sutikno Umum

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Hardware: Input &

Output

5.1 Input & Output

5.2 Input Hardware

5.3 Output Hardware

5.4 I/O Quality of Life: Health & Ergonomics

5.5 Future of Input & Output

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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

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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

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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

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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

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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

(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

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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

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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

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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

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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

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Input Hardware

Scanning & Reading Devices



Source Data Entry devices create machine-readable

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

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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

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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

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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

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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

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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

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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

(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

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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

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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

(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/

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Output Hardware



Softcopy

Data that is shown on a display screen or is in audio or voice form; exists electronically

Output that is ephemeral in nature



Hardcopy

Printed and film output

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Output Hardware

Display Screens

_{Making a good choice when choosing a display}

Dot pitch (dp) is the amount of space between adjacent pixels

(picture elements) on screen

 The closer the pixels, the crisper the image  Get .25 dp or better

Resolution refers to the image sharpness

 The more pixels the better the resolution  Expressed in dots per inch (dpi)

Color depth or bit depth is the number of bits stored in a dot

 The higher the number the more true the colors  24-bit color depth is better than 8-bit color depth

Refresh rate is the number of times per second the pixels are

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Output Hardware

Monitors



Cathode Ray Tube (CRT) is a vacuum tube used in a

computer or terminal display screen

Watch the PC ads to make sure your monitor is included



Flat panel displays are made of 2 plates of glass

separated by a layer of liquid crystals that line up to

transmit or block light

Preferable to CRTs because they take up less room on the desktop

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Output Hardware

Monitors

_{Video Standard}

SVGA

XGA

SXGA

UXGA

QXGA

_{Principal resolution (pixels)}

800 x 600

1024 x 768

1280 x 1024

1600 x 1200

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Output Hardware

Printers

_{Impact Printers}

_{Laser Printers}

_{Inkjet Printers}

_{Thermal Printers}

_{Form characters or images by striking a}

print hammer or wheel against an ink ribbon

 _{Dot matrix printers}

Use drums and toner like in photocopiers

 Page Description Language (PDL)

 PostScript and PCL are PDL types

 Produce crisp, professional pages

_{Spray ink from 4 nozzles at high speed}

 Quiet, inexpensive color printers

 Often less precise than laser printers

Low to medium resolution printers that use

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Output Hardware

Plotters



A specialized output device designed to produce large

high-quality graphics in a variety of colors

The earliest output device that could produce graphics Pen plotters use one or more colored pens

Electrostatic plotters lie partially flat on a table and use toner like photocopiers

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Output Hardware

Mixed Output



Sound output

You need a sound card and sound software

Good equipment can produce very high-quality 3-D sound



Voice Output

TTS systems (text to speech) are becoming popular

Requires a sound card and speakers with TTS software



Video Output

Requires a powerful processor and a video card

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I/O Quality of Life: Health &

Ergonomics



PCs impact health

Overuse injuries and repetitive stress injuries

Result when muscle groups are forced through fast,

repetitive motions

May effect data-entry operators who average 15,000

keystrokes an hour

May effect PC users whose monitor, keyboard, and

workstation are not arranged for comfort

Carpal tunnel syndrome is caused by pressure on the

median nerve in the wrist, caused by short repetitive movement

Computer vision syndrome is eyestrain, headaches, and

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I/O Quality of Life: Health &

Ergonomics



Ergonomics is the methodology of designing a

workplace to make working conditions and equipment

safer and more efficient

Keyboards must be placed at the correct height depending on each worker’s size

Monitor refresh rates must be fast enough to avoid eyestrain

Monitor heights must be correct for comfortable viewing Sound-muffling should be used for loud printers to reduce

workplace noise

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Future of Input and Output



This is a fruitful area for research, including

Intelligent sensors

More data input from remote locations More source data automation

Input help for the disabled

More sophisticated touch devices Better speech recognition

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Future of Input and Output



This is a fruitful area for research, including

Pattern-recognition and biometric devices Brainwave devices

Better and cheaper display screens Improved video on PCs

3-Dimensional output