Computer Applications NCBS Stage 1 Course Content

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 Slide 2 Computer Applications Stage 1

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 The Central Processing Unit Slide 3 Computer Applications Stage 1

Functions of a Computer • The function of a computer is to process data • Processing means turning data into meaningful information Input (Data in) Processing (Calculations etc) Output (Results of processing – Information) Storage of Results The Central Processing Unit Slide 4 Computer Applications Stage 1

Input • Data – Raw data is figures etc that can be manipulated • Programs – Instructions to the computer about what to do with the data The Central Processing Unit Slide 5 Computer Applications Stage 1

Input devices • Used to put data and programs into the computer – keyboard, disk, microphone, scanner etc The Central Processing Unit Slide 6 Computer Applications Stage 1

Processing Means turning raw data into meaningful information Logical Operations Mathematical Operations A=6 B=4 1+1=2 Logical deduction A>B The Central Processing Unit Slide 7 Computer Applications Stage 1

Processing • Takes place in the CPU • Main Memory holds the data and instructions that are being used • Processing needs both the CPU and Memory The Central Processing Unit Slide 8 CPU Memory Computer Applications Stage 1

Output • The results of processing need to be output for user to see and use The Central Processing Unit Slide 9 Computer Applications Stage 1

Output can be sent to …. • • Screen Disk (floppy, zip, CD, DVD etc) Printer To another computer via a network The Central Processing Unit Slide 10 Computer Applications Stage 1

The Parts of the CPU These parts make up the CPU Control Unit ALU Registers The Central Processing Unit Slide 11 • Control unit • Arithmetic/Logic Unit • Registers Computer Applications Stage 1

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 The Central Processing Unit Slide 12 Computer Applications Stage 1

The Arithmetic/Logic Unit (ALU)… • Performs either mathematical or logical operations – Addition, subtraction, multiplication etc – Greater than, less than etc • The ALU produces results The Central Processing Unit Slide 13 Computer Applications Stage 1

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 The Central Processing Unit Slide 14 Computer Applications Stage 1

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 The Central Processing Unit Slide 15 CPU Memory Computer Applications Stage 1

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 The Central Processing Unit Slide 16 Computer Applications Stage 1

Storage Devices • • The Central Processing Unit Disks CDs DVDs Paper Slide 17 Computer Applications Stage 1

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 The Central Processing Unit Slide 18 Computer Applications Stage 1

Programs • Programs are sets of instructions for the computer to follow • The program must be in Memory (RAM) before processing can take place The Central Processing Unit Slide 19 Computer Applications Stage 1

Executing/Running a Program The program must be placed in Main Memory The data must be placed in Main Memory The Central Processing Unit Slide 20 Computer Applications Stage 1

Running a Program Once the program and data are in place the following sequence is followed: 1. 2. 3. 4. Fetching Decoding Executing Storing The Central Processing Unit Slide 21 CPU Memory Computer Applications Stage 1

Fetching Instructions CONTROL UNIT ALU Registers The control unit fetches (gets) the instruction from memory. Memory The Central Processing Unit Slide 22 Computer Applications Stage 1

Decoding Instructions • The control unit decodes the instruction • It then moves the necessary data from Memory to the ALU for processing The Central Processing Unit Slide 23 CONTROL UNIT ALU Registers Memory Computer Applications Stage 1

Executing Arithmetic/Logic Operations The ALU performs the arithmetic or logical operation on the data All processing takes place in the ALU The Central Processing Unit Slide 24 Computer Applications Stage 1

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 The Central Processing Unit Slide 25 Control Unit ALU Registers MEMORY Computer Applications Stage 1

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 The Central Processing Unit Slide 26 Computer Applications Stage 1

(I-time) Instruction Time The time it takes the Control Unit to fetch an instruction from Memory and decode it is called instruction time Control Unit + ALU Memory The Central Processing Unit Control Unit Slide 27 Computer Applications Stage 1

(E-time) Execution Time The time it takes to carry out an ALU operation and then store the result is called execution time ALU + The Central Processing Unit Slide 28 Registers Memory Computer Applications Stage 1

Computer Speed • Computers carry out millions of instructions per second (MIPS) • Processors are described in Mega. Hertz (MHz) and Giga. Hertz (GHz) • These figures indicate how quickly the computer can process instructions The Central Processing Unit Slide 29 Computer Applications Stage 1

Conclusion and Key Words • • CPU ALU Registers Control Unit Main Memory RAM Data The Central Processing Unit • Information • Program • Secondary storage • Machine Cycle • I-time • E-time Slide 30 Computer Applications Stage 1

References 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 The Central Processing Unit Slide 31 Computer Applications Stage 1