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ITMA02 Inside Computer


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ITMA02 Inside Computer

  1. 1. What You Will Learn . . . ITMA Lecture 02 Understand how computers represent data Understand the measurements used to describe data transfer rates and data storage capacity List the components inside the system unit Inside the Computer List the components on the motherboard How a CPU processes data Krates Ng 1 2 What You Will Learn . . . A Bit of Computer History Factors that determine a microprocessors • ENIAC in 1946 performance The types and purpose of memory in a computer 5,000 operations per sec. system y 1,000 sq. 1 000 sq feet The physical connectors on the exterior of the system I/O: cards, lights, unit switches 3 4 (cont’) Vacuum Tube or Valve • First commercial computer: UNIVAC I in 1951 1,905 operations/sec. 943 cubic feet I/O: magnetic tapes, printer Cost: US$750,000 5 6 1 K.Ng Sept08
  2. 2. (cont’) The Birth of Apple • IBM Personal Computer XT in 1981 • Apple I in 1976 CPU: 6502 at 1MHz RAM: 4KB Standard, expandable to 8KB or 48KB Graphics: 40x20 characters p Cost: US$666.66 7 from 8 Apple ][ Macintosh – the Birth of GUI Introduced in 1977 Introduced in 1984 CPU: 6502 at 1MHz, 8-bit CPU: Motorola MC68000 at 8MHz, 16 bits RAM: start from 4KB ROM: 64KB RAM: 128KB max. ROM: 12KB 3.5” 400KB floppy drive Cost: US$1,298.00 Weight: 16 lbs. Cost: US$2,495.00 Apple Macintosh commercial aired during 1984 Superbowl 9 10 Miniaturization For More…. History on computers and technology History on the Apple computers y pp p Transistors Integrated Circuits 11 12 2 K.Ng Sept08
  3. 3. Describing Hardware Performance How Computers Represent Data OFF ON OFF ON Hardware performance refers to the amount of data a OR = 1 bit computer can store and how fast it can process the 0 1 data = 1 Byte OR 0 0 1 1 0 1 0 0 System Case Socket 478 80 GB = 1 Byte Intel Pentium 4 ATX 7200 RPM 0 1 0 0 0 0 0 1 2.4Ghz Processor Motherboard Hard Drive Bit (Binary digit) – On or off state of electric current; considered the basic unit of information; represented by 1s and 0s (binary numbers) Byte – Eight bits grouped together to represent a character (an 512 MB alphabetical letter, a number, or a punctuation symbol); 256 DDR SDRAM different combinations Memory Module 13 14 Bits Bytes 1000 bits = 1 kilobit (kb) 8 bits = 1 Byte 1,000,000 bits = 1 megabit (mb) 1024 Bytes = 1 Kilobyte (KB) 1,000,000,000 bits = 1 gigabit (gb) 1,048,576 Bytes = 1 Megabyte (MB) 1,073,741,824 Bytes = 1 Gigabyte (GB) 1,099,511,627,776 1 099 511 627 776 Bytes = 1 Terabyte (TB) Kilobits per second (Kbps), megabits per second (Mbps), and gigabits per second (Gbps) are terms Kilobyte, megabyte, gigabyte, and terabyte are that describe units of data used in measuring data transfer rates terms that describe large units of data used in Example: 56 Kbps modem measuring data storage Example: 20 GB hard drive 15 16 Representing Characters: Character Codes Example Character codes translate numerical data into characters readable by humans Convert 13,467,823 bytes into MB American Standard Code for Information Interchange (ASCII) – Eight bits equals one character; used by minicomputers and personal computers 1. 13,467,823/1024 = 13152.2 KB Extended Binary Coded Decimal Interchange Code ( ) g (EBCDIC) – Eight bits equals one character; used by mainframe q ; y computers 2. 13,152.2 KB/1024 = 12.84 MB Unicode – Sixteen bits equals one character; over 65,000 combinations; used for foreign language symbols ASCII =4 0 0 1 1 0 1 0 0 EBCDIC =4 1 1 1 1 0 1 0 0 17 18 3 K.Ng Sept08
  4. 4. The System Unit ASCII and EBCDIC Code The system unit is a boxlike case that houses the computer’s main hardware components A footprint is the space taken up on the desk by the computer Form factor refers to the way the internal components are mounted in the unit 19 20 Types of System Units Inside the System Unit Desktop Notebook Motherboard (mainboard) – Large printed circuit board with thousands of electrical circuits Power supply – Transforms alternating current (AC) from wall outlets to direct current (DC) needed by the computer Cooling fan – Keeps the system unit cool Internal Speaker – Used for beeps when errors are encountered Drive bays – Housing for the Personal Digital computer’s hard drive, floppy drive, Assistant and CD-ROM / DVD-ROM drives 21 22 The Motherboard The Central Processing Unit: The Microprocessor The motherboard provides the centralized connection point for the computer’s components Most components are integrated circuits (chips) Chips carry electrical current and contain electronic CPU switches or transistors CPU socket Central processing unit (CPU) – A microprocessor that interprets and carries out instructions given by software. It controls the computer’s components 23 24 4 K.Ng Sept08
