Computer Hardware Lect 3: Input / System Unit/Output & Storage 1
Input Devices: Giving Commands Input is any data or instructions that are entered into a computer. An input device is a type of hardware that gives users the ability to enter data and instructions into the computer s memory. 2
Input Devices: Giving Commands The keyboard, the most popular input device, enables data and instruction entry through the use of a variety of keys. 3
Input Devices: Giving Commands A pointer device controls an onscreen pointer s movements. A pointer is an onscreen symbol that signifes the command, input, or possible response. 4
Input Devices: Giving Commands The mouse is the most popular pointing device. A wheel mouse provides a wheel for easy vertical scrolling on documents or Web pages. 5
Input Devices: Giving Commands Mouse alternatives Trackball Pointing stick Touchpad or trackpad Joystick Touch screen Kiosk Stylus 6
Input Devices: Giving Commands Alternative specialized input devices include: Microphones for voice or speech recognition Scanner for optical character recognition (OCR) Bar code reader Optical mark reader (OMR) 7
Scanning Devices Magnetic-ink character recognition (MICR) Optical-character recognition (OCR). Optical-mark recognition (OMR) 8
Magnetic-ink character recognition (MICR) Human readable characters are printed on documents such as cheque using special magnetic ink. The cheque can be read using a special input unit, which can recognize magnetic ink characters, This method ensures accuracy of data entry and improves security. 9
Optical-character recognition (OCR). Optical-character recognition (OCR). An optical scanner is a device used to read an image, convert it into a set of 0's and 1's and store it in the computer's memory. The image may be hand-written document, a typed or a printed document or a picture 10
Optical-mark recognition (OMR) Special pre-printed forms are designed with boxes which can be marked with a dark pencil or ink. The document is read by a document reader, which transcribes the marks into electrical pulses. Applicable areas include: 1. Order forms containing a small choice of items. 2. Time sheets of factory employees in which start and stop times may be marked 3. Objective type answer papers in exams 11
System Unit 12
Introducing the System Unit System unit Case that contains the major hardware components of a computer Come in diferent styles Footprints Amount of space that the unit uses 13
Introducing the System Unit System unit (con t.) Some have embedded biometric authentication devices such as fngerprint readers, retina scanners, and face recognition systems to prevent unauthorized access. Form factor specifes how the internal components are located within the system unit. 14
Diferent System Units 15
Inside the System Unit 16
How Computers Represent Data Binary numbers Bit Only 0s and 1s Smallest piece of data a computer can work with Either on or of, a 0 or a 1 Eight bits byte a single unit of storage 17
How Computers Represent Data Data storage is in bytes Kilobyte (KB) one thousand bytes Megabyte (MB) one million bytes Gigabytes (GB) one billion bytes Terabyte (TB) one trillion bytes Modem s data transfer rate is in bits per second Example gigabits per second (Gbps) Characters Letters, numbers, and symbols converted into numbers the computer understands 18
What s on the Motherboard? Motherboard Printed circuit board that contains the electrical circuitry for the computer The majority of parts found on the motherboard are integrated circuits. Includes millions of transistors and carries electrical current A switch that is able to control the electrical signal fow to the circuit 19
What s on the Motherboard? Central processing unit (CPU) Integrated circuit chip that processes electronic signals Also known as a microprocessor or processor Is usually covered by a heat sink A heat-dissipating component that drains heat from the chip Instruction An operation performed by the CPU and assigned a specifc number Instruction set The list of CPU instructions for the operations 20
What s on the Motherboard? CPU (con t.) Control unit one of the two main parts Retrieves instructions from memory Interprets and performs those instructions Manages the machine cycle or processing cycle, the four-part process performed by the CPU Arithmetic logic unit (ALU) one of the two main parts Performs arithmetic and logical operations Involve adding, subtracting, multiplying, dividing Logical operations involve comparisons between two or more data items. 21
What s on the Motherboard? Machine cycle Instruction cycle Fetch: Retrieves program instructions Decode: Determines what the program is telling the computer to do Execution cycle: Execute: Performs the requested action Store: Stores the results to an internal register Registers store data when it must be temporarily stored in the CPU 22
What s on the Motherboard? 23
What s on the Motherboard? Factors that afect the performance of a CPU include: o Number of existing transistors o Data bus width and word size o Clock speed o Operations per microprocessor cycle o Use of parallel processing o Type of chip 24
What s on the Motherboard? Data bus Group of parallel wires that connect the CPU s internal components Width measured in bits Maximum number of bits the CPU can process at once is called the word size Determines which operating systems and software a CPU can run 25
What s on the Motherboard? System clock o o o o Electronic circuit that produces rapid pulses and coordinates the computer s internal activities. Clock speed measurement of the electrical pulses generated by the system clock, usually measured in gigahertz (GHz) Superscalar architecture enables the CPU to perform more than one instruction for each clock cycle Pipelining enables the CPU to process more than one instruction at a time improving performance 26
What s on the Motherboard? Memory Chips on the motherboard or within the CPU that retain instructions and data Random access memory (RAM) Temporarily stores data and instructions for the CPU Volatile contents erased after computer is shut of Allows CPU to access or store data and instructions quickly through RAM s memory address feature Identifes and locates stored data 27
What s on the Motherboard? Memory footprint Amount of RAM the operating system uses while it operates Virtual memory Section of the hard drive set aside to use when RAM gets full 28
