I/O DEVICES

JINACCUS

A JINACCUS PRODUCTION

BACK TO BASICS Input is any data and instruction entered into the memory of

a computer. While output is any data that has been processed into useful form.

An input device is any peripheral used to provide data and control signals to an information processing system. Input and output devices make up the hardware interface between a computer and the user or external world.

Input devices accept data signals and translate them for usage and storage in the computer system. While Out put devices make processed data (information) available.

Some of the most integral parts/components of the computer are either input or output devices.

PURPOSE OF INPUT AND OUTPUT DEVICES

Before a computer can process your data, you need some method to input the data into the machine. Similarly, after the computer has processed your data, you often need to produce results/ output. This output can in the form of either softcopy or hardcopy.

Input and Output devices allow the computer to interact with the outside world. Without input and output devices, users would not be able to control it’ s functions; and without output devices users would not be able to obtain and share results.

INPUT DEVICES Some of the more prominent Input devices are as

follows: Keyboard MouseJoystickScanner

KEYBOARDThe keyboard is often the main vehicle used to input information

into the computer system. It is represented as a layout of buttons. Each button, or key, can be used to call upon a particular function of the computer. Connectivity

Desktop computer keyboards attach via cable to either a serial port, a keyboard port, or a USB port. They connect to the motherboard at the back of the PC (USB keyboards can connect in front if there front-side USB ports). Older keyboards used a 6-pin mini DIN connector known as PS/2, however, newer keyboards are typically USB or wireless.

A port is the point at which a peripheral attaches to a system unit.

SPECIALIZED KEYBOARD Specialized keyboards are used on some other types of

computer they are sometimes called membrane or overlay keyboards. They are used where fast input is needed and are ideally selected from a limited range of choices.

Speed

Compared to other keyboards, Specialized keyboards are faster in terms of data entries. They are fast for making non-text selections such as menu choice on a till of a fast-food outlet.

KEYBOARD!!

CASHIER TILL!!

MOUSE The mouse is a pointing device. It is used to control the

movement if a pointer on the screen. It is used to select

options from a menu or from a set of icons, to position

the cursor when editing a text and to draw shape (s) in a

design package.

MOUSE Connectivity The mouse is often connected to the system

unit via cable to either a serial port, a keyboard port, or a USB port on the CPU.

Speed In most cases (often concerning Graphic user

interface) a mouse makes data entry a great deal Faster and easier than a keyboard. It allows commands to be given by simply clicking or dragging instead of typing commands.

MOUSE!!

TRACKER BALL!!

JOYSTICK Joysticks and other game controllers can also be connected

to a computer as pointing devices. They are generally used for playing games, and not for controlling the on-screen cursor in productivity software.

JOYSTICKSConnectivity

Joysticks have come a long way from the traditional vertical lever and base combination. Modern joysticks, although different in appearance and function, generally have one thing in common, they attach to the computer through a 15-pin game port.

The adapter at the computer end is 15-pin female D-shell connector. The game port is a dedicated serial port that allows you to attach up to two joysticks to a system. This port's only resource need is an I/O port address (usually 201h).

SpeedJoysticks uses a low speed USB port.

This port has a speed rate of 1.5 Mbps. USB in general is very high speed.

15 Pin Game Port :

SCANNER A scanner is a device that images a printed page or

graphic by digitizing it, producing an image made of tiny pixels of different brightness and colour values which are represented numerically and sent to the computer.

SPECIALISED SCANNERSThere are many types of scanners some of these are:

Optical Mark ReaderThis device can sense the presence of a pen or pencil mark. It is

commonly used for processing large quantities of simple, repetitive data such as marking multiple-choice questions.

Optical Character ReaderThis device can recognize characters that are printed in a specific

type font. The optical character reader can distinguish one character from another by its shape.

The optical character reader scans the document and converts the shape sensed into a pattern of electronic signals. The sensed pattern is compared with the stored patterns of the characters. If a match is found, the character sensed is identified. If a match is not found, that part of the document is rejected.

Magnetic Ink ReaderCharacters are printed with an ink containing a substance that can

be magnetized. The character shapes are recognized by the magnetic ink character reader. MICR is used mainly in banks. Each cheque is printed with the cheque number, the bank's identification number, and the customer's account number.

Magnetic ink reader

SCANNERConnectivity

Scanners connect to a system unit via a FireWire port. This type of connector is similar to a USB port but is much faster.

SpeedIn terms of speed, scanners are faster than

keyboards as it eliminates manual data input and is more accurate as the device captures data directly from the source document.

OUTPUT DEVICES Some of the more prominent Input devices are as

follows: MonitorsPrinters Speakers

MonitorsMonitors are output devices that consist of a

viewing screen, in other words it is a device used by the computer to communicate interactively with the user.

Flat Screen Monitor !!!

SPECIALISED MONITORS A flat panel display usually uses an LCD (Liquid Crystal Display)

screen to display output from the computer. The LCD consists of several thin layers that polarize the light passing through them. The polarization of one layer, containing long thin molecules called liquid crystals, can be controlled electronically at each pixel, blocking varying amounts of the light to make a pixel lighter or darker. Other types of flat panel technology exist (such as plasma displays) but LCDs are most commonly used in computers, especially laptops.Older LCDs had slow response times and low contrast, but active matrix LCD screens have a transparent thin film transistor (TFT) controlling each pixel, so response, contrast, and viewing angle are much improved.

