Input Output

Computer Hardware

By. Nikunj Nayak

CMS - Ganpat University.

Input Technology

InputDevices

SecondaryStorage

OutputDevices

ControlUnit

PrimaryStorage

ALU

Registers

The CPU

CommunicationDevices

Sources of Data for the Computer• Input: Those parts of the computer receiving information to programs. Input

devices are used to transfer user data and instructions to computer.

• Two types of data stored within a computer:

1. Original data or information: Data being introduced to a computing system for the first time.

Computers can deal directly with printed text, pictures, sound, and other common types of information.

2. Previously stored data or information: Data that has already been processed by a computer and is being stored for later use.

Examples: Floppy disks, DVD disks, and music CDs.

Connecting Hardware to the Computer• Port: The pathway for data to go into and out of the computer from external

devices such as keyboards.

Ports follow standards that define their use. SCSI, USB: Multiple peripheral devices (chain). RS-232, IDE: Individual peripheral devices.

• Peripheral device: A piece of hardware like a printer or disk drive, that is outside the main computer.

• Hardware needs software on the computer that can service the device.

• Device driver: Software addition to the operating system that will allow the computer to communicate with a particular device.

Input Devices• Common Basic Technologies for Storing Binary Information:

1. Electronic2. Magnetic3. Optical

Electronic Circuits:

• Most expensive of the three forms for storing binary information.

• A flip-flop circuit has either one electronic status or the other.

• Electronic circuits come in two forms:

1) Permanent2) Non-permanent

Input DevicesMagnetic Technology

• The medium that stores the magnetic information.– Example: Floppy disk. Tiny spots on the disk are magnetized to represent

0s and 1s.

• The device that can “read” that information from the medium.– The drive spins the disk.– It has a magnetic sensing arm that moves over the disk.

Optical Technology

• Uses lasers to “read” the binary information from the medium, usually a disc.

• Millions of tiny holes are “burned” into the surface of the disc.

Input Devices

Input hardware: Those that deal with original data.

– Keyboard Devices

– Point-and-draw Devices

– Scanning Devices

– Voice recognition hardware

– Vision Input Devices

KEYBOARD DEVICES• Keyboard devices allow input into the computer system by pressing a set of

keys, mounted on board connected to the computer system.

1. General-purpose keyboard:

• The most popular keyboard used today is the 101-keys with a traditional QWERTY cursor-control keys.

• It is so called because the arrangement of its alphanumeric keys in the upper left row.

KEYBOARD DEVICES2. SPECIAL-PURPOSE KEY BOARD

• These are standalone data entry system used for computers deployed for specific applications.

• A very typical example of such keyboards can be seen at the Automatic teller machines or the ATMs where the keyboard is required for limited functionality by the customer.

KEYBOARD DEVICES2. KEY-TO-TAPE, KEY-T0- DISK, KEY-TO-DISKETTE

• These are standalone data entry stations. These units usually have a small processor attached to a keyboard and a visual display unit.

• The processor checks for the accuracy of data at the time of entry.

TYPES OF KEYS• Alphanumeric keypad: Contains keys for the English alphabets,0 to 9 numbers,

special characters*+ - / [ ] etc.

• 12Function keys: These are keys labeled F1,F2……F12 and are a set of user programmable function keys.

• Special- function keys: these keys have special functions For example, enter key is used to send the keyed-in data into the memory. other keys shift, alt, tab etc.

• Numeric keypad: Consists of keys having numbers(0 to 9) and mathematical operators(+ - * /) defined on them.

• Cursor-control keys: Defined by the arrow keys used to move the cursor in the direction indicated by the arrow(top, down, left, right)

POINT-AND-DRAW DEVICES1. Mouse: A mouse is a small device that a computer user pushes across a desk

surface in order to more actions possible from that position.

2. Track ball: The track ball is a pointing device that is much like an inverted mouse.

It is more convenient and requires much less space than the mouse since here the whole device is not moved(as in the case of mouse).

