Computer Concepts 7

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Computer Concepts
7 t h E d i t i o n
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Chapter 2 Computer Hardware
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Chapter 2Computer Hardware

• Section A Data Representation and Digital
  Electronics

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Chapter Preview

• After this chapter, you should be able to
• Explain why most computers are digital
• Describe the role of the ALU
• List factors that affect performance
• Explain RAM
• Compare storage technologies
• Describe computers expansion bus
• Explain hardware compatibility considerations

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Data Representation How do computers represent
data digitally?

• Data representation makes it possible to convert
  letters, sounds, and images into electrical
  signals
• Digital electronics makes it possible for
  computer to manipulate simple on and off
  signals to perform complex tasks
• A digital device works with discrete data or
  digits, such as 1 and 0
• An analog device works with continuous data such
  as sound waves

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Data Representation How do computers represent
data digitally?

• Computers are digital primarily because digital
  technology is simple, dependable, and adaptable
• Just as a standard light switch is a simpler
  technology than a dimmer, so is digital when
  compared to analog

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How can a computer represent numbers?

• Unlike the decimal system, the binary number
  system (base 2) uses only two digits 0, and 1
• The following table lists some decimal numbers
  and their binary equivalent

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How can a computer represent words and letters
using bits?

• Character data is composed of letters, symbols,
  and numerals that will not be used in arithmetic
  operations
• ASCII (American Standard Code for Information
  Interchange) requires only 7 bits for each
  character
• Extended ASCII uses eight bits for each character

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How can a computer represent words and letters
using bits?

• EBCDIC (Extended Binary-Coded Decimal Interchange
  Code) is an alternative 8-bit used by older IBM
  systems
• Unicode uses 16 bits and provides codes for
  65,000 characters a bonus for representing
  alphabets of multiple languages
• Used for foreign language support

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How does a computer convert sounds and pictures
into codes?

• Sounds and pictures must be transformed into a
  format the computer can understand
• A computer must digitize colors, notes, and
  instrument sounds into 1s and 0s

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Quantifying Bits and bytes How can I tell the
difference between bits and bytes?

• A bit is one binary digit (b)
• 0
• A byte is 8 bits (B)
• 0010 0100
• A nibble is 4 bits
• 0011

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Quantifying Bits and bytes How can I tell the
difference between bits and bytes?

• Kilo- means a 1000, Mega- means million, Giga
  -means billion
• Kilobit (Kb) is 1,024 bits
• Kilobyte (KB) is 1, 024 bytes
• Megabyte (MB) is 1,048,576 bytes
• Gigabyte (GB) is 1,073,741,824 bytes

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Does a typical computer owner need to mess around
inside the system unit?

• Desktop units are designed with expectation that
  the home user may add or update the equipment
• Notebook computers are not designed for users to
  access all areas. Although users can update
  certain components

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Does a typical computer owner need to mess around
inside the system unit?
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Whats a computer chip?

• Most electronic components inside a computer are
  integrated circuits - thin slices of silicon
  crystal packed with microscopic circuit elements
• Wires
• Transistors
• Capacitors
• Logic gates
• Resistors

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Whats a computer chip?

• Semiconducting materials are used to fabricate a
  chip
• Types of chips
• DIPs
• DIMMs
• PGAs
• SEC cartridge

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Whats a computer chip?
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How do chips fit together to make a computer?

• The motherboard houses all essential chips and
  provides connecting circuitry between them

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How do chips fit together to make a computer?
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Chapter 2Computer Hardware

• Section B Microprocessors and Memory

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Microprocessor BasicsWhat exactly is a
microprocessor?

• A microprocessor is an integrated circuit
  designed to process instructions
• CPU on a chip

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How does a microprocessor work?

• The CPU has two parts
• ALU (arithmetic logic unit)
• Performs arithmetic operations
• Performs logical operations
• Uses registers to hold data being processed
• The CPUs control unit directs and coordinates
  processing

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Can I replace my computers microprocessor with a
faster one?

• Technically yes, but most computer owners rarely
  do
• Reasons not to upgrade
• Cost
• Technical factors speed
• Do research before you upgrade your microprocessor

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Random Access Memory What is RAM?

• RAM (random access memory) - an area of the
  computer that temporarily holds data before and
  after it is processed
• As you type, characters are held in RAM

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How much RAM does my computer need?