  5. 5. Components of the CPU Intel P4 (1) Control unit – Coordinates and controls all parts of the computer system Arithmetic-logic unit – Performs arithmetic or logical operations Registers – Temporarily store the most frequently used instructions and data 25 26 Intel P4 (2) Moore’s Law In 1965, Gordon Moore said “The complexity for min. component costs has increased at a rate of roughly a factor of two per year…” 27 28 The Control Unit The Arithmetic-Logic Unit The control unit manages four basic operations (fetch, decode, execute, and write-back) The four-step process is known as the machine cycle or processing cycle The arithmetic-logic unit (ALU) performs basic The processing cycle consists of two phases: arithmetic and logic operations Instruction Cycle Adds, subtracts, multiplies, and divides – Fetch – Gets the next program instruction from the computer s computer’s memory Compares alphanumeric data – Decode – Figures out what the program is telling the computer to do Execution Cycle – Execute – Performs the requested action – Write-back (Store) – Writes (stores) the results to a register or to memory 29 30 5 K.Ng Sept08
  6. 6. Microprocessor Performance Microprocessor Performance Data bus width – The number of pathways within Operations per cycle (clock speed) – The number of the CPU that transfer data; they are measured in bits clock cycles per second measured in megahertz (MHz) (8, 16, 32, or 64) or gigahertz (GHz) Word size – The maximum number of bits of data Superscalar operations – Carrying out more than one that the CPU can process at one time (8 bits, 16 bits, bits bits instruction per clock cycle 32 bits, or 64 bits) Pipelining operations – Feeding a new instruction into System Clock – electronic circuit that generates the CPU at every step of the processing cycle pulses at a rapid rate and synchronizes the computers internal activities 31 32 Parallel Processing Popular CPUs Intel Advanced Parallel processing involves using more than one CPU to Micro Devices Pentium MMX improve performance Pentium IV (AMD) Complex instruction set computer (CISC) – A chip that includes special-purpose circuits that carry out instructions at high speeds Pentium III Reduced instruction set computer (RISC) – A chip with a bare-bones instruction set that results in a faster processing Cyrix Motorola (Apple) speed than CISC chips 33 34 The Chipset Input/Output Bus PCI slots The input/output bus provides a pathway so that the microprocessor can communicate with input/output devices An input/output bus contains expansion slots which hold expansion cards PCI (Personal Computer Interface) slots are receptacles in A chipset is a collection of chips that provide the which expansion cards are switching circuitry needed to move data throughout the inserted. They support Plug and computer Play (PnP) devices. Expansion Card 35 36 6 K.Ng Sept08
  7. 7. Memory Virtual Memory Read-Only FULL Memory (ROM) Random Access Memory (RAM) Flash Memory Virtual memory: Part of the hard disk is reserved as RAM Memory is the term used to describe devices that enable the When RAM modules become full, the CPU accesses the computer to retain information. Program instructions and data hard disk to store and retrieve data are stored in memory chips for quick access by the CPU. Virtual memory is slower than RAM 37 38 Random Access Memory (RAM) Types of RAM Dynamic RAM (DRAM) – A memory chip that needs to be refreshed periodically or it will lose its data Synchronous DRAM (SDRAM) is synchronized with the computer’s system clock RAM is a type of memory that stores information temporarily Rambus DRAM (RDRAM) uses a fast bus to send and so that it’s available to the CPU receive data within one clock cycle. It is faster than RAM is volatile; the memory’s contents are erased when the SDRAM power is turned off Double data rate SDRAM (DDR SDRAM) is a type of Each byte of memory has a unique location or memory SDRAM that can send and receive data within one clock address cycle 39 40 Processing a Word Cache Memory CLICK ONCE TO BEGIN ANIMATION MONITOR WE B RAM KEYBOARD W E B B P i h (Level Primary cache (L l 1 or L1) – L Located within the CPU d i hi h E chip, it is the memory that the microprocessor uses to store W frequently used instructions and data Secondary cache (Level 2 or L2; Backside Cache) – Located near the CPU, it is the memory between the CPU and RAM CPU Cache memory is faster than RAM 41 42 7 K.Ng Sept08