POINT-AND-DRAW DEVICES3. Joystick: The joystick is a vertical stick that moves the graphic cursor in the

direction the stick is moved.

Video games, training simulators, and control panels of robots are some common uses of a joystick.

4. Light pen: The light pen is a pen-shaped device allowing natural movement on the screen.

It is made up of a light sensitive cell and a lens assembly designed in such a way that it focuses onto itself any light in its field.

Light pens are typically used in CAD (computer aided device) applications to directly draw on screen.

POINT-AND-DRAW DEVICES

POINT-AND-DRAW DEVICES5. Touch screen: A touch screen is probably one of the simplest and most

intuitive of all input devices.

It uses optical sensors in, Or near, The computer screen that can detect the touch of a finger on the screen.

Once the user touches a particular screen position, Sensor communicate the position to the computer.

SCANNING DEVICE• Scanning devices are input devices used for direct data entry from the source

document into the computer system.

• Scanners facilitate the capturing of information and storing it in a graphical format for displaying it back on the graphical screen.

1. Scanner: two types

1) Contact scanner: Hand-held contact scanners make contact as they are brushed over the

printed matter to be read. Hand-held scanners are used where the information to be scanned or

the volume of documents to be scanned is very low.

2) Laser scanner(Flat-bed scanner): These scanners are more versatile and can read data passed the near

scanning area.

2. OPTICALMARK RECOGNITION(OMR)

OMR devices can sense marks on computer readable paper.

This kind of device is typically used by academic institution to grade aptitude tests.

These answer sheets can then be directly read by the optical mark recognition devices and can be used for further processing by the computer.

SCANNING DEVICE

SCANNING DEVICE3. Magnetic ink character recognition(MICR):

Magnetic ink character recognition (MICR) is similar to optical mark recognition and is used exclusively by the banking industry.

MICR devices are used by the to read the banking industry account numbers on cheques directly and subsequently do the necessary processing.

4. Optical bar code reader(OBR)

Data coded in the from of small vertical lines from the basis of bar coding.

Alphanumerical data is represented using adjacent vertical lines called Bar codes.

Example of a bar code used on one of the books for its unique identification.

SCANNING DEVICE

SCANNING DEVICE

5. Digitizer:

Digitizers are used to convert drawings or pictures and maps into a digital format for strong into the computer.

Digitizers see most common usage by architects and engineers as a tool for Computer Aided Designing.

SCANNING DEVICE6. Electronic-card reader:

Card reader are devices that also direct data into a computer system.

The electronics-card reader is connected to a system and read the data encoded on a electronic card and transfers it to the computer system for further processing.

E.g.. smart card

VOICE RECOGNITION DEVICES

• One of the most exciting areas of research involves the recognizing of an individual human voice as the basis of input to the computer system.

• Eliminating the keying in of data, basic commands can very easily be given, facilitating at quick operation

VISION-INPUT DEVICES

• Vision input devices allow data input in the from of images.

• It usually consists of a digital camera, which focuses on the object whose picture is to be taken.

Characteristics of Input Devices

The four most important characteristics of storage devices:

– Speed and access time– Cost / Removable versus non-removable– Capacity– Type of access

Characteristics of Input Devices

Speed (Access time)

How fast information can be taken from or stored onto the computer memory device’s medium.

– Electronic circuits: Fastest to access.• 40 billionths of a second.

– Floppy disks: Very slow in comparison.• Takes up to 1/2 second to reach full speed before

access is even possible.

Characteristics of Input Devices

Cost

– Megabyte: A Million bytes.– Gigabyte: A billion bytes.

– Two parts to a removable secondary storage device:• The cost of the medium. (Cheaper if bought in quantity)• The cost of the drive.

