James Tam Introduction to hardware Concepts covered Units of measurement Processors Memory Input and output Storage Peripherals

James Tam Basic units of measurement Bit binary digit smallest unit of measurement two possible values Byte 8 bits 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

James Tam Large units of measurement (storage size) Note: use powers of two because computer storage (bytes) are based on the basic unit (bit). ~ 20 million four-drawer filing cabinets full of text Kilobyte (kB) – a thousand bytes (1,024 = 2 10 ) Megabyte (MB) - a million (1,048,576 = 2 20 ) Gigabyte (GB) – a billion (1,073,741,824 = 2 30 ) Terabyte (TB) – a trillion (1,099,511,627,776 = 2 40 ) Petabyte (PB) – a quadrillion ( e+15 = 2 50 )

James Tam Small units of measurement (speed) millisecond (ms) – a thousandth of a second (1/1,000 = ) microsecond (μs) - a millionth of a second (1/1,000,000 = ) nanosecond (ns) – a billionth of a second (1/1,000,000,000 = )

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

James Tam High level view of the hardware in a computer

James Tam Processor

James Tam Processor The brains of a computer (maybe not…) A real processor

James Tam 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!

James Tam 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 ( seconds between each pulse or 40 ns between pulses)

James Tam Some common types of processors Intel processors (usually run some version of MS-Windows) Type of processorClock speed Celeron500 MHz – 1.3 GHz Pentium III650 MHz – 1.2 GHz (1200 MHz) Pentium IV1.4 GHz (1400 MHz) – 2.2 GHz (2200 MHz) PowerPC processors in Apple computers Type of processorClock speed G3500 MHz – 700 MHz G4733 MHz or 867 MHz

James Tam 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.

James Tam Memory

James Tam Types of memory 1) RAM 2) ROM 3) Caches

James Tam 1) RAM (Random access memory) Often used for short term storage of information

James Tam Characteristics of RAM Volatile Used for temporary storage Typical ranges 128 MB ~1 GB

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

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

James Tam 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

James Tam Input

James Tam Input devices Used by a person to communicate to a computer. Person to computer

James Tam Common input devices Keyboard Mouse

James Tam Output

James Tam Output devices Displays information from the computer to the a person. Computer to a person

James Tam Most common output device A computer monitor

James Tam How many monitors work Images are displayed with dots (pixels) Picture from Beekman

James Tam Quality of monitors determined by 1)Size 2)Resolution 3)Color depth 4)Dot pitch

James Tam 1) Monitor quality (size) Measured diagonally

James Tam 2) Monitor quality (resolution) Columns of pixels x Rows of pixels Col 1, Row 1 Col 2, Row 1 Col 3, Row 1 …Col [c], Row 1 Col 1, Row 2 Col [c], Row 2 Col 1, Row 3 Col [c], Row 3 :: Col 1, Row [r] Col 2, Row [r] Col 3, Row [r] …Col[c], Row[r]

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

James Tam 3) Monitor quality (effects of color depth) 16 million colors 256 colors 16 colors 2 colors

James Tam 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 = MB

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

James Tam 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)

James Tam Types of monitors 1)CRT – use three electron guns (shown on previous slides) 2) LCD (flat screen) – use a liquid crystal display

James Tam 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

James Tam Storage

James Tam 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”

James Tam Types of storage 1)Optical CD-ROM DVD 2) Magnetic Hard drives Floppy disks

James Tam 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

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

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

James Tam 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 The re-melted part reflects light again

James Tam 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, rpm)

James Tam 2) Magnetic drives (floppy) Pros Portable Cheap Cons Slow Low storage capacity (1.44 MB)

James Tam 2) Magnetic drives (structure) Platters (hard drives only!) Tracks (inside circles)

James Tam 2) Magnetic drives (structure) Sectors (wedges)

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

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

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

James Tam Ports Are used to connect the computer to outside devices Serial, parallel Ports on older computers (slower, 1 port to one device) USB (Universal serial bus) Standard on newer computers (faster, up to 127 devices on 1 port) Firewire Fast (video)

James Tam Printers Allows text or graphics to be printed out on paper Common types Inkjet Laser

James Tam How inkjet printers work. Use a series of nozzles to spray drops of ink directly on the paper Printer heads Ink nozzles

James Tam Characteristics of Inkjet printers Printer costs less (black and white ~ $70.00, color ~$ ) Cost per page is more Slower Text is lower quality, color pictures may be higher quality

James Tam How laser printers work Use a laser to produce patterns on an ink drum using static electricity

James Tam Characteristics of Laser printers Printers cost more (black and white ~ $ , color ~$ ) Cost per page is less Faster Text is higher quality, color pictures may be lower quality

James Tam Some other peripherals Scanners Cameras Speakers Joysticks

James Tam Summary Important concepts What is hardware and what are common units of measurement used Processors – what do they do, what are their characteristics, types of processors Memory – what is it, types of memory What is the purpose of an input device, types of input devices What is an output device, types of output devices General characteristics of computer monitors Storage devices – different types and how they work Other parts of a computer (beyond the simple model) – motherboard, buses, ports Common peripherals (printers, scanners, cameras)