Hardware

1. Hardware

2. Learning 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.

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

4. Peripheral Devices • Not part of the essential computer, i.e. the memory and microprocessor.

5. Input Devices • Input devices allow us to tell the computer what we want it to do and enter raw data into a computer. • They provide a direct connection between humans or the physical (or real) world and the microprocessor (CPU).

6. Data EntryMethods • Automatic or Manual? • Many automatic input devices use only some of the available data and this is known as sampling. • Is data stored and then sent to the processor after a set period of time or immediately sent to the processor?

7. Which type of keyboard?

8. Which type of keyboard? • QWERTY keyboard - common keyboard. • Prone to damage from dirt or liquids because of the gaps between the keys. • Touch-sensitive / Numeric keypad: • Fewer keys simplifies input required and leads to fewer input mistakes. • Keys are touch sensitive. • Protected from elements / vandalism. • Made of more resilient material because of volume of use. • Musical keyboard • Arranged like a piano keyboard and needs a MIDI (musical instrument digital interface).

9. Which type of pointing device? • Mouse or Trackerball / Touchpad / Glide pads • Mouse used if a flat surface is available.

10. Barcode readers • A laser scanner reads the reflected laser light from a series of dark and light coloured lines of varying thickness. • The different widths of pairs of lines make up a code that can be converted into a number. • This number can then be used as the key field relating to a file of items that have been bar-coded. • Advantages: • Faster data entry. • More accurate. • Disadvantages: • Bar codes can be damaged. • Can be difficult to get the bar code reader into a position to read the bar code on large items.

11. Scanners • Converts a document into a series of pixels (picture elements – these are small squares that, when put together, form a picture). • The larger the number of pixels, or conversely the smaller each individual pixel, the better the definition of the final picture. • Uses: • Entering hard copy images into a computer.

12. Methods of Image Capture

13. Video capture card • Allows the processor to store the values of the screen pixels for a specific picture i.e. the action to be frozen. • Uses: • E.g. A market stall that uses a video camera to take an image of a customer and then to select one image to print onto a T shirt.

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

15. Image manipulation software • Used to alter or edit images in any way that is required.

16. Graphics Tablet • A flat surface on which a piece of paper is placed. • The user can then draw on the paper and the tablet will sense where the pencil is pointing and transfer the line to the screen.

17. Microphones • Used to input sound to a computer system. • One use is voice recognition, which is rather unreliable, but is an attempt by the computer to understand human communication.

18. MICR (Magnetic Ink Character Reader) • Advantages: • Characters are readable by humans and by computers. • 100% accurate when read by computer. • Disadvantages: • Expensive to print in magnetic ink.

19. OCR (Optical Character Reader) • Reads text directly from a document. • Measures the light reflected to determines shape of characters. • Compares them with examples in memory. • Advantage: • Automatic and fast data entry. • Disadvantage: • Unreliable • Uses: • Reading post codes on printed documents. • Reading documents for blind people, the contents of which can be output using a voice synthesizer.

20. OMR (Optical Mark Reader) • Can recognise the presence of a mark on a sheet of paper by light reflection. • The position of the mark conveys information to the machine. • Printing is done using a special type of ink which the optical scanner does not see. • Advantage: • Automatic and fast data entry. • Disadvantage: • Cannot read paper if folded or dirty. • Restricted to multi choice questions.

21. Output Devices • Show the results of the computer’s processing to the user in some form.

22. Monitor screens • Colour or monochrome • Screen Resolution (number of pixels on the screen) • > Pixels = Better picture • What you need depends on the application.

23. Touchscreen • Input and Output. • Information is output by the system onto the screen and the user is invited to answer questions or make choices by pointing at a particular area of the screen. • The device senses where the user is pointing and can report the position to the processor. • The processor can then deduce what the user’s reply • Uses: • In areas where keyboards are not appropriate, e.g. where the device may suffer from vandalism. • 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.

24. Printers • Provides the user with an output from the system which is permanent • i.e. hard copy

25. Dot Matrix • Pins strike at the surface of the paper. • Advantages: • Possible to obtain multiple copies by using carbon paper or self carbonating paper. • Disadvantages: • Slow • Poor quality • Noisy • Not possible to print in colour. • Use: • Receipts

26. Ink jet printers • Spray ink on to the paper • Advantages: • Better quality and faster than dot matrix. • Can be in colour. • Disadvantages: • Cannot produce the two copies that a dot matrix can. • Need to change the colour cartridges often. • Cannot hold a lot of paper at one time. • Less copies a minute than laser printers. • Uses: • Applications which require portability and low volume output where changing cartridges is not an issue. e.g. Small offices and stand alone systems. • Applications which require very high quality output and where speed is not an issue, e.g. Digital camera applications.

27. Laser printers • Print in the same way as photocopiers. • Powdered ink, called 'Toner' is fused onto paper by heat and pressure. • Advantage: • Print more copies a minute than a ink jet printer. • Ink lasts for longer so they don’t need to change the cartridges so often. • Disadvantage: • Expensive to purchase. • Bulky and heavy. • Uses: • Applications which require rapid, high quality and high volumes of output, e.g. Most offices and schools.

28. Other types of printer • Also consider: • Plotters • Braille printers • Black and white laser printers • Colour laser printers • Research these and find out more about them.

29. Speakers • Used to output sound from a computer system.

30. 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”.

31. Secondary Storage Media • Devices which or media used to keep information available for later use. • i.e. outside the processor. • Types categorised according to: • Means by which the data is stored: • Optical / Magnetic • How data is stored? • Sequential / Direct Access • Capacity • Physical size / Portability • Access time

32. Magnetic

33. Magnetic tape • Advantage: • Large storage capacity • Physically small so very portable. • Disadvantage: • Sequential access – slow access time. • Uses: • Back ups • Storage for batch processing.

34. Floppy disk • Advantage: • Portable, many computers have a floppy disk drives (although this is going out of fashion). • Cheap. • Disadvantage: • Small storage capacity (~1.4Kb) • Slow access times. • Uses: • Small files to be moved from one computer to another. • Backup small data files.

35. Zip / Jaz Discs • Larger capacity than floppy disks.

36. Optical

37. CD ROM • Advantage: • Portable, many computers have a CD ROM drives. • Large storage capacity (~800Mb) • Fast access times • Not alterable • Disadvantage: • Slower access times and smaller storage capacity than a hard disc. • Not alterable. • Uses: • Applications which require the prevention of deletion of data, accidental or otherwise. • Distributing software programs, data, music, encyclopaedias, reference books etc…

38. CD R • Advantage: • Portable, many computers have a CD ROM drives. • Large storage capacity • Fast access time • Alterable (only once). • Disadvantage: • Slower access times and smaller storage capacity than a hard disc. • Alterable. • Uses: • Applications which require a single ‘burning’ of data: • E.g. • recording of data for archiving or a one off backup. • recording of music downloads from the Internet. • recording of music from MP3 format.

39. CD RW • Advantage: • Portable, many computers have a CD ROM drives. • Large storage capacity • Fast access time • Alterable (as many times as you want). • Disadvantage: • Slower access times and smaller storage capacity than a hard disc. • Alterable. • Uses: • Applications which require the updating of information and ability to record over old data.

40. DVD ROM, R and RW • As with CDs but higher storage capacity (~ 4.7GB)

41. Solid State

42. Memory Sticks • http://en.wikipedia.org/wiki/Memory_Stick

43. Memory Sticks • http://en.wikipedia.org/wiki/Memory_card

44. Plenary • Describe a range of peripheral devices. • For each identify features, advantages and disadvantages give a range of suitable applications for each device.