• RAM is primary storage (main memory)
• Measured in megabytes (MB) or gigabytes (GB)
• Todays computers have between 128 MB and 2 GB of
  RAM
• Depends on software you use
• You can purchase additional RAM
• A computer can use disk storage to simulate RAM.
  This is called virtual memory
• Not as fast as RAM

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Do all computers use the same type of RAM?

• No. RAM components vary in speed, technology, and
  configuration
• Speed is measured in nanoseconds. 1 nanosecond
  (ns) is 1 billionth of a second
• It can also be expressed in MHz (millions of
  cycles per second)
• SDRAM (Synchronous Dynamic RAM)
• RDRAM (Rambus Dynamic RAM)

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Read-Only Memory How is ROM different from RAM?

• ROM (read-only memory) is one or more chips
  containing instructions that help a computer
  prepare to process tasks
• ROM is permanent and non-volatile
• Only way to change the instructions on a ROM chip
  is to replace the chip

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CMOS memory Where does a computer store its
basic hardware settings?

• A computer needs a semi-permanent way of keeping
  boot data, such as the number of hard disk
  sectors and cylinders
• CMOS memory - holds data but requires very little
  power to retain its contents
• Retains important computer settings after you
  turn the power off
• Can run by a battery on the motherboard
• Housed within the same chip carrier as ROM BIOS

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Where does a computer store its basic hardware
settings?
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Chapter 2Computer Hardware

• Section C Storage Devices

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Storage Basics What are the basic components of
a data storage system?

• A storage medium is the disk, tape, CD, DVD,
  paper or other substance that contains data
• A storage device, such as a floppy disk drive, a
  hard drive, zip drive, CD drive, and a DVD drive,
  is used to store the data

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How does magnetic storage work?

• Magnetic storage - stores data by magnetizing
  microscopic particles on the disk or tape surface
• Read-write head - mechanism in the disk drive
  that reads and writes magnetized particles that
  represent data

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How does magnetic storage work?
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How does optical storage work?

• Optical storage stores data as microscopic light
  spots (lands) and dark spots (pits) on the disk
  surface
• Data recorded on optical media is generally
  considered to be less susceptible to
  environmental damage than data recorded on
  magnetic media

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How does optical storage work?
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Can I add storage devices to my computer?

• Devices can be added into empty drive bays

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Floppy disk Technology Why is it called a
floppy disk?

• A floppy disk is a round piece of flexible mylar
  plastic covered with a thin layer of magnetic
  oxide and sealed inside a protective casing

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How much data can a floppy disk hold?

• 3 ½ diskettes have capacity of 1.44 MB
• Other floppy disk types
• ZIP disks 100 MB, 250 MB, and 750 MB
• Superdisks 120 MB or 240 MB

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How can ZIP disks and Superdisks store more data
than standard floppy disk?

• Disk density - closeness and size of magnetic
  particles it stores
• Zip disks and Superdisks store data at a higher
  density than a standard 3 ½ floppy disk

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What are the advantages and disadvantages of
floppy disk technology?

• Major advantage portability
• Major disadvantage not a particularly speedy
  device and limited storage capacity
• Today most software vendors use CD-ROM or DVD-ROM
  disks instead

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How does a hard disk work?

• Hard disk platter - a flat, rigid disk made of
  aluminum or glass and coated with magnetic oxide
• Density far exceeds floppy disk
• Hard disk - one or more platters and their
  associated read-write heads.
• Preferred type of main storage

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How does a hard disk work?
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Whats the downside of hard disk storage?

• Head crash - when a read-write head runs into a
  dust particle or other contaminant on the disk
• Head crash damages some data on disk
• Triggered by jarring the hard disk while in use
• Not limited to hard disks

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Tape Storage Whats the purpose of a tape drive?

• Tape backup - copy of data on hard disk stored on
  magnetic tape
• Relatively inexpensive
• Not suitable for everyday storage tasks
• Sequential-access storage medium

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CD and DVD technology Is there a difference
between CD and DVD technology?

• CD
• Holds up to 80 minutes of music or 700 MB of data
• DVD
• Holds about 4.7 GB of data
• Upcoming DVD standards will further increase the
  storage capacity

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How do CD and DVD drives work?
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How do CD and DVD drives work?

• Recordable technology uses a laser to change the
  color in a dye layer sandwiched beneath the clear
  plastic disk surface
• Rewritable technology uses phase change
  technology to alter a crystal structure on the
  disk surface

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Can I use a single drive to work with any CD or
DVD media?
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Are rewritable CD or DVD drives an replacement
for a hard disk?

