HardwareHardware

Learning ObjectivesLearning Objectives

Define the terms associated with computer hardware, describe how the elements of the system relate to one another and practise classification of devices.Discuss the meaning of data capture (to include images) using a range of both manual and automatic examples. Explain how the data captured can be entered onto a computer system.Describe a range of peripheral devices. For each identify features, advantages and disadvantages give a range of suitable applications for each device.Describe secondary storage in both magnetic and optical media explain the features of, advantages and disadvantages of each medium classify examples of data storage as magnetic or optical.

Hardware

The term hardware refers to the physical parts of a computer system.

Peripheral DevicesPeripheral Devices

Not part of the essential computer, i.e. the Not part of the essential computer, i.e. the memory and microprocessor.memory and microprocessor.

Input DevicesInput Devices

Input devicesInput devices allow us to tell the allow us to tell the computer what we want it to do and enter computer what we want it to do and enter raw data into a computer.raw data into a computer.

They provide a direct connection between They provide a direct connection between humans or the physical (or real) world and humans or the physical (or real) world and the microprocessor (CPU).the microprocessor (CPU).

Data EntryData Entry MethodsMethods

Automatic or Automatic or Manual?Manual? Many automatic input devices Many automatic input devices use only some use only some

of the available data and this is known as of the available data and this is known as samplingsampling..

Is data stored and then sent to the processor Is data stored and then sent to the processor after a set period of time or immediately sent after a set period of time or immediately sent to the processor?to the processor?

Which type of keyboard?Which type of keyboard?

Which type of keyboard?Which type of keyboard?

QWERTY keyboard - common keyboard.QWERTY keyboard - common keyboard. Prone to damage from dirt or liquids because of the Prone to damage from dirt or liquids because of the

gaps between the keys. gaps between the keys.

Touch-sensitive / Numeric keypad:Touch-sensitive / Numeric keypad: Fewer keys simplifies input required and leads to Fewer keys simplifies input required and leads to

fewer input mistakes.fewer input mistakes. Keys are touch sensitive.Keys are touch sensitive. Protected from elements / vandalism.Protected from elements / vandalism. Made of more resilient material because of volume of Made of more resilient material because of volume of

use.use.Musical keyboardMusical keyboard

Arranged like a piano keyboard and needs a MIDI (musical Arranged like a piano keyboard and needs a MIDI (musical instrument digital interface).instrument digital interface).

Which type of pointing device?Which type of pointing device?

Mouse or Trackerball / Touchpad / Glide Mouse or Trackerball / Touchpad / Glide padspads

Mouse used if a flat surface is available.Mouse used if a flat surface is available.

Barcode readersBarcode readers

A laser scanner reads the reflected laser light from a A laser scanner reads the reflected laser light from a series of dark and light coloured lines of varying thickness. series of dark and light coloured lines of varying thickness. The different widths of pairs of lines make up a code that The different widths of pairs of lines make up a code that can be converted into a number. can be converted into a number. This number can then be used as the key field relating to This number can then be used as the key field relating to a file of items that have been bar-coded. a file of items that have been bar-coded. Advantages:Advantages:

Faster data entry.Faster data entry. More accurate. More accurate.

Disadvantages:Disadvantages: Bar codes can be damaged.Bar codes can be damaged. Can be difficult to get the bar code reader into a position to read Can be difficult to get the bar code reader into a position to read

the bar code on large items.the bar code on large items.

ScannersScanners

Converts a document into a series of pixels Converts a document into a series of pixels (picture elements – these are small squares (picture elements – these are small squares that, when put together, form a picture). that, when put together, form a picture).

The larger the number of pixels, or conversely The larger the number of pixels, or conversely the smaller each individual pixel, the better the the smaller each individual pixel, the better the definition of the final picture. definition of the final picture.

Uses: Uses: Entering hard copy images into a computer.

Methods of Image CaptureMethods of Image Capture

Video capture cardVideo capture card

Allows the processor to store the values of Allows the processor to store the values of the screen pixels for a specific picture i.e. the screen pixels for a specific picture i.e. the action to be frozen. the action to be frozen.

Uses:Uses: E.g. A market stall that uses a video camera E.g. A market stall that uses a video camera

to take an image of a customer and then to to take an image of a customer and then to select one image to print onto a T shirt.select one image to print onto a T shirt.

Digital cameraDigital camera

Image is stored electronically enabling the Image is stored electronically enabling the user to download it into a computer and user to download it into a computer and manipulate the image and print out the manipulate the image and print out the images if desired.images if desired.

Image manipulation softwareImage manipulation software

Used to alter or edit images in any way Used to alter or edit images in any way that is required.that is required.

Graphics TabletGraphics Tablet

A flat surface on which a piece of paper is A flat surface on which a piece of paper is placed. placed.

The user can then draw on the paper and The user can then draw on the paper and the tablet will sense where the pencil is the tablet will sense where the pencil is pointing and transfer the line to the screen.pointing and transfer the line to the screen.

