1. Components of an Information System

2. Difference Between Hardware and Software
Physical equipment that makes up a computer system
If you can kick it or take an axe to it it is hardware.
Software:
Programs, routines and procedures (together with their associated documentation) which can be run on a computer system.
It is important not to confuse the media used to transport software with software itself
A CD is a piece of hardware which you can touch and kick and it may contain software which you cannot touch.
The CD is not software it is hardware

3. Examples of Hardware Hardware: Central Processor
Peripherals – these are hardware devices which are attached to the central processor:
They can be classified into four types:
Input:
Keyboard, Mouse, Scanner
Output:
Monitor, Speakers
Backing Storage:
Hard Disk, Floppy Disk Drive
Communications:
Modem

4. Standardisation
In general, hardware produced by one company will not be compatible with that produced by another
Hardware:
A POS terminal by IBM could not plug into an ICL system
Software:
A program written for the Mac would not run on a PC

5. Standardisation Software standardisation Advantages of Standardisation
Output may appear different:
E.g. web pages viewed on different systems
Different layout, resolution of images, etc.
Standardisation of file formats
Importing and exporting of data between applications
Advantages of Standardisation
Hardware and software will be known to be compatible
Choices from where to purchase equipment
Agreed standards for equipment – comeback if not up to standard
Disadvantages of standardisation
Less choice
Less competition amongst suppliers

6. Components of a Computer
Control Unit
This is the part of the central processor (CPU) which manages the execution of instructions. The control unit fetches each instruction in sequence, decodes and synchronises it before executing it by sending control signals to other parts of the computer.
Arithmetic and Logic Unit (ALU)
This is the part of the CPU where data is processed and manipulated. This consists of arithmetic and logic operations.
Random Access Memory (RAM)
Memory which holds data loaded from the backing store – data that the computer is to process, screen display etc.

7. Computer Performance Machine Cycle Number of Processors
A computer runs on a clock – a 2.5 GHz machine is running at 2.5 thousand million cycles per second. Each cycle is a clock pulse. The faster the clock, the more instructions per second.
The complexity of the instructions affects the speed of processing.
A program consisting of a larger number of simple instructions drawn from a reduced instruction set (RISC) may run faster than an equivalent program consisting of a smaller number of complex instructions drawn from an extended instruction set (CISC).
Number of Processors
A single processor can only run 1 instruction at a time. To get beyond this you need an additional processor. This allows more than one instruction to be run and increases the speed of the computer. Programs and computers have to be written to make use of the second processor.

8. Computer Performance (cont.)
Bus Speed
The speed of the computer is also determined by how fast the data can travel. Data travels down buses
Increasing the speed of the bus decreases the waiting time and increases the speed. The speed of the bus is determined by the clock speed
RAM
The more RAM you have, the more instructions you can store without having to access the disk which is slow. It decreases disk thrashing
Cache memory is even faster and with more of it, the machine runs faster still
Dedicated Processing Devices
Instead of using the processor to do all the processing you can use specialist processors to take some of the load and thus speed up the machine. These include sound and graphics processors

9. Making a Machine Run Faster
Hardware Options
Replace motherboard
Increases BUS speed
Processor
Add second/subsequent processor
Overclocking processor
Dedicated device
Dedicated processing device – sound card/graphics card, etc
RAM
Increase RAM – holds larger swap files/more data

10. Making a Machine Run Faster
Software Options
Defragment Hard Drive
Increases BUS speed
Remove Unused Programs
Frees up hard drive space
Large swap file
Memory Optimiser
Better use of memory
Replace programs with up to date ones
Make better use of memory and resources
Patch software / run anti virus / anti spyware
Remove programs using resources

11. Input Devices Examples include: Keyboard Numeric Keypad Joystick Mouse
Trackerball
Microphone
Touch Screen
Scanners
OCR
Digital Camera
Graphics Tablet
Digitiser
Push Switch
Sensor
ADC
Foot Mouse
Puff Suck Switch
Eye-Typer

12. Output Devices Loud Speaker Printer Examples include: Monitor Plotter
Buzzer
LED

13. Loud Speaker Used to give confirmation of actions
Can be used to read lines of text
Increased use with CDs and Music (MP3s)
Music technology requires specialist sound output devices.

14. LED and Buzzer LED Buzzers Can display the status of a device
FDD light displayed when in use
Lights on a Printer indicates status - on-line or off line for example.
Can be used to signal to hearing impaired people
Buzzers
Gives confirmatory actions
Set sounds to events in Windows
Bar Codes beep to indicate successful entry

15. Printers Three main types of printers: Choice of:
Impact Printers
InkJet Printers
Laser Printers
Choice of:
Colour
Black and White
Selection of different resolutions

16. Impact Printers Physical Connection between print head and paper Noisy
Slow (chain printers can be very fast)
Cheap to run
Colour or Black and White
Low Resolution
Can do Carbon Copies
Print on multi part paper

17. InkJet Printers
Ink is fired at the page and the number of DPI can be very high
High resolution
Colour or black and white
High running costs
Faster than a dot matrix but not as fast as laser
Can not print carbon copies

18. Laser Printers High Quality Images Fast Printing
Colour or Black and White (Colour is expensive)
Medium to low running costs
Excellent Quality
Need special transparencies to produce OHPs
Cannot do Carbon Copies

19. Monitor (VDU) Most common Output device
Range of Sizes – standard is 17”, but 21” or greater is available for specialists:
For example, designers
Newspapers and magazines
High quality output
Bulky, but LCD screens can reduce footprint size
More expensive than standard monitors
Less affected by glare
Fewer health issues compared to standard monitors
Possible health issues with standard VDU’s

20. Storage Devices Tape Hard Disk Floppy Disk Examples include:
CD ROM / R / RW
Other Storage Devices

21. Role of Storage Devices
To store data that is not currently being processed
Non volatile storage of programs and data
Sometimes referred to as secondary store or mass storage.

