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Module 2

Module 2. How Computers Work. Basic Functions of an Operating Systems. Input – recognizing input from the keyboard or mouse Processing –- manipulating data according to the user's instructions Output – sending output to the video screen or printer

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Module 2

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  1. Module 2 How Computers Work

  2. Basic Functions of an Operating Systems • Input – recognizing input from the keyboard or mouse • Processing –- manipulating data according to the user's instructions • Output – sending output to the video screen or printer • Storage – keeping track of files for use later; examples of storage devices include floppy disks and hard drives.

  3. Bootstrap • For an operating system to run, it must be loaded into the computer's Random Access Memory (RAM). • When a computer is first turned on, it launches a small program called the bootstrap loader that is located on the BIOS chip on the motherboard. • The bootstrap's primary functions are to test the computer's hardware and to locate and load the operating system into RAM.

  4. Power-On Self Test • To test the computer's hardware, the bootstrap program runs a program called power-on self-test or POST. • In this test, the computer's Central Processing Unit (CPU) checks itself first and then checks the computer's system timer. • The POST checks the Random Access Memory (RAM) by writing data to each RAM chip and then reading that data. Any difference indicates a problem. • If the POST finds errors, it sends a message to the computer monitor. If the POST finds errors that cannot be displayed on the monitor, it sends errors in the form of "beeps." • The POST sends one beep and the screen begins to display OS loading messages once the bootstrap has determined that the computer has passed the POST.

  5. Generic Cold Boot Sequence

  6. Desktop / Tower Models

  7. Tower Models • Power • Floppy disk drive CD-ROM drive • Hard disk drive • LEDs • NIC • Video card • Audio card • Parallel port • Serial port • Mouse Port

  8. Power Supplies • Converts AC to DC • Typically 250 –300 watts • AT • P8 & P9 connector • 12 pin • +5, -5, +12, -12 • ATX • P1 connector • 20 pin (keyed) • +3.3,+5, -5, +12, -12

  9. Cooling Systems • The power supply fan helps prevent the computer components from overheating by maintaining airflow in the case. • Overheating is a critical problem that can cause a computer system to malfunction or fail. • A heat sink is made of a material that absorbs the heat generated.

  10. Motherboards • System board / main board is crucial because it is the nerve center of the computer system. Everything else in the system plugs into it, is controlled by it, and depends on it to communicate with other devices on the system. • It generally houses the CPU, the controller circuitry, the bus, RAM, expansion slots for additional boards, and ports for external devices. In addition, it contains the CMOS and other ROM BIOS and support chips providing varied functionality.

  11. Motherboard Form Factors • Describe their physical dimensions. • AT • ATX • The ATX motherboard is similar to the Baby AT motherboard, except for a number of important enhancements. Most new systems come with the ATX motherboard form factor.

  12. Motherboard Components • The major components on the motherboard include: • chipset – interconnects all the devices on the motherboard • CPU socket • expansion sockets • I/O support • BIOS • RAM sockets • power supply socket • CMOS chip • dip switches and jumpers • memory cache

  13. The Motherboard

  14. The Motherboard

  15. The Motherboard

  16. The Motherboard

  17. Inside the Computer Power Supply Hard (C) Drive Floppy (A) Drive CD (D) Drive

  18. Back Plane Card Speaker Sound Card RAM Video Card Motherboard Processor

  19. printer connector USB ports Mouse and keyboard connector joystick connector ISA slot AMR slot processor (ZIF) socket AGP slot chipset power connector DIMM memory slots CD Drive hard drive IDE connectors Floppy connector PCI slots

  20. ISA slot Expansion Slots AMR slot AGP slot PCI slots ISA – Industry Standard Architecture AMR – Audio/Modem Riser AGP – Accelerated Graphics Port PCI – Peripheral Component Interconnect

  21. Dual Processor Motherboard power connector DIMM memory slot IDE connectors CD Drive hard drive Floppy connector SIMM memory slots processor (ZIF) socket keyboard connector PCI slot PC bus slots system board IC ISA slots parallel port PRT 1 VESA slot COM 1 COM 2

  22. system RAM Floppy connector IDE connectors CD Drive hard drive System board IC power connector Expansion slots PS/2 or Mini-Din ISA slot mouse keyboard speaker AMR slot AGP slot PCI slots mic USB Com 2 game port line-in parallel port/PRT 1 Com 1

  23. USB RJ-45 DB-15 – Serial Port 1/8” Stereo Phone Jacks DB-9 – Com 1 and Com 2 PS/2 - Mini Din – Keyboard and Mouse DB-15 – Video Port

  24. Central Processing Units

  25. Central Processing Unit • Most important elements of the personal computer. • On the motherboard, the CPU is contained ona single integrated circuit called the microprocessor. • The computer will not run without a CPU. • Often referred to as the brains of a computer, the CPU contains two basic components: • Control unit • Arithmetic/Logic Unit (ALU)

  26. Control Unit • Instructs the rest of the computer system on how to follow a program's instructions. • It directs the movement of data to and from processor memory. • The control unit temporarily holds data, instructions, and processed information in its arithmetic/logic unit. • In addition, it directs control signals between the CPU and external devices such as hard disks, main memory, I/O ports, etc.