  8. 8. Outside the System Unit Types of Connectors Point and click on a connector below to view information about it. Click again to remove the text. Drive bays On/off switch Reset button BACK Indicator lights FRONT The front panel contains drive bays, various buttons, and indicator lights VGA port (keyboard flows–throughspeed access for cardto be Sound – A Data port) Also called to to connect – connector high serial port to after Game port Data flows a – Allows pulses, monitorsmouse. transfer Parallelcard connectors Special serialjacks, allowing thekeyboard. Universal (mouse A 15 –infor serieseightport127 devicesanother oneof PS/2 connector – port) pin–connector used foroneconnectconnectorsbit Serial portSerial Bus (USB)Specialof upwiressound graphics-intensive Connectors and ports are physical receptacles located eight bits slowmini-plugs. Microphone, than serial ports. connected at a data transfer rate. fasterline-in, line-out, and speaker accept stereo time. interaction. at a time; of data simultaneously; on the back to connect peripheral devices to the connectors are plugged into the card. computer 43 44 Other Types of Connectors Additional Ports and Connectors Small computer system interface (SCSI) port – A Telephone – modem interface parallel interface that enables up to eight devices to Network – larger than telephone jack be connected to it PC card slot – notebook computers have slot for PC 1394 (FireWire) port – A high-speed connection for cards up to 63 devices p Sound card connectors – Infrared Data Association (IrDa) port – Infrared Mic – microphone input Line In – input from audio devices signals are used to communicate between peripheral Line Out – output to another audio device devices and the system unit Speaker – output to external speakers TV/sound capture – turns computer into a TV tuner 45 46 Summary Summary (continued) • The basic unit of information is the bit • The CPU’s performance is measured by the data bus width, • Large units of data are called kilobytes (KB), megabytes (MB), operations per second, speed, and cache memory gigabytes (GB), and terabytes (TB) • The system unit contains the motherboard, which is a circuit • Random access memory (RAM) is the computer’s main memory. board that provides receptacles for chips and input/output buses It is volatile. • The central processing unit (CPU) contains the control unit (CU) • There are various types of RAM including dynamic RAM RAM, and the arithmetic-logic unit (ALU). It manages the four basic (DRAM), synchronous DRAM (SDRAM), Rambus DRAM operations (fetch, decode, execute, and write-back). (RDRAM), and double data rate (DDR) SDRAM • The CPU processes data in a four-step cycle called a machine • Computers have ports such as serial ports, parallel ports, SCSI cycle. The CU manages four basic operations: fetch, decode, ports, USB ports, FireWire ports, and IrDA ports to connect execute, and store. input/output devices 47 48 8 K.Ng Sept08
  9. 9. What You Will Learn About The purpose of special keys and the most frequently used pointing devices The characteristics of a monitor’s quality and the various types of monitors Input/Output and Storage The two major types of printers The difference between memory and storage 49 50 What You Will Learn About Input Input is any data entered into the computer’s The categories of storage devices memory The performance characteristics of hard drives How data is stored on both hard and floppy disks The various optical storage media available for personal computers 51 52 Input Devices: Giving Commands Keyboard Keyboard Mouse Other Pointing The keyboard allows the computer user to enter Devices words, numbers, punctuation, symbols, and special function commands into the computer’s memory 53 54 9 K.Ng Sept08