Examples: Cost for drive Cost for medium

Floppy drive (1.4MB) 59.00 .50

Zip 100 (100 MB) 99.00 10.00

CD-WR (650 MB) 360.00 and up 1.00

Characteristics of Input Devices

Capacity

The amount of information that can be stored on the medium.

Unit Description Approximate Size1 bit 1 binary digit1 nibble 4 bits1 byte 8 bits 1 character1 kilobyte 1,024 bytes 1/2 page, double spaced1 megabyte 1,048,576 bytes 500,000 pages

1 million bytes1 gigabyte 1,073,741,824 bytes 5 million pages

1 billion bytes1 terabyte 1 trillion bytes 5 billion pages

Characteristics of Input Devices

Type of Access

• Sequential - Obtained by proceeding through the storage medium from the beginning until the designated area is reached (as in magnetic tape).

• Random Access - Direct access (as in floppy and hard disks).

Output Technology

Output:

• Those parts of the computer that provide results of computation to the person using the computer.

• Output units store and display information (calculated results and other messages) for us to see and use.

Output Technology

InputDevices

SecondaryStorage

OutputDevices

ControlUnit

PrimaryStorage

ALU

Registers

The CPU

CommunicationDevices

Output Technologies

• Display Devices

• Printers

• Plotter

• Computer Output Microfilm(COM)

• Voice Response System

• Multimedia

Display devicesDisplay screen technology may be one of the three categories:

(A) Cathode ray tube(CRT): The main components of a cathode ray terminal are the electron gun, the electron beam controlled by an electromagnetic field, and a display screen which is phosphor-coated.

There are two types of CRT displays:

1) Vector CRT display: In which the electron beam is directed only to places where the images is to be created.

2) Raster scan display: In which image is projected on screen by directing the electron beam across each row of the picture elements from top to the bottom of the screen. Full color display.

Display devices• The quality of display is indicated by resolution.

• Resolution: The number of horizontal & vertical pixel. (800 X 600), (640 X 768), (1024 X 1024) etc..

• CGA (Color Graphic Adapter): resolution of (320 X 200) and support up to 16 colors.

• EGA (Extended Graphic Adapter): resolution of (640 X 350) and support up to 16 colors.

• VGA (Video Graphic Adapter): resolution of (640 X 480) and support up to 256 colors.

• Super VGA: Resolution ranging (800 X 600) to (1280 X 1024) and supporting up to 256 or more colors.

Display devices

B. Liquid crystal display(LCD)

Introduced in watches and clocks in the 1970s and is now applied terminals. In this, The cathode ray tube was replaced by liquid crystal to produce the image.

It does not have color capability and image quality is relatively poor.

Low energy consumption.

C. Projection display

These system are connected to the computer and whatever appears on the computer terminal gets enlarged and projected on large screen.

Display devices

Monitors:

• Monitors use a cathode ray tube (CRT)to display information.

• It resembles a television screen and is similar to it in other respects.

Multimedia projectors:

• A multimedia projectors is an output to project information from the computer onto a large screen so that it can be viewed by a large group of people.

Printers• Printers are used for producing output on paper.

• These printers can be classified into categories based on:

1. Printing Technology2. Printing Speed3. Printing Quality

Printing technology:

• Printing can be classified as impact or non-impact printers, based on the technology they use for producing output.

1. Impact Printers:

– Impact printers use variations standard typewriter printing mechanism where a hammer strikes the paper through an inked ribbon.

– Dot matrix printers and character printers fall under this category.

2. Non Impact Printers:

– Non –impact printers do not touch the paper when creating an image. They use chemical, heat or electrical signals to etch symbols on paper.

– Inkjet, laser and thermal printers fall under this category of printers.

Printers

Printing speed:

– Refers to the number of characters printed in a unit of time.

– Based on speed these may be classified as character printers, line printers and page printers.

– Printer speeds are measured in terms of CPS, LPM, PPM.

Printing quality:

– Is determined by the resolution of printing and is characterized by number of dots that can be liner inch, horizontally or vertically.

