TOPIC 2 ICT class notes for computer .pptx

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1. TOPIC 2 COMPUTER SYSTEM COMPONENTS

2. COMPUTER HARDWARE Hardware is the physical component of a computer system, the electrical parts and devices that make up a computer They are categorized according to five basic operation they performs; Input devices- we use to send data to computer processor/memory Processors- fetch, decode and execute data into information Memory – holds data/instructions that CPU needs Output devices – display information/results Secondary storage devices – store data/information for later use

3. SYSTEM UNIT It is a boxlike case that houses the computer’s main hardware components Inside the system unit there’s: Motherboard-large circuit board with thousands of electrical circuits Power supply – provides electric power of all parts of the system unit through main board Cooling fan – keeps the system unit cool Internal speaker – used for beeps when error is encountered Drive bays- housing for the computer’s hard drive, floppy drive and CD-ROM/DVD-ROM drives

4. MOTHERBOARD Microprocessor (CPU) – central processing unit interprets and caries out instructions given by the software Memory- enables the computer to retain information Chipset – a collection of chips that provide the switching circuitry needed to move data Input/output buses – pathways that allow the microprocessor to communicate with input and output devices

5. MICROPROCESSOR (CPU) The central processing unit, is the brain of the computer system Administrative section of computer Supervises the operations of the other units CPU is connected to all other parts of the computer Receives data and instructions given by user, processes accordingly and produces the output This section not only executes the instruction but also controls all the permanent or temporary storage of data, I/O activities as well as the function of different devices attached with it Its further dived into two Control unit (CU) 2. Arithmetic logic unit (ALU)

6. FOUR BASIC OPERATIONS OF CPU FETCH – the control unit takes the instruction that is stored in the main memory DECODE – the control unit translates the instructions into machine language or binary code EXECUTE – carryout the command STORE- write the result to memory

7. Memory

8. What are the types of memory Are of two types, namely; Volatile memory – (Random Access Memory/RAM; Cache Memory, virtual memory) – contents of memory are erased when power supply is turned off. Also called temporary storage Nonvolatile memory-(Read Only Memory/ROM; Flash memory)- contents of memory are NOT erased when power is turned off. Also called permanent storage

9. Cache memory vs virtual memory Cache memory – located within the CPU chip, it is the memory the microprocessor uses to store frequently used instructions and data Faster than RAM Virtual memory – part of the hard disk is reserved as RAM When RAM modules become full the CPU accesses the hard disk to store and retrieve data Slower than RAM

10. Starting and restarting a computer It is of two types of booting; Cold booting Warm booting Cold booting – when the computer is started after having been switched off. Warm booting – when the operating system alone is restarted (without being switched off) after a system crash or freeze

11. Boot process There are two boot processes Boot priority Boot failure Boot priority – the boot priority is the order in which these devices are search to find a valid bootable operating system Boot failure – boot failure means when you lose hard drive of your computer

12. The input and output devices INPUT DEVICES They are the devices that allow data to be input into the computer system. They include; Keyboard Mouse Touchpad Joystick Scanner Touchscreen Digital Camera Microphone, Graphics Tablet, Barcode Reader, Magnetic Stripe Card, Sensors etc

13. 1. KEYBOARD The ideal input devices that is used to input texts, numbers and instructions e.g CTRL+V into the computer Most keyboard have qwerty layout. Examples of keyboards include rollup keyboard, laser or infrared, ergonomic, gaming keyboard etc Keyboards have two connection types; USB type of connection Serial type of connection

14. Parts of a keyboard Special keys These keys work in combination with other keys. Some of the special keys include; Alt, Caps lock, shift, ctrl, window key etc 2. Alphabetic keys These are marked with the English alphabets from A to Z . There are 26 alphabetic keys 3. Numeric keys The keys marked with numbers from 0 to 9 are called number keys. They are also placed at the right side of the keyboard known as numeric keypad

15. 4. Cursor movement keys Used to move the cursor in four direction up, down, left, right. They are also called arrow keys Both tab key, space bar and arrow keys are used to move the cursor 5. Function keys The function keys are placed at the top row of the keyboard marked with F1 to F12 used to perform special functions

16. Other keys include; Tab key – allows cursor to jump five spaces forward Delete key- erase anything typed from the right side of the cursor Enter key – tell the computer that you have finished a word or line and brings the cursor down to the next line Shift key – used to type letters in capital or small case without using caps lock key, also used to type symbols printed on the top of the number keys Backspace key – delete characters to the left of the cursor Caps lock key – type in capital letters Space bar – creates space between words

17. 2. THE MOUSE A mouse is an external computer hardware device It allows a user to control the motion of a computer cursor It has the following parts Mouse wire Right button Left button Scroll wheel

18. Types of mouse Optical mouse – uses light emitting diode, an optical sensor, and a digital signal processing Wireless mouse – mouse without wire or cord GSTICK mouse – its pencil like mouse Trackball mouse – consists of a ball held by a socket containing sensors to detect a rotation of the ball

