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Computer Applications

Computer Applications. NCBS Stage 1. Course Content and Assessment. Practical – 60% (2 Hrs Weekly) File Management Internet Word Processing Spreadsheets Theory – 40% (I Hr Weekly). The Central Processing Unit. The ‘brain’ of the computer

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Computer Applications

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  1. Computer Applications NCBS Stage 1

  2. Course Content and Assessment • Practical – 60% (2 Hrs Weekly) • File Management • Internet • Word Processing • Spreadsheets • Theory – 40% (I Hr Weekly)

  3. The Central Processing Unit • The ‘brain’ of the computer • A tiny piece of silicon (chip) containing millions of transistors • Getting smaller, faster and cheaper all the time

  4. Functions of a Computer • The function of a computer is to process data • Processing means turning data into meaningful information Output (Results of processing – Information) Processing (Calculations etc) Input (Data in) Storage of Results

  5. Input • Data • Raw data is figures etc that can be manipulated • Programs • Instructions to the computer about what to do with the data

  6. Input devices • Used to put data and programs into the computer • keyboard, disk, microphone, scanner etc

  7. Processing Means turning raw data into meaningful information • Logical Operations • A=6 • B=4 • Logical deduction • A>B MathematicalOperations 1+1=2

  8. Processing • Takes place in the CPU • Main Memory holds the data and instructions that are being used • Processing needs both the CPU and Memory CPU Memory

  9. Output • The results of processing need to be output for user to see and use

  10. Output can be sent to …. • Screen • Disk (floppy, zip, CD, DVD etc) • Printer • To another computer via a network

  11. Control Unit Registers ALU The Parts of the CPU These parts make up the CPU • Control unit • Arithmetic/Logic Unit • Registers

  12. The Control Unit • This controls everything that happens inside the computer • It transfers data and program instructions between the Memory and the ALU • It sends the results back to Memory and later to a storage device

  13. The Arithmetic/Logic Unit (ALU)… • Performs either mathematical or logical operations • Addition, subtraction, multiplication etc • Greater than, less than etc • The ALU produces results

  14. Registers… • Are temporary storage areas for data and/or instructions • Data, instructions and results are held in registers for a very short time • They are faster than RAM so they speed up processing • Areas in the ALU and CU

  15. Main Memory • Main Memory is made up of RAM and ROM and is not part of the CPU • Data passes in and out of RAM to be processed CPU Memory

  16. Storage • Anything stored in RAM is only held there temporarily - until processing is complete • Permanent storage is called Secondary Storage • This is needed or work would be lost as soon as the computer was switched off

  17. Storage Devices • Disks • CDs • DVDs • Paper

  18. Memory v Storage • Memory or Main Memory is the term used for temporary storage ie RAM and is outside the CPU • Registers are a type of Main Memory found in the CPU • Secondary storage covers a lot of devices used for files such as disks, CDs etc

  19. Programs • Programs are sets of instructions for the computer to follow • The program must be in Memory (RAM) before processing can take place

  20. Executing/Running a Program • The program must be placed in Main Memory • The data must be placed in Main Memory

  21. CPU Memory Running a Program Once the program and data are in place the following sequence is followed: • Fetching • Decoding • Executing • Storing

  22. CONTROL UNIT ALU Registers Fetching Instructions The control unit fetches (gets) the instruction from memory. Memory

  23. CONTROL UNIT ALU Registers Decoding Instructions • The control unit decodes the instruction • It then moves the necessary data from Memory to the ALU for processing Memory

  24. Executing Arithmetic/Logic Operations • The ALU performs the arithmetic or logical operation on the data • All processing takes place in the ALU

  25. Control Unit ALU Registers Storing Results The ALU stores the result of its operation on the data in Memory or in a Register until they are output to a storage device MEMORY

  26. The Machine Cycle • This is the time taken by the CPU to process a single program instruction • The time is divided into 2 phases • I-time and • E-time

  27. Control Unit ALU Control Unit Memory Memory (I-time) Instruction Time The time it takes the Control Unit to fetch an instruction from Memory and decode it is called instruction time +

  28. ALU ALU Registers Memory (E-time) Execution Time The time it takes to carry out an ALU operation and then store the result is called execution time +

  29. Computer Speed • Computers carry out millions of instructions per second (MIPS) • Processors are described in MegaHertz (MHz) and GigaHertz (GHz) • These figures indicate how quickly the computer can process instructions

  30. CPU ALU Registers Control Unit Main Memory RAM Data Information Program Secondary storage Machine Cycle I-time E-time Conclusion and Key Words

  31. Computing Essentials 2005 By Timothy and Linda O’Leary Computers - Tools for an Information Age By H L Capron - Ch 3 Computing in the Information Age By Stern and Stern - Ch 4 References

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