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Introduction to hardware

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  1. Concepts covered • Units of measurement • Processors • Memory • Input and output • Storage • Peripherals Introduction to hardware

  2. Byte • 8 bits Basic units of measurement • Bit • binary digit • smallest unit of measurement • two possible values • Word • The number of adjacent bits that can be stored and manipulated as a unit • 32, 64 for home computers, 128 for the most powerful

  3. Large units of measurement (storage size) • Note: use powers of two because computer storage (bytes) are based on the basic unit (bit). Kilobyte (kB) – a thousand bytes (1,024 = 210) Megabyte (MB) - a million (1,048,576 = 220) Gigabyte (GB) – a billion (1,073,741,824 = 230) Terabyte (TB) – a trillion (1,099,511,627,776 = 240) ~ 20 million four-drawer filing cabinets full of text Petabyte (PB) – a quadrillion (1.125899906843e+15 = 250)

  4. Small units of measurement (speed) • millisecond (ms) – a thousandth of a second (1/1,000 = 10-3) microsecond (μs) - a millionth of a second (1/1,000,000 = 10-6) nanosecond (ns) – a billionth of a second (1/1,000,000,000 = 10-9)

  5. What is hardware? • Hardware includes the physical components of a computer system e.g., a monitor, keyboard, mouse and the computer itself.

  6. High level view of the hardware in a computer

  7. Processor

  8. A real processor Processor (maybe not…) • The brains of a computer

  9. Processor speed • Determined by many things • Type of processor • Clock speed (as measured in Hertz e.g., MHz, GHz) • * But also consider the rest of the computer!

  10. Relationship between clock speed and times between pulses • Examples • 1 Hz = 1 pulse is sent out each second (1 second passes between each pulse) • 10 Hz = 10 pulses are sent out each second (0.1 seconds passes between each pulse) • : • 25 MHz machine = 25 million pulses sent out each second (0.000 000 04 seconds between each pulse or 40 ns between pulses)

  11. Some common types of processors • Intel processors (usually run some version of MS-Windows) • Type of processor Clock speed • Celeron 500 MHz – 1.3 GHz • Pentium III 650 MHz – 1.2 GHz (1200 MHz) • Pentium IV 1.4 GHz (1400 MHz) – 2.2 GHz (2200 MHz) • PowerPC processors in Apple computers • Type of processor Clock speed • G3 500 MHz – 700 MHz • G4 733 MHz or 867 MHz

  12. CISC processors and RISC processors • CISC (Complex Instruction Set Computers • e.g., Pentium; 68000, 68020…(old Apple computers) • RISC (Reduced Instruction Set Computers) • e.g., PowerPC (new Apple computers) • Difference • Instructions on RISC computers are simpler? • Architecture differs between the processors.

  13. Memory

  14. Types of memory • 1) RAM • 2) ROM • 3) Caches

  15. 1) RAM (Random access memory) • Often used for short term storage of information

  16. Characteristics of RAM • Volatile • Used for temporary storage • Typical ranges 128 MB ~1 GB

  17. 2) ROM (Read only memory) • You can read but not change the contents • Contents written to (burnt) by special equipment • Non-volatile

  18. Types of ROM • ROM • PROM • EPROM • EEPROM • Flash Memory (e.g., a computer BIOS, memory for game consoles)

  19. 3) Cache memory • Stores less than RAM but much faster • Can be either part of the processor (L1) or separate from it (L2) • Both are much faster than regular memory RAM

  20. Input

  21. Input devices • Used by a person to communicate to a computer. Person to computer

  22. Common input devices • Keyboard • Mouse

  23. Output

  24. Output devices • Displays information from the computer to the a person. Computer to a person

  25. Most common output device • A computer monitor

  26. How many monitors work • Images are displayed with dots (pixels) Picture from Beekman

  27. Quality of monitors determined by • Size • Resolution • Color depth • Dot pitch

  28. 1) Monitor quality (size) Measured diagonally

  29. 2) Monitor quality (resolution) • Columns of pixels x Rows of pixels

  30. 3) Monitor quality (Color depth) • The number of possible colors that can be displayed for each pixel. 0 1 e.g. monochrome (single color) 2 possible values Uses up 1 bit of space

  31. 3) Monitor quality (effects of color depth) • 16 million colors 16 colors 2 colors 256 colors

  32. Tradeoff between resolution and color depth • There is a limit for both e.g. 16 bit color at 1600 x 1280 = 2 bytes per pixel * 1600 columns of pixel * 1280 rows of pixels = 4.096 MB

  33. dot pitch 4) Monitor quality (dot pitch) • Dot pitch is the distance between the center of each color dot (mm) 3 guns form 1 color dot

  34. Refresh rate of monitors • How fast the screen is redrawn Again there is a tradeoff between resolution and refresh (70 Hz / 70 times per second is usually a good minimum)

  35. Types of monitors • CRT – use three electron guns (shown on previous slides) 2) LCD (flat screen) – use a liquid crystal display

  36. CRT’s vs. LCD’s • CRT • Cost less for the same quality • Sharper images possible (more colors, higher resolution) • Can view images from any angle • LCD • Less eye strain (no flicker and less glare) • Uses less space • Use less power • Weigh less • Lower radiation

  37. Storage

  38. What is the difference between storage and memory? • Memory • keep the information for a shorter period of time • faster • more expensive • “scrap paper for the computer” • Storage • the information is retained longer • slower • cheaper • “file cabinet for the computer”

  39. Types of storage • Optical • CD-ROM • DVD • 2) Magnetic • Hard drives • Floppy disks

  40. 1) Optical CD & DVD • CD ROM (read only) • CD-R: needs a CD-burner to create (record) to a CD • Cheap and portable storage of a lot of data (650 MB) • CD-RW: can write and erase CD to reuse it (rewritable) • DVD-ROM (DVD-ROM/RW’s) – stores even more info

  41. 1) CD’s and DVD’s (recording information) • Use special compounds By default the surface of the CD is reflective A weak laser (read laser) is shot at the disc to determine the reflective portions CD

  42. The melted part no longer reflects light 1) CD’s and DVD’s (recording information) • A strong laser (write laser) heats selected parts of the disc. CD

  43. The re-melted part reflects light again 1) CD’s and DVD’s (erasing the information) • A laser (erase laser) heats selected parts of the disc (not quite as hot as a write laser). CD

  44. 2) Magnetic drives (hard drives) • Stores a lot of information (~20 GB – 80 GB) • Slower than memory (but faster than other forms of storage) • Spin rate (5400, 7200, 10000 rpm)

  45. 2) Magnetic drives (floppy) • Pros • Portable • Cheap • Cons • Slow • Low storage capacity (1.44 MB)

  46. Platters (hard drives only!) Tracks (inside circles) 2) Magnetic drives (structure)

  47. 2) Magnetic drives (structure) Sectors (wedges)

  48. 2) Magnetic drives (structure) A cylinder (a bunch of sectors on different platters, one on top of the other – hard drives only)

  49. Motherboard (Systemboard, Mainboard) • Many parts of the computer are attached to it.

  50. Buses • Connects together the different parts of the computer. • Used for the transfer of information. • Width determines its speed