1. Sir Thomas Boughey High School A/S Level ICT
Hardware
Sir Thomas Boughey High School
A/S Level ICT

2. Lesson Objectives Our Objectives:
To understand the nature, capabilities and limitations of hardware.
To understand the importance of data security and backup systems.

3. What is hardware
Hardware is the term used for the physical parts that make up a computer system.
Generally speaking, if you can actually ‘touch it’ then it is hardware.

4. Categories of hardware
Hardware is divided into five categories:
Input devices
Storage devices
Communication devices
Processing devices
Output devices

5. Hardware
Input devices
What goes in …

6. What are input devices
Input devices are used to get data from the outside world into the computer.
The ideal input device would operate automatically (I.e. without the need for people), and would also be fast, accurate and cheap.
Input devices include the following:
Scanners
OCR (Optical character recognition)
MICR (Magnetic ink character reader)
Digital cameras aswell as the keyboard & mouse

7. Input devices: capability
How the input device works
Scanner
(flatbed)
Reflected light is picked up by photo-sensitive cells and assembled into B&W or colour pictures e.g. web site building.
OCR
Text is scanned using special OCR software that recognises individual characters in the image e.g. utility bills.
MICR
Used to read characters written in magnetic ink e.g. banker’s cheques.
Digital camera
Used to capture images and store them digitally on a disk inside the camera.

8. Input devices: limitations
Possible limitations
Scanner
(flatbed)
If you cannot print in colour, there is little point in scanning in colour.
OCR
The accuracy of this software depends on the quality of the original text.
MICR
Expensive. Especially used by banks, because of the security that it provides.
Digital camera
More expensive than conventional cameras, but falling in price.

9. Hardware
Storage devices

10. What are storage devices
Storage devices are used to hold data separately from the PC’s hard disk drive. Data stored in this way can be retrieved later if required.
Floppy disks were originally used for backing up a disk drive, but the storage capacity of a modern PC has now made this an impractical option.
Alternative storage devices include the following:
CD-ROMs (Compact Disk- Read Only Memory)
CD-Rs (Compact Disk-Recordable)
CD-RWs (Compact Disk-ReWritable)
DVD (Digital Versatile Disk)

11. Storage devices: capability
How the storage device works
CD-ROMs
(read only)
Small plastic optical disks that typically store 700MB data (incl. Multimedia) using laser technology e.g. software.
CD-Rs
(write once)
Compact disks can hold 650MB. Data is written, and can be read by other PCs.
CD-RWs
(re-usable)
Used in a similar way to floppy disks, but holds up to 650MB.
DVD
(digital versatile)
Relatively new technology, developed in the 1990s. Holds 17GB – that’s around 25 CD-ROMS.

12. What are the drawbacks of these storage devices?
Try to think of one disadvantage for each storage device and write it down.
CD-ROMs (read only)
CD-Rs (write once)
CD-RWs (re-usable)
DVD (digital versatile)

13. Storage devices: limitations
Possible limitations
CD-ROMs
(read only)
Good for storage (high capacity) but data can only be read I.e. the disk cannot be used for recording.
CD-Rs
(write once)
As above, but can only be recorded once and never altered.
CD-RWs
(re-usable)
Data can be recorded, deleted and re-recorded, so subject to accidental error.
DVD
(digital versatile)
DVD-R (recordable) and DVD-RW (re-writable) are available, but capacity is reduced; still relatively expensive.

14. Communication devices
Hardware
Communication devices

15. What are communication devices
Communication devices are used to link computers together to share information and resources.
Many communication devices are used for networking.
Networking will be discussed in a separate session.
Communication devices include the following:
Modems
ISDN adaptors (Integrated Services Digital Network)

16. Communication devices
Modems:
Changes signals between digital and analogue form
Internal (cheaper-uses PC case / power) & external
Limited by modem speed, and the quality of the line
ISDN adaptors (Integrated Services Digital Network):
Digital signals used throughout the system
Data buffer ‘waiting room’ and ‘protocol converter’
Modem not required, but digital lines still expensive

17. Hardware
Processing devices

18. What are processing devices
The processor is the name given to the chip that performs all arithmetic and logic operations.
The processor includes all the hardware inside the case, excluding power supply and storage devices.
Processing devices include the following:
CPU (the central processing unit)
Mother board (holds all the built-in electronics)
Fast CPU clock speed = fast data processing
Measured in Megahertz (MHz) or Gigahertz (GHz)