  27. Processor Speed • CPU descriptions as Pentium 133, Pentium 166, or Pentium 200 are well known. These numbers are specifications that indicate the maximum (reliable) operating speed at which the CPU can execute instructions. • The CPU speed is not controlled by the microprocessor itself, but by an external clock located on the motherboard. • The speed of the processor is determined by the frequency of the clock signal. Typically expressed in megahertz (MHz), and the higher the number, the faster the processor.

  28. BIOS ROM • The basic input/output system (BIOS) contains the instructions and data in the ROM chip that control the boot process and the computer hardware. • BIOS is sometimes called firmware. • The ROM chip that contains the firmware is called the ROM BIOS chip, ROM BIOS, or simply BIOS.

  29. Expansion Cards Video card Modem card Sound card Network card AGP

  30. Expansion Slots • Sockets, are receptacles on the computer motherboard that accept printed circuit boards. They allow additional devices to be added. • Examples include video cards, I/O cards, andsound cards. • Common expansion slots: • Industry Standard Architecture (ISA ) – 8 MHz, 16-bit • Peripheral Component Interconnect (PCI ) – 33 MHz, 32 and 64-bit • Accelerated Graphics Port (AGP) - video adapters – 32-bit

  31. Riser Cards AMR Riser card CNR

  32. Riser Cards

  33. System Buses

  34. RAM – Random Access Memory (SIMMS / DIMMS / RIMMS)

  35. RAM – Random Access Memory (SIMMS / DIMMS Installation)

  36. Cache Memory • L1 cache is located on the CPU. • L2 cache is located between the CPU and DRAM. • L1 cache is faster than L2 because it is located within the CPU and runs at same speed as the CPU. • It is the first place the CPU looks for its data. • If data is not found in L1 cache, the search will then continue with L2 cache, and then on to main memory. • COASt modules are used to provide cache memory on many Pentium-based systems.

  37. Monitors • Computers are usually connected to a display, also called a monitor. • Some key monitor-related terms are: pixels, refresh rate, resolution, and size. Measure screen size diagonally. • Pixels – Are picture elements. The screen image is made of pixels (tiny dots), which are arranged in rows across the screen. Each pixel consists of three colors: red, green, and blue (RGB). • Dot pitch – A measurement of how close together the phosphor dots are on the screen. The finer the dot pitch, the better image quality (measured in millimeters).

  38. Display Technology • CRT – Cathode Ray tube • LDC – Liquid Crystal Display • Cable technology - VGA and DVI are the two most common. • Viewable area (usually measured diagonally) • Aspect ratio and orientation (landscape or portrait) • Maximum resolution • Dot pitch - Refresh rate - Color depth • Amount of power consumption

  39. Dot Pitch

  40. Refresh Rate, Measured in Hertz (Hz)

  41. Changing Your Screen Resolution

  42. CRT A cathode-ray tube is a special-purpose electron tube in which electrons are accelerated by high-voltage anodes, formed into a beam by focusing electrodes, and projected toward a phosphorescent screen that forms one face of the tube. The beam of electrons leaves a bright spot wherever it strikes the phosphor screen.

  43. Video Card video BIOS video RAM video controller IC

  44. Ports COM Ports USB DB9 DB25--parallel SCSI Firewire Mini-DIN Game Port-DB15 PORTS

  45. I /O Ports • All peripheral devices that connect to the computer such as printers, scanners, and so on, use connectors on the back of the computer known as ports. • Ports: • Serial ports – 1 bit at a time (9 pin male) • Parallel ports – 1 byte at a time • USB (Universal serial bus) – 127 devices daisy chained, hot swappable, 450 Mbps • Modem - RJ11 connectors • NIC – RJ45 connectors • Firewire– 63 devices using cable lengths up to 4.5 m, 400Mbps

  46. Serial Ports • A serial port can be used to connect devices that use a serial interface such as a modem, scanner, mouse, etc. • Generally, a PC can identify up to four serial ports, but the typical computer contains only two, referred to as COM1 and COM2. • A serial port transmits data bits one after the other (serially) over a single line.

  47. Parallel Ports • A parallel port is a socket on the computer that is used to connect a printer or other peripheral device such as a portable hard disk, tape backup, scanner, or a CD-ROM. • The parallel port contains eight lines for transmitting an entire byte (8 bits) across the eight data lines simultaneously. • Parallel ports can be configured as • LPT1 (IRQ 7) • LPT2 (IRQ 5)

  48. PS/2 Ports • PS/2 keyboard or PS/2 mouse ports (Mini-DIN) are used to connect your PC to its keyboard and mouse. • Both ports look identical, ports are not interchangeable. • Mouse (green) • Keyboard (purple). • Usually both ports are color coded or labeled to avoid any confusion.

  49. USB – Universal Serial Bus • 127 devices • Transfer rate up to 12 Mbps • USB 2.0 up to 450 Mbps • USB keyboards • Mice • Printers • Modems • Scanners • Digital cameras • Digital video cameras • External disk drives

  50. EIDE and SCSI Controllers • The internal hard drive is connected to a disk controller with a cable—a 40 pin cable. • The hard drive and other devices can use one of two types of interface controllers to work with the computer. • These include the Enhanced Integrated Drive Electronics (EIDE), and Small Computer System Interface (SCSI, pronounced "scuzzy") connections.

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