Elements of a Computer System

1. Elements of a Computer System Dr Kathryn Merrick Thursday 4th June, 2009

3. Overview • Elements of a computer system: • Hardware • Software • People • Procedures

4. 1. Hardware Components • In order for a computer to do useful work it must have: • Input devices • Processing devices • Storage • Output devices

5. Mouse and Keyboard

6. Vision and Sound

7. Specialised Input Devices Wii Joystick Force feedback steering wheel and pedals Haptics devices

8. Central Processing Unit • Heart of Computer: • Fetches program instructions from memory • Performs operation • Writes result back into memory • Consists of a number of components • Registers where variables are stored • Arithmetic/Logic Unit (ALU) • Clock speed measured in GHz gives an indication of the power of the CPU

9. Graphics Processing Unit • Do computations related to • 3D graphics • 2D acceleration • Frame buffering • At least as powerful as the CPU • Can be in video card or integrated directly into motherboard

10. Primary Storage • Memory is essential to store: • The instructions of a program that is executing • The data upon which the program acts • Two main types: • Random Access Memory (RAM) • Read Only Memory (ROM)

11. Random Access Memory • Main memory of the computer • Small amount of fast memory used as a cache • Can be read from and written to • Volatile • When the power is turned off its contents are lost • Different speeds: faster is more expensive.

12. Read Only Memory • Cannot be written to by user • Non-volatile • Burned in at time of manufacture • Used to hold the boot code or bios code

13. Secondary Storage Equipment Old school floppies: storage in kB • CD: 600M capacity • DVD: 5-9G Gig capacity Tape drive: used for archival storage up to 20 Gig (cheap and stable) Flash memory capacity up to 32 Gig Plug and play, quick and convenient Hard disk drive: 80-300 Gig capacity

14. Output Devices

15. Communication Devices • Computers need a way to communicate with other computers • Typical communication alternatives • Local area network • Wireless network • Bluetooth • Infra-red

16. 2. Software • Operating system software • Manages system resources • Generic software • Word processors, spread-sheets… • Specialised software • Programming environments, 3D modelling, organisation specific software…

17. Operating Systems • Manages sharing of system resources between processes • Memory allocation • Prioritising resource access • Controls input and output • Facilitates computer networking • File system management • Provides programmers with an interface to access resources

18. June, 2008 Market Share Windows 90.89% Mac 7.94% Linux 0.8% Solaris 0.01% Other 0.36%

19. 3. People • Commercial computer systems often require a number of professionals to ensure the smooth running of the system: • System Administrator • Systems Analyst • Programmer

20. Systems Analyst • Help people and organisations solve their problems by identifying the role a computer system can play. • Identify what is possible and how a new system will work. • Gather system requirements • Develop models for a new system

21. System Administrator • Responsible for maintaining computer systems across an organisation: • Initial machine configuration • Creating user accounts • Granting network access • Fixing problems

22. 4. Procedures • Hardware: how often are computers upgraded or replaced? • Application software: when are new versions purchased? • Backup routine: how often? where are copies kept? • Anti-virus software: how is is renewed? • Security: who has access to servers? • Passwords: how many letters / numbers?

23. Summary • After this lecture you should be able to describe and give examples of: • Elements of a computer system: • Hardware, • Software • People, • Procedures • Main hardware components of a computer: • Input • Output • Processing • Storage