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Computer Systems

Computer Systems can be viewed as a set of five cooperating subsystems: ... Tells the computer how to perform operations like input, output and storage ...

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Computer Systems

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  1. Computer Systems • A computer system is a combination of hardware and software , functioning together, processing data to achieve a purpose. • Computer Systems can be viewed as a set of five cooperating subsystems: • INPUTOUTPUTSTORAGEPROCESSCONTROL

  2. Computer Systems • A computer is an electronic device that accepts inputs, processes them and produces an output. • In processing, the computer follows out instructions • To carry out the instructions the following are needed: • Hardware • Software • Data • People • Procedures

  3. STORAGE OUTPUT INPUT PROCESS CONTROL

  4. Hardware Software Computer Systems Control Storage

  5. SOFTWARE • Software is a set of instructions that direct the hardware to perform certain tasks. • There are 3 types of software : • Systems Software • Utility Software • Applications Software

  6. Systems/Operating Software • Tells the computer how to perform operations like input, output and storage • Operating system-collection of programs used to organise files, communicate with peripheral devices and assist in the operation of the computer • The link between hardware and application software ( eg DOS, WINDOWS (95/98, XP)

  7. Utility Software • Specialised programs that perform 1 or a few basic tasks • Examples are virus checkers, spell checkers, clock , calculator,editors etc

  8. Applications Software • Designed to carry out a particular task, or to solve a user’s problem • allows computer to perform a wide range of tasks • Examples: Word processing packages • Spreadsheet packages ( E.g Excel) • Games

  9. INPUT –involves entering data into the computer. • This is a signal sent to the computer usually from the keyboard or mouse

  10. OUTPUT-involves the display of information to a person, data or another computer. • A signal sent from the computer to an attached device.

  11. STORAGE –involves the saving of a signal or a set of signals on a convenient medium

  12. PROCESS- carrying out a set of instructions, which occurs in the CPU. Changes data to produce information

  13. CONTROL –co ordinates the operations of the above. • Control is part of the CPU. It directs flow.

  14. Hardware • This is the machinery that makes up a computer system – the parts you can touch. • Hardware is classified into Peripheral Devices and Central Processor Devices

  15. Peripheral Devices • Peripherals are anything that you attach to a computer • These are associated with input, output and storage.

  16. Input/Output Devices • Interface between a system and its environment • They are classified according to speed, flexibility, convenience and cost

  17. Keyboard most common - QWERTY keyboard Mouse Scanner digitising - views a page and produces an image flatbed and hand held Other Devices digital camera video camera graphics tablet light pen barcode reader temperature sensor voice recognition equipment joystick INPUT DEVICES

  18. Printers Inkjet/Bubble jet Laser Monitor also called VDU - visual display unit display broken into a grid of pixels Laptops have a flat panel - LCD - liquid crystal display Other output devices speakers plotter sound card OUTPUT DEVICES

  19. The Central Processing Unit (CPU) • All processing takes place here • CPU is made up of millions of electrical circuits put into a silicon chip or integrated circuit • CPU is situated on the motherboard • CPU is measured in Megahertz(Mhz)

  20. Structure of CPU • CPU is made of 3 parts • Arithmetic Logic Unit (ALU) – performs arithmetic (=,-,x./) or logical operations on data. “Logical” includes comparing 2 items. • Registers –temporary storage locations for data currently being processed by the CPU • Control Unit – directs the flow of data and program instructions within the computer system. It controls movements of data between input, output, ALU and storage

  21. Buses – data travels throughout the motherboard on bus lines • Bus lines are soldered wire and appear silver.

  22. STORAGE

  23. People • People who work in the computer industry can be categorised as follows: • Design and Construction • Operations and Management • Users

  24. Design and Construction • These people plan and develop new computer systems or modify old systems.They include: • Systems analyst • Programmers • Engineers

  25. Operations and Maintenance • They keep the system working efficiently so that it achieves its purpose. They include: • Managers • Computer Operators • Data entry • Consultants • Technical support • Computer technicians

  26. Users • Users are people who are affected by computer systems. They include: • Direct Users • Indirect Users • Intermediary Users

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