19. Hardware
Output devices
Must come out!

20. Output devices include the monitor, printers, plotters and loudspeakers.
Try to think of three different types of printer and, for each one, write down:
(i) how it works,
(ii) one advantage, and
(iii) one disadvantage

21. Output devices Dot matrix printer:
Hammering pins against a ribbon onto the paper
Reasonable quality and cheap, but quite noisy
Ink-jet printer:
Squirt ink dots onto the paper to form letters
Quiet, cheap, good quality, B&W and colour
Laser printer:
Fastest and best quality, B&W and colour
Prices dropping but still expensive

22. Security of data & backup systems
Hardware
Security of data & backup systems

23. Deliberate destruction by disgruntled staff
Data security
There are many aspects to security of computerised systems. Can you think of some possible threats?
Theft of hardware
Deliberate destruction by disgruntled staff
Natural disaster
Hackers
Mistakes by operators
Virus attacks

24. The difference between security and privacy?
Making sure that hardware, software and data are protected from threat of harm
For example: theft, damage, hacking etc
Privacy:
Making sure that personal data is kept safe and not disclosed to anyone who is not entitled to see it
Covered by a piece of legislation called
the ‘Data Protection Act’

25. How to protect data integrity
Simple processes:
Data encryption (e.g. bank’s Electronic Funds Transfer)
Virus detection / repair (I.e. anti-virus toolkit software)
Also: physical security, and system access levels
Clerical procedures:
Passwords to access the network
Different access rights to data on the network
Write protect floppy disks (what about CD-RWs?)

26. Backup systems ‘Travelling back in time’ What are backup systems?
This is the regular and organised process of keeping copies of software and data. Backup systems enable any lost data to be recovered, should there be a partial or full system failure.
Why are backup systems important?
Lost data = lost trading power = lost profit = business failure
Periodic versus online backup?
Full backup I.e. all data files backed up once a week
Incremental backup I.e. data changed since last full backup
Online backup I.e. data written to several disks
simultaneously (esp. sales transactions)

27. Your Revision Tasks
Use textbooks and your notes to answer the set of A/S level examination questions on the following pages.

28. Textbooks ‘A’Level ICT – P.M.Heathcote
Understanding Information and Communication technology for AS level – Stephen Doyle
Information and Communication Technology for AS Level
– Julian Mott and Anne Leeming

29. Question One:
A company sells a range of health foods at five different shops. It also sells directly to the home from a number of vehicles. There are hundreds of different items of stock and many items are seasonal, so items in stock are constantly changing. Customers purchase goods and pay by cash, cheque or credit card.
The company is considering a computerised system to help manage sales and stock control. Bearing in mind the needs of this company what are the capabilities and limitations of possible
communication devices (4)
input devices (4)
output devices (4)
storage devices (4)
Based on a question from NEAB Paper

30. Question Two:
The owner of a small newsagents uses a computer to manage her orders and deliveries. Every week she copies the files onto a number of floppy disks and puts the disks into a drawer next to the computer.
State three problems that may be caused by this method of back-up. (3)
Describe a more appropriate back-up procedure. (6)
NEAB Paper

31. Question Three:
Modern personal computer systems usually include a floppy disk and a CD-ROM drive.
List three main differences between these two devices. (3)
i) Describe one example of an application for which floppy disks are used. (2)
ii) Describe one example of an application where a CD-ROM is used. (2)
NEAB Paper

32. Question Four:
Employees can often be responsible for causing loss or damage to their company’s data. Regular back-ups are taken by the company, but in order to prevent employees from causing such loss or damage, describe:
two measures that could be incorporated into the hardware used; (4)
two software features that could be used; (4)
two other procedures that the company could introduce. (4)
AQA ICT Module 2 Jan 2001

33. Question Five:
5. (a) Why is MICR used in preference to OCR in cheque processing systems? (1)
5. (b) Why is OCR used in preference to MICR in invoicing systems? (1)
5. (c ) (i) What is Optical Mark Reading (OMR)?
(ii) Give one situation where OMR might be used (2)
NEAB Paper

34. Chapters 14,15, 26 and 28 in Heathcote
Summary & What to do
Make sure you make a comprehensive set of notes on all areas discussed in this presentation.
Chapters 14,15, 26 and 28 in Heathcote

35. Thank you for watching Our original objectives were :
To understand the nature, capabilities and limitations of hardware
To understand the importance of data security and backup systems
Thank you for watching