22. Tape Serial Access to data Used almost exclusively to hold backup data
Can hold in excess of 100Gb of data
Specialist devices required to read the tape
Slow access to data.

23. Hard Disk Sealed unit holding many GB of data
Fast direct access to the data.
Two types (standards):
SCSI (Small Computer Systems Interface)
High speed of transfer (historically – catching up)
Specialist card required – controller separate from device
Can daisy chain devices
MTBF (mean time between failures) greater on SCSI – reliability
IDE (Integrated Device Electronics)
Standard interface in PC’s (More common than SCSI)
Cheaper and slower than SCSI (catching up in speed)

24. Floppy Disk Floppy Disk Drive is standard on PCs
Portable between machines
Limited storage capacity (1.44 MB)
Slow access to data
Can be set to read only by use of a tag
Inexpensive
Constant use increases unreliability

25. CD ROM WORM (Write Once Read Many)
Holds 650 MB Data
Used for static data (data which does not change)
Encyclopaedias
Software Programs
RW CDs allow you to rewrite onto the CD.
This is only possible a limited number of times and requires specialist equipment. (approximately 1000)
DVD now available – Holds 12GB of data
Also RW DVDs
CDs/DVDs used to hold Music, Video, Pictures, etc.

26. Other Devices Zip disks (100 MB, 250 MB, 750MB etc)
Super Floppy Disk (120 MB)
Jazz Disks (1GB +)
Flash Memory (1 GB+)
All storage devices are pushing amount of storage they can hold
Figures constantly changing

27. Magnetic v Optical Devices
Disk or Tape
Can be reused many times
Very large storage capacity
Optical
CD Rom, DVD
RW CD ROMs/RW DVDs exist – limited life cycle
Limited storage capacity

28. Backup and Archive Backup Archive Considerations of Media:
Making copies of data or programs in case the originals are lost or corrupted.
Archive
The storage of information for long periods of time.
Removing the data from the original medium and transferring it to off line/secondary storage
Considerations of Media:
Speed of Backup (Direct or Serial) and speed of recovery
Amount of data (MB or GB)
Portability (Tapes, Removable disk)
Compatibility with other systems (CD, tape, etc)

29. Hardware Related to Use
Answers based on:
Portability
Specialist hardware required
Cost
Speed
Ease of use
Compatibility

30. Types of Software Operating Systems User Interfaces Utilities
Translation
Application
Programming Languages

31. Operating Systems
A program or suite of programs that control the entire operation of the computer.
Deals with the basic functions of the computer.
At a technical level, it handles the basic and central functions such as input and output operations and interrupts.
Examples include: MS-DOS, OS/2, UNIX, RISC-OS, Windows XP, LINUX, BeOS, etc.

32. User Interfaces
Methods by which the user can interface with the operating system/application
Command line
Dialog boxes
Menus
Windows

33. Utilities
Designed to perform a commonplace task, for example the transfer of data from one storage device to another, sorting a set of data, disk editor.
They are designed to make the operation of the computer easier.
Other examples: formatting programs, backup programs, anti-virus, etc.

34. Translation
Programs which convert a program from one language to another, for example from low level language to machine code.
This is the general name for three types of translators:
Assemblers
Compilers
Interpreters

35. Application Generic Tailor-Made Off-the-shelf Programming Languages
Cross over between categories:
Generic is off-the-shelf
Programming languages can be off-the-shelf and used to create tailor-made software

36. Generic
These are off-the-shelf packages which do not meet a specific purpose but serve a general purpose
For example:
Microsoft Office and components
Corel Suite
Lotus Suite
Word Processors, Spreadsheets, Databases
The software can then be customised to produce the result you want.

37. Tailor-Made Either: Or: Bespoke Customisation
The application is written for the purpose by a software house
Disads: Time consuming, expensive, limited support/books.
Ads: Fulfils purpose, individual support
Or:
Customisation
A generic application is customised using a programming language
Disads: Need to purchase the application and you get more than required.
Ads: Cheaper, lots of support.

38. Off-the-Shelf Purchasing solutions from a shop without alteration
For example:
SAGE payroll package
Heritage Library Database
The idea is to be able to open the package and run the software which delivers a specific solution
Can be generic (word processors)

39. Programming Languages
There are a variety of programming languages available.
Each language has a specific purpose
FORTRAN – Formula Translation
Mathematical and Scientific
COBOL – Common Business Orientated Language
Business, Data Processing
Languages can also be used to enhance the application:
Use of VBA to write macros, or write dll’s