and smartphones
5-7
Input Hardware
Terminal Types
• Dumb Terminals
– a.k.a. Video Display Terminal (VDT)
– Has display screen and keyboard
– Can do input and output only – no data processing
• Intelligent Terminals
– Has screen, keyboard, and memory
– Can perform some local functions
• Internet Terminals
– Powers directly up into a browser
• Web terminal displays web pages on a TV set
• Network computer is a stripped-down PC to connect people to
networks
• Online game player connects to internet for online gaming
• PC/TV merges a full-blown PC with a TV
• PDA is a handheld computer with a tiny keyboard
5-8
Input Hardware
• PDA Keyboards
– Problem: Make them too small and they are
unusable
– Problem: Make them too big and the PDA is
too big
– Solutions:
• Some PDAs use a stylus
• Some PDAs use a foldable keyboard
• Some PDAs use a 20-key mini-keyboard
5-9
Input Hardware
Pointing Devices
• Control the position of the cursor or pointer in the screen and
allow the user to select options displayed on the screen
• Mouse is the principal pointing tool
– Rolls around on a mouse pad or desktop and directs a
pointer on the computer’s display screen
•
•
•
•
Ball inside the mouse touches the desktop and rolls around
Two internal rollers touch the ball
One roller picks up motion in x (up), the other in y (down)
The rollers turn a shaft that spins a disk that breaks an LED signal
into light pulses that are seen by an infrared sensor
• Processor chip in mouse reads the pulses and turns it into binary
Discussion Question: What is the difference between “cursor” and “curser”?
5-10
Input Hardware
Pointing Devices
• Trackball
– A movable ball mounted on top of a stationary device
– Good for locations where a mouse couldn’t move
enough
– Requires more frequent cleaning to remove finger oils
• Touchpad
– To use: slide your finger over this small flat surface
– Click by tapping you finger on the surface
– May require more practice to use than a mouse
• Pointing Stick
– Looks like a pencil eraser in the lower center of a
laptop keyboard
5-11
Input Hardware
Pointing Devices
• Touch Screens
– A video display screen sensitized to receive input
from a finger
– Cruder than a mouse, because fingers are big
– Problems: touch screens that show a display that is
not precisely aligned with the input
• Pen input
– Use a pen-like stylus for input rather than typing on a
keyboard
– Use handwriting recognition to translate cursive
writing into data
5-12
Input Hardware
• Light Pen
– A light-sensitive pen-like device that uses a wired
connection to a computer terminal
– Bring the pen to the desired point on the display
screen and press a button to identify the screen
location
– Used in situations that require gloves
– Less crude than a touch screen
• Digitizer
– Uses an electronic pen or puck to convert drawings
and photos to digital data
– Digitizing tablets are used in architecture
5-13
Input Hardware
Scanning & Reading Devices
• Source Data Entry devices create machinereadable data and feed it directly into the
computer
– Scanners
• Use light-sensing equipment to translate images of text,
drawings, and photos into digital form
• Image scanners are used in electronic imaging
• Resolution refers to the image sharpness, measured in dots
per inch (dpi)
• Flatbed scanners work like photocopiers – the image is
placed on the glass surface, then scanned
• Other types are sheet-fed, hand-held, drum, and pen
scanners
5-14
Input Hardware
Bar-Code Readers
• Photoelectric (optical) scanners that translate bar code
symbols into digital code
• The digital code is then sent to a computer
• The computer looks up the item and displays its name and pricing
info
– Bar code types
• 1D holds up to 16 ASCII characters
• 2D can hold 1,000 to 2,000 ASCII characters
• 3D is “bumpy” code that differentiates by symbol height
– Can be used on metal, hard rubber, other tough surfaces
5-15
Input Hardware
Mark Recognition Readers
• Bar code readers
– MICR – Magnetic-ink character recognition
• Uses special magnetized inks
• Must be read by a special scanner that reads this ink
– OMR – Optical mark recognition
• Uses a special scanner that reads bubble marks
• Used in standardized tests like the ACT and SAT
– OCR – Optical character recognition
• Converts scanned text from images (pictures of the text) to
an editable text format
• You use this to read in non-computer documents where you
don’t have the source files
5-16
Input Hardware
Fax Machines
• Facsimile Transmission Machines – scan an
image and send it as electronic signals over
telephone lines to a receiving fax, which prints
out the image on paper
– Dedicated fax machine
• Is a stand-alone unit that only sends and receives faxed
documents
– Fax modem
• Is a circuit board installed in the PC
• Is a modem that can send and receive faxes
– Can send documents directly from your word processor to a fax
machine
– Saves you printing out the document, then faxing it
5-17
Input Hardware
Audio Input Devices
• Records analog sound and translates it
into digital files for storage and processing
• Two ways to digitize audio
– Sound Board
• An add-on board in a PC that converts analog
sound to digital sound, stores it, and plays it back
to speakers or amp
– MIDI Board
• Stands for Musical Instrument Digital Exchange
• Uses a standard for the interchange between
musical instruments, synthesizers, and PCs
5-18
Input Hardware
Webcams and Video-input Cards
• Webcams
– Video cameras attached to a computer to record live moving
images then post them to a website in real time
– Require special software, usually included with the camera
• Frame-grabber video card
– Can capture and digitize 1 frame at a time
• Full-motion video card
– Can convert analog to digital signals at rates up to 30 frames per
second
– Looks like a motion picture
Discussion Question: Why might it be unwise to install a webcam on your PC?
5-19
Input Hardware
Digital Cameras
• Use a light-sensitive processor chip to capture
photographic images in digital form and store
them on a small diskette in the camera or on
flash memory cards
– Most can be connected to a PC by USB or FireWire
– Can allow you to take more pictures and decide which
ones to print and save
– But pictures are subject to loss by diskette or flash
memory failure or computer virus if you store them on
the PC
5-20
Input Hardware
Camera Phones
• Digital cameras are now on cellphones
– Convenience of being able to take photos, then
instantly email or message them to someone else
– Can provide instant record of traffic accidents, etc
Discussion Question: Why do you suppose cellphones are now banned on
secure U.S. military bases? Where else besides military bases might they pose a
security problem?
5-21
Input Hardware
Speech-Recognition Systems
• Uses a microphone or telephone as an input
device. Converts a person’s speech into digital
signals by comparing against 200,000 or so
stored patterns.
– Used in places where people need their hands free –
warehouses, car radios, stock exchange trades
– Helpful for people with visual or physical disabilities
that prevent them from using other input devices
– Still not easy enough to use to substitute for the
mouse/keyboard for fast document processing
• ScanSoft’s Open Speech Dialog
• Apple Speech Recognition
• ScanSoft’s Navigon MobileNavigator 5
5-22
Input Hardware
RFID Tags
• Radio-frequency ID tags are based on an
identifying tag with a microchip containing
specific code numbers
– Scanners use radio waves to read them and match
the codes to a database
– Enables items to be tracked without physical contact
•
•
•
•
Drivers put RFID tags in cars to automatically pay tolls
FDA is tagging certain drugs with RFID to avoid counterfeits
Carmakers are using it for car electronic keyless entry
RFID tags are implanted under skin of pets to aid in recovery
and identification when they get lost
5-23
Input Hardware
Biometrics
• The science of measuring individual body
characteristics, then using them to identify a
person through a fingerprint, hand, eye, or facial
characteristic
– Becoming a big business as more companies
become concerned about security
– Makes identity theft much more difficult when records
are identified by biometrics as well as passwords
– For more information see
• http://www.xtec.com/home.html
• http://www.identix.com/
• http://www.precisebiometrics.com/
5-24
Kesimpulan
25