  10. 10. Types of Keyboards The Mouse Enhanced / Extended Keyboard Wireless Ergonomic Keyboard Ergonomic Keyboard Enhanced or Extended keyboard – Typically 101 keys The mouse is the most widely used pointing device laid out in the QWERTY fashion; connected to the computer by a cable A mouse is palm sized Cordless keyboard – Uses infrared or radio wave signals As the mouse is moved, its movements are mirrored by the on- Ergonomic keyboard – Designed to help prevent screen pointer Repetitive Strain Injury, or RSI 55 56 Types of Mice Other Types of Pointing Devices Wheel Cordless Mouse Mouse Touch Trackball Screen Pointing Joystick Stick Sti k Wheel mouse – Contains a rotating wheel used to scroll vertically within a text document; connects to PS/2 port or USB port Tablet Cordless mouse – Uses infrared signals/RF/Bluetooth to Touch Pad Pen connect to the computer. 57 58 Using the Mouse Audio Input: Speech Recognition Speech recognition is a type Mouse buttons enable the user to initiate actions of input in which the computer recognizes words Clicking (left-, right-, or double-clicking) allows the spoken into a microphone user to select an item on the screen or open a program or dialog box Special software and a microphone are required i h i d Click and drag – Holding down the left mouse button and moving the mouse enables the user to move Latest technology uses continuous speech recognition objects on the screen where the user does not have to pause between words 59 60 10 K.Ng Sept08
  11. 11. Alternative Input Devices Monitors Scanners CRT LCD Flatbed Barcode reader A monitor is a peripheral device which displays computer output on a screen Screen output is referred to as soft copy Types of monitors: Cathode-ray tube (CRT) Liquid Crystal Display (LCD or flat-panel) 61 62 Cathode-ray tube (CRT) Liquid Crystal Display (LCD) Cells sandwiched between two transparent layers form images Resemble televisions Used for notebook computers, PDAs, cellular phones, Use picture tube technology and personal computers Less expensive than a LCD p More expensive than a CRT monitor monitor Take up more desk space and Take up less desk space and use less energy than use more energy than LCD CRT monitors monitors 63 64 Monitor Specifications Printers A printer is a peripheral device that produces a Screen size – The diagonal measurement of the screen surface physical copy or hard in inches (15, 17, 19, 21) copy of the computer’s Resolution – The sharpness of the image determined by the output number of horizontal and vertical dots (pixels) that the screen can display (800 x 600, 1024 x 768, 1600 x 1200) Refresh rate – The speed at which the screen is redrawn (refreshed) and measured in Hertz (Hz) (60Hz, 75Hz) 65 66 11 K.Ng Sept08
  12. 12. Types of Printers Plotter Inkjet Laser Inkjet printer also called a printer, Laser printer works like a bubble-jet, makes characters copier by inserting dots of ink onto Quality determined by dots A plotter is a printer that uses a pen that moves over a paper per inch (dpi) produced large revolving sheet of paper Letter-quality printouts Color printers available Cost of printer is inexpensive Expensive initial costs but It is used in engineering, drafting, map making, and but ink is costly cheaper to operate per page seismology 67 68 Memory vs. Storage Why Is Storage Necessary? Hard Drive – storage RAM – memory Storage devices: Retain data when the computer is turned off Storage, Storage also known as mass media or auxiliary storage, storage Are cheaper than memory refers to the various media on which a computer system can Play an important role during startup store data Are needed for output Storage devices hold programs and data in units called files Memory is a temporary workplace where the computer transfers the contents of a file while it is being used 69 70 Hard Disks A Bit of HD History Platter Read/Write • Guess how big this HD can store? head Hard disks are high speed, high capacity storage devices high-speed high-capacity They contain metal disks called platters They contain two or more stacked platters with read/write heads for each side IBM System 305: 1st computer with a hard drive in 1956 Hard disks can be divided into partitions to enable computers to work with more than one operating system There were 50 24”∅ platters and could store 5MB!!! 71 72 12 K.Ng Sept08