MicrophonesMicrophones

Used to input sound to a computer Used to input sound to a computer system.system.

One use is voice recognition, which is One use is voice recognition, which is rather unreliable, but is an attempt by the rather unreliable, but is an attempt by the computer to understand human computer to understand human communicationcommunication..

MICR MICR ((MMagnetic agnetic IInk nk CCharacter haracter RReader)eader)

Advantages:Advantages: Characters are readable by humans and by Characters are readable by humans and by

computers.computers. 100% accurate when read by computer. 100% accurate when read by computer.

Disadvantages:Disadvantages: Expensive to print in magnetic ink.Expensive to print in magnetic ink.

OCR OCR ((OOptical ptical CCharacter haracter RReader)eader)

Reads text directly from a document.Reads text directly from a document.Measures the light reflected to determines shape of Measures the light reflected to determines shape of characters.characters.Compares them with examples in memory.Compares them with examples in memory.Advantage:Advantage:

Automatic and fast data entry.Automatic and fast data entry.

Disadvantage:Disadvantage: UnreliableUnreliable

Uses:Uses: Reading post codes on printed documents.Reading post codes on printed documents. Reading documents for blind people, the contents of which can Reading documents for blind people, the contents of which can

be output using a voice synthesizer.be output using a voice synthesizer.

OMR OMR ((OOptical ptical MMark ark RReader)eader)

Can recognise the presence of a mark Can recognise the presence of a mark on a sheet of paper by light reflection.on a sheet of paper by light reflection.The position of the mark conveys The position of the mark conveys information to the machine.information to the machine.Printing is done using a special type of Printing is done using a special type of ink which the optical scanner does not ink which the optical scanner does not see. see. Advantage:Advantage:

Automatic and fast data entry.Automatic and fast data entry.

Disadvantage:Disadvantage: Cannot read paper if folded or dirty.Cannot read paper if folded or dirty. Restricted to multi choice questions.Restricted to multi choice questions.

Output DevicesOutput Devices

Show the results of the computer’s Show the results of the computer’s processing to the user in some form.processing to the user in some form.

Monitor screensMonitor screens

Colour or monochrome Colour or monochrome

Screen Resolution Screen Resolution (number of pixels on the (number of pixels on the screen)screen) > Pixels = Better picture> Pixels = Better picture What you need depends on the application.What you need depends on the application.

TouchscreenTouchscreen

Input and Output. Input and Output. Information is output by the system onto the screen and Information is output by the system onto the screen and the user is invited to answer questions or make choices the user is invited to answer questions or make choices by pointing at a particular area of the screen. by pointing at a particular area of the screen. The device senses where the user is pointing and can The device senses where the user is pointing and can report the position to the processor. report the position to the processor. The processor can then deduce what the user’s reply The processor can then deduce what the user’s reply Uses:Uses:

In areas where keyboards are not appropriate, e.g. where the In areas where keyboards are not appropriate, e.g. where the device may suffer from vandalism. device may suffer from vandalism.

For users who would find difficulty using other input devices, e.g. For users who would find difficulty using other input devices, e.g. very young children who want to be able to draw on a screen.very young children who want to be able to draw on a screen.

PrintersPrinters

Provides the user with an output from the Provides the user with an output from the system which is permanentsystem which is permanent i.e. hard copyi.e. hard copy

Dot MatrixDot Matrix

Pins strike at the surface of the paper.Pins strike at the surface of the paper. Advantages:Advantages: Possible to obtain multiple copies by using carbon Possible to obtain multiple copies by using carbon

paper or self carbonating paper.paper or self carbonating paper.

Disadvantages:Disadvantages: SlowSlow Poor qualityPoor quality Noisy Noisy Not possible to print in colour.Not possible to print in colour.

Use:Use: ReceiptsReceipts

Ink jet printersInk jet printers

Spray ink on to the paperSpray ink on to the paperAdvantages:Advantages:

Better quality and faster than dot matrix. Better quality and faster than dot matrix. Can be in colour.Can be in colour.

Disadvantages:Disadvantages: Cannot produce the two copies that a dot matrix can.Cannot produce the two copies that a dot matrix can. Need to change the colour cartridges often.Need to change the colour cartridges often. Cannot hold a lot of paper at one time.Cannot hold a lot of paper at one time. Less copies a minute than laser printers.Less copies a minute than laser printers.

Uses:Uses: Applications which require portability and low volume output Applications which require portability and low volume output

where changing cartridges is not an issue. e.g. Small offices and where changing cartridges is not an issue. e.g. Small offices and stand alone systems. stand alone systems.

Applications which require very high quality output and where Applications which require very high quality output and where speed is not an issue, e.g. Digital camera applications.speed is not an issue, e.g. Digital camera applications.

Laser printersLaser printers

Print in the same way as photocopiers. Print in the same way as photocopiers. Powdered ink, called 'Toner' is fused onto paper by heat Powdered ink, called 'Toner' is fused onto paper by heat and pressure. and pressure. Advantage:Advantage:

Print more copies a minute than a ink jet printer.Print more copies a minute than a ink jet printer. Ink lasts for longer so they don’t need to change the cartridges Ink lasts for longer so they don’t need to change the cartridges

so often.so often.