– It is measured in terms of dots-per-inch or DPI

1. NLQ (Near letter quality): resolution of about 300 dpi.

2. LQ (letter quality): resolution of about 600 dpi.

3. NTQ (Near-typeset-quality): resolution of about 1200 dpi.

4. TQ (Typeset quality): resolution of about 2000 dpi.

Printers

Types of Printers• Dot Matrix

Dot matrix printers were the most popular impact printers used in personal computing. These printers use a print head consisting of a series of small pins to strike a ribbon coated with ink, causing the ink to the transfer to the paper at the point of impact.

• InkjetInkjet printers use a series of nozzles to spray drop of ink directly on the paper. These therefore fall under the category of non-impact printers.

• LaserLaser printers use dry ink, static electricity, and heat to place and bond the ink onto paper. They use a combination of laser and photocopier technology.

PLOTTERSPlotters are used to produce output on paper. It is a device capable of producing charts, drawings, graphics, maps etc. It is much like a printer but is designed to print graphs instead of alphanumeric characters.

(a) Flatbed plottersFlatbed plotters have a flat base like drawing board on which the paper is laid. One or more arms, each of them carrying an ink pen, move across the paper to draw.

(b) Drum plottersDrum plotters use a drum revolver to move the paper during printing. The arm carrying a pen moves only in one direction, perpendicular to the direction of the motion of the paper.

COMPUTER OUTPUT MICROFILM(COM)• COM is a process characterized by copying/printing data from media located

on PCs, mini or mainframe computer onto a microfilm.

• It consists of a high speed recorder, Which transfer digital data onto a microfilm using laser technology, and processor that develops the microfilm once exposed to the light source.

• COM translates information normally held on magnetic tape into miniature images on a microfilm.

• The device displays information as characters on a CRT screen and then using photographic methods records the display onto the film.

• A special reader/printer can subsequently be used to view the processed film.

• Reader project display on screen and printer produce hardcopy.

• Very expensive technique to recording and storing the data.

• Used in insurance companies, banks, government agencies.

VOICE RESPONSE SYSTEMS• Voice response systems enable the computer to talk to its users. It consists of

an audio-response device that produces the audio output.

• Voice response systems are typically of two types:

1. Voice reproduction system: Voice reproduction system produce an audio output by selecting the appropriate response from a predefined set of responses. These responses may be in the from of speech, musical sounds, alarms, Or other sound.

e.g. : Automatic answering machine, Talking Alarm Clock

2. Speech Synthesizer: A speech access system converts text to spoken words. The system consists of a synthesizer that does the speaking and the screen access program that directs the synthesizer.

e.g. : Screen Reader.

Multimedia

Multimedia:

• Multimedia means multi and media refers to communication / transfer medium.

• Multimedia is any combination of text, graphic art, sound, animation and video elements delivered to you by your computer or any other electronic means”.

Elements of Multimedia:

Text

Graphics

Sound

Animation

Video

ELEMENTS OF MULTIMEDIAText

• Text containing word and symbols, is the most common from of communication.

• It is one of the popularly used mediums of appearance that is used to deliver information accurately and in detail.

Graphics

• Pictures/graphics enhance the overall look of a multimedia package.

• Pictures express more than normal text and are generally considered as the most important element of a multimedia application.

ELEMENTS OF MULTIMEDIAAnimation:

• Animation gives visual impact to your multimedia application.

• In simple terms, it can be defined as an entity moving across the screen. This entity could be a text object or an image.

Sound

• Sound is used to set the rhythm or a mood in a package. Speech gives an effect of a language for instance.

• Proper usage of sound can make all the difference between an ordinary multimedia presentation and professional one.

Video

• If pictures can paint a thousand words, then motion pictures can paint a million.

• Digital video is the most engaging of multimedia venues and powerful tool for bringing users closed to the real world.

ELEMENTS OF MULTIMEDIA

Thank You.