Components of an Information System

1. Components of an Information System

2. Difference Between Hardware and Software • Hardware: • 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 • 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 • 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:

12. Output Devices Examples include:

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 • 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: • 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 Examples include:

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 • Magnetic • 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 • 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: • Bespoke • 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