Disadvantage:Disadvantage: Expensive to purchase.Expensive to purchase. Bulky and heavy.Bulky and heavy.

Uses:Uses: Applications which require rapid, high quality and high volumes Applications which require rapid, high quality and high volumes

of output, e.g. Most offices and schools. of output, e.g. Most offices and schools.

Other types of printerOther types of printer

Also consider:Also consider: PlottersPlotters Braille printersBraille printers Black and white laser printersBlack and white laser printers Colour laser printersColour laser printers

Research these and find out more about Research these and find out more about them.them.

SpeakersSpeakers

Used to output sound from a computer Used to output sound from a computer system.system.

Actuator

Basically a motor. Instead of saying the “processor send a signal

to a motor to open an automatic door” we now say ““processor send a signal to an actuator to open an automatic door”.

Secondary Storage MediaSecondary Storage Media

Devices which or media used to keep Devices which or media used to keep information available for later use.information available for later use. i.e. outside the processor.i.e. outside the processor.

Types categorised according to:Types categorised according to: Means by which the data is stored:Means by which the data is stored:

Optical / MagneticOptical / Magnetic How data is stored?How data is stored?

Sequential / Direct AccessSequential / Direct Access CapacityCapacity Physical size / PortabilityPhysical size / Portability Access timeAccess time

MagneticMagnetic

Magnetic tapeMagnetic tape

Advantage:Advantage: Large storage capacity Large storage capacity Physically small so very portable.Physically small so very portable.

Disadvantage:Disadvantage: Sequential access – slow access time. Sequential access – slow access time.

Uses:Uses: Back upsBack ups Storage for batch processing.Storage for batch processing.

Floppy diskFloppy disk

Advantage:Advantage: Portable, many computers have a floppy disk drives Portable, many computers have a floppy disk drives

(although this is going out of fashion).(although this is going out of fashion). Cheap.Cheap.

Disadvantage:Disadvantage: Small storage capacity (~1.4Kb)Small storage capacity (~1.4Kb) Slow access times. Slow access times.

Uses:Uses: Small files to be moved from one computer to Small files to be moved from one computer to

another.another. Backup small data files.Backup small data files.

Zip / Jaz DiscsZip / Jaz Discs

Larger capacity than floppy disks.Larger capacity than floppy disks.

OpticalOptical

CD ROMCD ROMAdvantage:Advantage: Portable, many computers have a CD ROM drives.Portable, many computers have a CD ROM drives. Large storage capacity (~800Mb)Large storage capacity (~800Mb) Fast access timesFast access times Not alterableNot alterable

Disadvantage:Disadvantage: Slower access times and smaller storage capacity than a Slower access times and smaller storage capacity than a

hard disc.hard disc. Not alterable.Not alterable.

Uses:Uses: Applications which require the prevention of deletion of Applications which require the prevention of deletion of

data, accidental or otherwise. data, accidental or otherwise. Distributing software programs, data, music, Distributing software programs, data, music,

encyclopaedias, reference books etc…encyclopaedias, reference books etc…

CD RCD R

Advantage:Advantage: Portable, many computers have a CD ROM drives.Portable, many computers have a CD ROM drives. Large storage capacityLarge storage capacity Fast access timeFast access time Alterable (only once).Alterable (only once).

Disadvantage:Disadvantage: Slower access times and smaller storage capacity than a hard Slower access times and smaller storage capacity than a hard

disc.disc. Alterable.Alterable.

Uses:Uses: Applications which require a single ‘burning’ of data:Applications which require a single ‘burning’ of data: E.g.E.g.

recording of data for archiving or a one off backup.recording of data for archiving or a one off backup.recording of music downloads from the Internet.recording of music downloads from the Internet.recording of music from MP3 format.recording of music from MP3 format.

CD RWCD RW

Advantage:Advantage: Portable, many computers have a CD ROM drives.Portable, many computers have a CD ROM drives. Large storage capacityLarge storage capacity Fast access timeFast access time Alterable (as many times as you want).Alterable (as many times as you want).

Disadvantage:Disadvantage: Slower access times and smaller storage capacity Slower access times and smaller storage capacity

than a hard disc.than a hard disc. Alterable.Alterable.

Uses:Uses: Applications which require the updating of information Applications which require the updating of information

and ability to record over old data.and ability to record over old data.

DVD ROM, R and RWDVD ROM, R and RW

As with CDs but higher storage capacity As with CDs but higher storage capacity (~ 4.7GB)(~ 4.7GB)

Solid State

Memory Sticks

http://en.wikipedia.org/wiki/Memory_Stick

Memory Sticks

http://en.wikipedia.org/wiki/Memory_card

PlenaryPlenary

Describe a range of peripheral devices.

For each identify features, advantages and disadvantages give a range of suitable applications for each device.