What s on the Motherboard? Cache memory Small unit of ultrafast memory built into or near the processor Used to store frequently or recently access program instructions or data Faster than RAM More expensive than RAM 29
What s on the Motherboard? Read-only memory (ROM) Contains prerecorded instructions to start the computer Nonvolatile contents stored when CPU power of Basic input/output system (BIOS) First code run when the system is powered on Bootstrap loader Program locates and loads the operating system into RAM Complementary metal-oxide semiconductor (CMOS) Starts the power-on self-test and verifes other system components are operating correctly Power-on self-test (POST) Checks circuitry and RAM, marking defective locations 30
What s on the Outside of the Box? Outside a system unit? 31
Output Devices: Engaging Our Senses Output devices are computer hardware devices that give users the ability to see, hear, or feel the end result of processing operations. The two most popular output devices are monitors and printers. 32
Monitor Clarity Clarity: Monitor s clarity is indicated by it resolution, which is measured in pixels. Pixels are individual dots or picture elements that form images on a monitor. For the given monitor size, the greater the resolution (more pixel), the better the clarity of the image 33
A monitor s size Size: Monitor s size is by the diagonal of its viewing area. Common size are 15, 17, 19, 21 inches. The larger monitor have the advantage of displaying more information at one time, but they are expensive. 34
Output Devices: Engaging Our Senses Monitors display a temporary copy (soft copy) of processed data. Types of monitors include: Cathode-ray tube (CRT) monitors Liquid crystal display (LCD) monitors Active-matrix/thin flm transistor (TFT) monitors 35
Output Devices: Engaging Our Senses Cathode-ray tube monitors display colored output and are large in size. CRTs are usually used with older desktop computers. 36
Output Devices: Engaging Our Senses Liquid crystal display (LCD) monitors Also called fat-panel displays Thin Used on newer desktops and notebooks Growing in user popularity 37
Output Devices: Engaging Our Senses Active-matrix monitors Also known as thin flm transistor (TFT) technology Used for better on-screen color quality Other types of fat-panel displays include: Gas-plasma displays Field-emission displays 38
Output Devices: Engaging Our Senses A monitor s size is its diagonal measurement. This is straightforward for LCDs but more complex for CRTs. Quoted size is the size of the screen. Viewable area is the area that is unobstructed by the housing. Both must be disclosed by the manufacturer. 39
Output Devices: Engaging Our Senses Printers supply a hard copy of output displayed on a computer s monitor. Types of printers include: Inkjet printers Laser printers Dot-matrix printers Thermal-transfer printers Photo printers Plotters 40
Output Devices: Engaging Our Senses Inkjet printers Popular with home users and provide excellent images made up of small dots Advantages: Inexpensive Generate professional color output Disadvantages: Relatively slow Require expensive cartridges 41
Output Devices: Engaging Our Senses Laser printers Use electrostatic reproductive technology to produce high-quality output Advantages: Print faster than inkjet printers Black-and-white printing costs less per page than inkjet printers Disadvantages: Color laser printers are still more expensive 42
Output Devices: Engaging Our Senses Dot-matrix printers (impact printers) Older, less popular printers Used mostly for printing multipart forms and backup copies Advantage: Able to print 3,000 lines per minute Disadvantage: Poor print quality Noisy 43
Output Devices: Engaging Our Senses Thermal-transfer printer Used for industrial applications Uses a heat process to place color inks on paper Advantage: High-quality images Difcult to distinguish from photos Disadvantages: Expensive Slow 44
Output Devices: Engaging Our Senses Other output devices include: Speakers LCD projectors DLP (digital lightprocessing) projectors Multifunction devices 45
Storage: Holding Data for Future Use Storage is the process of saving software and data. Storage is also called mass storage or auxiliary storage. 46
Storage: Holding Data for Future Use Storage is dependent on two parts: A storage device, which has the ability to save data even when the user turns the power of Storage media that run on storage devices: Hard disks Floppy disks Flash memory CDs and DVDs 47
Storage: Holding Data for Future Use A hard disk drive (hard disk) High capacity High speed Considered secondary storage (online or fxed storage), compared with RAM, which is categorized as primary storage. 48
Storage: Holding Data for Future Use Hard disk drives Are random access storage devices and permit direct retrieval of desired data Contain a coating of magnetic material used for data storage. 49
Storage: Holding Data for Future Use Hard disks record data on concentric bands called tracks. Tracks are divided into sectors. A group of two or more sectors is a cluster. 50
Storage: Holding Data for Future Use 51
Storage: Holding Data for Future Use To keep track of fles, a table of the fle name and its location is stored on the disk by the computer s operating system. The fle allocation table (FAT) is the table created by older versions of Microsoft Windows. The new technology fle system (NTFS) is the present system used for tracking fle locations. 52
Storage: Holding Data for Future Use A portion of a hard disk set aside as if it were a physically separate disk is a partition. Partitions are often used to house diferent operating systems. Having partitions for diferent operating systems allows users to interact with programs developed in either system. 53
Storage: Holding Data for Future Use Disk cache A type of RAM CPU looks in disk cache frst Can speed up data retrieval 54
Storage: Holding Data for Future Use USB fash drive Known as Memory stick Thumb drive Jump drive Is a popular portable or removable storage device Replaced legacy technology of foppy disks and iip disks 55
Storage: Holding Data for Future Use CD-ROM or DVD-ROM (compact or digital video disc read-only memory) Data can be read but not altered. CD drive and DVD drive Optical storage devices Use laser beams to store data through: Pits, the indentations, a binary 0 Lands, the fat refective areas, a binary 1 56
What You ve Learned??? 57