19. FUNCTIONS OF MOUSE Move mouse cursor Open or execute program Drag and drop Scrolling MOUSE SKILLS Single clicking – it can be either left click or right click Dragging – moving a folder/file by pressing and holding left button Right click – clicking on the right side of the mouse Scrolling – either using the mouse scroll wheel

20. 3. SCANNERS Device that optically scans images, printed text, handwriting or an object Converts it to a digital image Types of scanners include; flatbed scanner, slide scanner, handheld scanner Scanners scan a document as an image (this means you cannot edit it) Scan a document directly to a pdf file

21. 4. THE JOYSTICK It is an input device that has a stick the pivots on a base and reports its angle or direction to the device it is controlling such as an aircraft or video game It also has multiple buttons that can also communicate with the machine, such as the “a” button or “b” button that video games use for jumping, crouching, etc

22. 5. THE DIGITAL CAMERA A digital camera is an input device used to take video or still photographs, or both, digitally by recording images by an electronic image sensor

23. OUTPUT DEVICES Output devices are hardware devices that display or present information to the user or other people Output devices lets a computer to communicate with you The devices which are used to display the data to the user either in the form of hard copy or soft copy are called output devices

24. Examples of output devices Display devices Printer Speaker Headphone

25. 1. DISPLAY DEVICES They include Monitor cathode ray tube (CRT) LCD technology, TFT (thin film transistor), LCD (Liquid Crystal Display) i.e Flat-panel display and gas plasma

26. 1. MONITORS The monitors are display devices. Display is the most-used output device on a computer Display provides instant feedback by showing you text and graphic images as you work or play Common definitions Pixel- a pixel is a dot of color, the smallest part of a display Resolution- number of pixels on display area. It is expressed like height x weight Aspect ration – ratio between number of horizontal pixel and the number of vertical pixels

27. Color depth – number of bit that are used to describe a color. There are three components RGB i.e. red/green/blue DISPLAY TECHNOLOGIES There are many technologies available such as; Cathode ray tube (CRT) Liquid crystal display (LCD) Plasma Project NB: Only CRT and LCD are used in computer monitors (Plasma is used only in large screen size >40 inches)

28. 2. PRINTERS An output device that produces text and graphics on a physical medium such as paper or transparency film Hard copy printout Either print using landscape or portrait Print requirement varies Types of printers include; non-impact printer, ink jet printer, laser printer, thermal printer, plotters and large format printers, photo printer etc

29. Whenever you want to buy printer consider Budget Printer speed Color/black and white Cost of printing per page Print size of paper Whether a network printer or not

30. 3. Speaker Most Computers are fitted internal speakers although some may require external speakers Speakers helps producing beeping sound or any other sound from the computer

31. 4. Projectors Is a device that takes the text and images displaying on a computer or mobile Projects the images on a larger screen so that an audience can see the image clearly

32. Factors affecting hardware selection Define system capabilities Specify magnitude of the problem- how big the problem is Assess the competence the in house staff Develop time frame for the selection process Hardware and software to be considered as a package

33. COMPUTER HARDWARE SELECTION CRITERIA Hardware must support current software as well as software planned for procurement over the next planning Hardware must be compatible with existing or planned networks Hardware must be upgradeable and expandable to meet the needs of the next planning interval Hardware warranties must be of an appropriate length Hardware maintenance must be performed by [ local/remote vendor, in-house personnel ] Whenever feasible, hardware standards will dictate procurement of like brands and configurations to simplify installation and support Routine assessments of installed infrastructure will feed an upgrade/replace decision process

34. COMPUTER SOFTWARE Software is a set of computer programs, procedures and associated documents describing the program and how they are to be used Types of soft wares System software Application software

35. System software System software includes the operating system and all the utilities that enable the computer to function System software actually controls the hardware so that application software can perform any action or task Types of system software include; operating system Utilities Device drivers Language translators Compilers

36. Application software Application software include programs that do real work for user Examples include; payroll systems, inventory control, manage student database, word processor, spreadsheet, database management system etc Categories of application software; Business software Graphic and multimedia Home/personal/education Communication

37. Types of application software Presentation software Spreadsheet software Database software Multimedia software Word processing software etc Games

38. SOFTWARE SELECTION CRITERIA Software must be compatible with current and future hardware over the next planning interval Software maintenance and warranties must be of appropriate length and cost Software help desk must be maintained by [ vendor, third party, in-house personnel ] Software must be standardized throughout the business to improve purchasing power, simplify training, and facilitate support Software must comply with current standards set by technology leadership Software must support and enhance business goals

39. Functions of various computer software 1. Allocating system resources: The system resources are time, memory, input, and output. The time in the CPU is divided into time slices. The time slices is measured in terms of milliseconds. Based on the priority of tasks the time slices are assigned 2. Monitoring system activities: The system security and system performance is monitored by system software. System performance includes response time and CPU utilization. 

40. 3. File and disk management: The user needs to save, copy, delete, move and rename the files. The system software will handle those functions. Disk and file management is the technical task. 4. Managing Information 5. Manipulating Data 6. Constructing Visuals 7. Coordinating Resources 8. Calculating Figures

41. Storage devices They include Hard disk Floppy disks- CD ROMs DVDs Pen drives Blue ray disks