SPEACILISED MONITORSConnectivity

Most monitors connect to a PC via parallel ports. Parallel connectors use a male to connect to the PC and a female to connect to the device.Speed

The traditional output device of a person computer has been the CRT (Cathode Ray Tube) monitor. . CRT monitors are heavy and use more electrical power than flat panel displays, but they are preferred by some graphic artists for their accurate colour rendition, and preferred by some gamers for faster response to rapidly changing graphics.

PRINTERS

Having a printer is essential if the data you process with your computer is to be filed or distributed to others. Modern printers come in a variety of types, with many capabilities. One class is described as non-impact because the actual printing element never touches the paper. In the other class the print element does touch the paper, sometimes quite hard. Of course, it is named impact printing.

PRINTERSNon-impact Printers

Non-impact printers use a system where there is no mechanism used to strike a sheet of paper. Some specialized printers are ink

Impact PrintersAn impact printer forms characters and graphics on a

piece of paper by striking a mechanism against an inked ribbon that physically contacts the paper. These printers commonly produce near letter quality output, meaning it doesn’t produce high quality print outs. Companies usually uses impact printers for envelopes, mailing labels and invoices.

NON- IMPACT PRINTERS Laser printers

Laser printers are very fast, usually printing eight or more pages per minute. Laser printers can output both text and graphics, and this output can appear very close to professional printing quality. The dots making up the image are so closely spaced they look like characters typed on a typewriter. Most laser printers can print 600 dots per inch although printers with 1200 and 2400 dpi and more are common.

SpeedA laser printer for the home or small

office usually prints black and white texts at speed of 15 to 50 pages per minute. Colour laser printers print 4 to 24 pages per minute. Laser printers for large businesses print more than 150 pages per minute.

Laser Printer:

NON- IMPACT PRINTERS

Ink Jet PrinterInk jet printers create images

by shooting tiny droplets of ink at the paper. The aim of the spray is much more precise than the pins of a dot matrix printer, so the resolution of the image is far better. Colour ink-jet printers are able to create excellent colour images by combining red, green, blue and black ink. Ink-jet printers are usually used for printing on materials such as envelopes, labels, index cards and iron-on T-shirt transfers. For top quality images such as photos, you can use special coated paper to give an almost photo quality image.

SpeedThe speed of ink-jet printer is

measured by the number of pages per minute it can print. Most ink-jet printers print from 3 to 26 pages per minute. Graphics and colours print at a slower rate.

NON-IMPACT PRINTERS Plotters

These are sophisticated printers used to produce high-quality drawings such as blue-prints, maps and circuit diagrams. These printers are used in fields such as engineering and drafting. Current plotters use a row of charged wires to draw an electrostatic pattern on specially coated paper and then fuse toner to the pattern. It’s use of small dots enable it to provide high-quality output.

Plotters

IMPACT PRINTERS Dot- Matrix printers

When the ribbon presses against the paper, it creates dots that form characters and graphics. Most dot-matrix printers use continuous-form paper, in which thousands of sheets of paper are connected together. These pages have holes along the side that helps the paper to be fed into the printer. The quality of the graphics on the pages depends on the amount of pins the printer has; the more pins the sharper the graphics.

SpeedThe speed of a dot-matrix printer is

measured by the number of characters per second it can print. The speed of most dot-matrix printers ranges form 400 to 1100 characters per second.

Dot Matrix Printer:

IMPACT PRNTERS Line printers

A line printer is a high speed printer that prints an entire line at a time. Mainframes, midrange, servers, or networked applications, such as manufacturing, distribution, or shipping, often use line printers. These printers typically use 11-by-17 inch continuous-form paper. There are two types of line printers they are band printers and shuttle-matrix printers.

SpeedThe speed of a line printer is

measured by the number of lines per minute it can print. Some line printers print as many as 3, 000 liners per minute.

Line Printer:

PRINTERSConnectivity

Printers usually connect to a system unit by USB ports either at the back or front of the system unit.

SPEAKERS An audio output device is a component of

a computer that produces music, speech, or other sounds such as beeps. Two commonly used audio output devices are speakers and headsets. Most personal computers have a small internal speakers that usually emits only low-quality sound.

ConnectivityThe circuitry to produce sound

may be included on the motherboard, but high quality audio output from a PC usually requires a sound card in one of the expansion slots, connected to a set of good quality external speakers or headphones. Speakers can also be connected to the front of the system unit.

Speakers:

BIBLIOGRAPHY Thomas, E. Beach. PH.D. “Input and Output Devices”. 5

May 2006. www.la.umm.edu/~beach/terms/inputoutput.html/.

“A+ Study Guide: Domain 1.0 – Personal Computer Components – Input Devices”. 13 September 2008.http://www.mcmcsce.com/comptia/aplus/notes/aplus_input.shtml.

Gary Shelly B., et al. Discovering Computers 2006. Boston: Gary Shelly B., et al. Discovering Computers 2006. Boston: Shelly Cashman Series, 2005.Shelly Cashman Series, 2005.