Introduction to hardware

1
Introduction to hardware

• Concepts covered
• Units of measurement
• Processors
• Memory
• Input and output
• Storage
• Peripherals

2
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 (1.125899906843e15
250)
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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)
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What is hardware?

• Hardware includes the physical components of a
  computer system e.g., a monitor, keyboard, mouse
  and the computer itself.

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High level view of the hardware in a computer
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Processor
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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)

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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

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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.

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Memory
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Types of memory

• 1) RAM
• 2) ROM
• 3) Caches

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1) RAM (Random access memory)

• Often used for short term storage of information

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Characteristics of RAM

• Volatile
• Used for temporary storage
• Typical ranges 128 MB 1 GB

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2) ROM (Read only memory)

• You can read but not change the contents
• Contents written to (burnt) by special equipment
• Non-volatile

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Types of ROM

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

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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

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Input
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Input devices

• Used by a person to communicate to a computer.

Person to computer
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Common input devices

• Keyboard
• Mouse

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Output
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Output devices

• Displays information from the computer to the a
  person.

Computer to a person
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Most common output device

• A computer monitor

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How many monitors work

• Images are displayed with dots (pixels)

Picture from Beekman
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Quality of monitors determined by

• Size
• Resolution
• Color depth
• Dot pitch

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1) Monitor quality (size)
Measured diagonally
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2) Monitor quality (resolution)

• Columns of pixels x Rows of pixels

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

• 16 million colors

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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
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4) Monitor quality (dot pitch)
3 guns form 1 color dot

• Dot pitch is the distance between the center of
  each color dot (mm)

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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)
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Types of monitors

• CRT use three electron guns (shown on previous
  slides)

2) LCD (flat screen) use a liquid crystal
display
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CRTs vs. LCDs

• 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
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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

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Types of storage

• Optical
• CD-ROM
• DVD
• 2) Magnetic
• Hard drives
• Floppy disks

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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/RWs) stores even more info

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1) CDs and DVDs (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

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1) CDs and DVDs (recording information)

• A strong laser (write laser) heats selected parts
  of the disc.

CD
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1) CDs and DVDs (erasing the information)

• A laser (erase laser) heats selected parts of the
  disc (not quite as hot as a write laser).

CD
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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)

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2) Magnetic drives (floppy)

• Pros
• Portable
• Cheap
• Cons
• Slow
• Low storage capacity (1.44 MB)

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2) Magnetic drives (structure)
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2) Magnetic drives (structure)
Sectors (wedges)
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2) Magnetic drives (structure)
A cylinder (a bunch of sectors on different
platters, one on top of the other hard drives
only)
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Motherboard (Systemboard, Mainboard)

• Many parts of the computer are attached to it.

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Buses

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

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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)

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Printers

• Allows text or graphics to be printed out on
  paper
• Common types
• Inkjet
• Laser

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How inkjet printers work.

• Use a series of nozzles to spray drops of ink
  directly on the paper

Printer heads
Ink nozzles
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Characteristics of Inkjet printers

• Printer costs less (black and white 70.00,
  color 100.00)
• Cost per page is more
• Slower
• Text is lower quality, color pictures may be
  higher quality

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How laser printers work

• Use a laser to produce patterns on an ink drum
  using static electricity

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Characteristics of Laser printers

• Printers cost more (black and white 300.00,
  color 3000.00)
• Cost per page is less
• Faster
• Text is higher quality, color pictures may be
  lower quality

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Some other peripherals
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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)