  13. 13. More Hard Drives (I) More Hard Disks (II) Removable Hard Disks (getting outdated) Getting smaller (physical size) : Platter is enclosed in a cartridge e.g. Toshiba 0.85” 2-4GB HD in 2004. Can be inserted into a drive bay Secondary storage – storage that isn’t directly available And bigger (storage size) : gg ( g ) e.g. Hitachi 3.5” 1TB HD in 2Q 2007. Internet Hard Drives Storage space on a server Or Both : Subscription service e.g. Fujitsu 2.5” 300GB 4200rpm HD (MHX2300BT) in Feb. 2007 e.g. Toshiba 1.8” 100GB 4200rpm HD in Jan. 2007 73 74 More Hard Disks (III) Factors Affecting a Hard Disk’s Performance Spins faster : e.g. Seagate’s 2.5” Savvio 15K Series HD 36GB/73GB at 15,000rpm. Seek time or positioning performance – How quickly the read/write head positions itself and begins transferring information. It is measured in Flash-memory based HD (Solid State Disks SSD) milliseconds (ms) e.g. SanDisk’s 32GB 1.8” SSD in Jan. 2007 at about US$600.00 Spindle speed or transfer performance – How quickly the drive transfers data. It is measured in rotations per minute (RPM) 75 76 Floppy and Zip Disks and Drives Protecting the Data on Your Disks Floppy Drive Zip Drive Don’t touch the surface of the disk Don’t expose disk to magnetic fields Avoid contamination (food, drink) Floppy Disk Avoid condensation A di k or diskette is a portable storage medium disk di k i bl di High-density floppy disks that are commonly Avoid excessive temperatures used today store 1.44 MB of data Disks work with a disk drive Zip disks store up to 750 MB of data and are not downwardly compatible with floppy disks 77 78 13 K.Ng Sept08
  14. 14. CD-ROM Discs and Drives CD-R and CD-RW Discs and Recorders CD-ROM stands for Compact Disc- CD-R CD-RW Read Only Memory Discs can be read and Discs can be read and CD-ROM drives can not write data written to written to to discs Discs can only be Discs are erasable They are capable of storing 650 MB written to “once” Discs can be written to of data CD-R drives are capable many times They are used for storing operating of reading and writing CD-RW drives are systems, large application programs, data capable of reading, and multimedia programs writing, and erasing data 79 80 DVD-ROM Discs and Drives DVD-RW and DVD+RW Discs DVD stands for Digital Video DVD-R and DVD+R drives have the ability to Disc read/write data DVD technology is similar to DVD-RW and DVD+RW drives allow you to write, CD-ROM technology erase, and read from a disc many times DVDs are capable of storing up to 17GB of data The data transfer rate of DVD drives is comparable to that of hard disk drives 81 82 Protecting Data on Discs The Future of Optical Storage (1) Do not expose discs to excessive heat Blu-Ray Disc (BD) Do not touch underside of discs 140 members: Sony, Samsung, LG, Walt Disney Pictures, Twentieth Century Fox …etc. Do not write on the label side of discs with a 25GB/50GB hard instrument Single layer can hold >2 hrs. of HDTV 2 Do not stack discs blue-violet laser (405nm) Store discs in original boxes 83 84 14 K.Ng Sept08
  15. 15. The Future of Optical Storage (II) Solid State Storage Devices HD DVD Solid state storage devices use nonvolatile memory Developed by Toshiba and NEC chips to retain data 15GB/30GB They do not have moving p y g parts They are small, lightweight, reliable, and portable 85 86 Solid State Storage Devices Summary Memory • Input is the software, data, and information that is Smart Stick entered into the computer’s memory Card • Input devices such as the keyboard, mouse, and trackball enable the user to enter data Secure Digital Compact • A pointing device enables the user to control (SD) M Memory Flash (CF) Memory movements of an on-screen pointer f i • Speech recognition software enables the user to enter data into a computer by speaking into a microphone • Monitors enable the user to view the computer’s USB Thumb processed data; the output is known as soft copy Drives 87 88 Summary (continued) Summary (continued) • The two types of monitors are the CRT and the LCD • A hard disk’s performance is measured by its positioning • A monitor’s quality is measured by screen size, resolution, and performance and transfer rate refresh rate • Optical storage devices include: • Printers produce permanent versions (hard copies) of the CD-ROM– Read-only computer’s output CD-R– Record once • The two basic types of printers are the inkjet and laser CD-RW– Erasable, write repeatedly • M Memory makes software and d t available for the CPU’s use k ft d data il bl f th CPU’ DVD-ROM/DVD+ROM – Read-only • Storage devices are categorized by: DVD-R/DVD+R– Read/write Read-only DVD-RW/DVD+RW – rewritten many times Read/write • Solid state storage devices include: Random access PC cards Near online (secondary) Flash memory cards Smart cards 89 90 15 K.Ng Sept08