• It is slower than hard disk access therefore not
  a suitable replacement yet

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Is my computer DVD drive the same as the one
connected to my television set?

• Not exactly. Movie files are still very large.
  Television DVD drives include MPEG decoding
  circuitry
• Most movie DVDs are encoded in MPEG-2 data coding
  format

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Solid State Storage When would I use solid state
storage?

• Portable, provides fast access to data and uses
  very little power
• Widely used in digital cameras, MP3 music
  players, notebook computers, PDAs, and cell
  phones
• You can use solid state storage as you would a
  floppy disk
• USB flash drive
• CompactFlash card
• MMC
• SecureDigital
• SmartMedia

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Chapter 2Computer Hardware

• Section D Input and Output Devices

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Basic Input Devices What devices can I use to
get data into a computer?
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What are my options for display devices?

• CRT (cathode ray tube) uses gun-like mechanisms
  to direct beams of electrons toward the screen
  and activate individual dots of color that form
  an image
• LCD (liquid crystal display) produces an image by
  manipulating light within a layer of crystal
  cells
• LCDs are clearer, have low radiation emission,
  are portable, and compact
• LCDs are also more expensive than CRTs

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What are my options for display devices?

• Plasma screen technology creates an on-screen
  image by illuminating miniature colored
  fluorescent lights arrayed in a panel-like screen
• Lightweight, compact, and more expensive than CRT
  monitors

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How does an ink jet printer work?

• Nozzle-like print head that sprays ink onto paper
  to form characters and graphics
• Most ink jet printers use CMYK color

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How do laser printers compare to ink jet printers?

• A laser printer uses the same technology as a
  photocopier to paint dots of light on a
  light-sensitive drum
• Higher quality than ink jet
• More expensive to buy than ink jet
• Less expensive to operate than ink jet

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Is a laser better than an ink jet?
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What is a dot matrix printer?

• Dot matrix printers produce characters and
  graphics by using a grid of fine wires
• Introduced in 1970s
• Low quality output
• Used for back-office applications that demand
  low operating cost and dependability
• Can print multipart carbon forms

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Why would anyone want a dot matrix printer?
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What other printer technologies are available?

• Thermal transfer printer
• Uses page-sized ribbons coated with wax
• Print head consists of heating elements to melt
  the wax
• Dye sublimation printer
• Similar to wax, but page-sized ribbon contains
  dye
• Print heads diffuse the dye

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Printers What features should I look for in a
printer?

• Resolution
• Printer resolution is measured in dpi (dots per
  inch), the number of dots it can print per linear
  inch
• Come in color or black and white

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What features should I look for in a printer?

• Print speed
• Measured either by pages per minute (ppm) or
  characters per second (cps)
• Color takes longer than black and white
• Text prints faster than graphics
• Ten pages per minute (black and white) typical
  speed for todays jet and laser printers

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What features should I look for in a printer?

• Duty cycle - indication of the number of pages a
  printer can be expected to print per month
• Indicates maintenance costs
• Operating costs
• Printers require ongoing costs including ribbons,
  ink cartridges, and toner
• Per copy cost is the cost of printing a page with
  an average amount of text, graphics, and color
• Memory
• A computer sends data for a printout to the
  printer along with a set of instructions on how
  to print the data

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Installing Peripheral Devices Is it difficult to
install a new peripheral device?

• Internal devices
• Tools required
• Screwdriver
• Directions
• Before installing
• Unplug the computer
• Ground yourself
• Installing
• Follow the directions

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What is an expansion slot?

• Expansion slot - long, narrow socket on the
  motherboard into which you can plug an expansion
  card
• Graphics card (for connecting monitor)
• Modem (for transmitting data over phone or cable
  lines)
• Sound card (for connecting speakers)
• Expansion card - small circuit board that
  provides computer with ability to control
  storage, input or output device
• Most computers have 4 - 8 expansion slots

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What is an expansion slot?
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What are the major types of expansion slots?

• ISA (Industry Standard Architecture)
• Used today only for some modems and other
  relatively slow devices
• PCI (Peripheral Component Interconnect)
• Offers fast transfer speeds and a 32-bit or
  64-bit data bus
• AGP (Accelerated Graphics Port)
• Provides a high-speed data pathway primarily used
  for graphics cards

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Do notebook computers also contain expansion
slots?

• Most notebook computers are equipped with a
  special type of external slot called a PCMCIA
  slot (personal computer memory card international
  association)
• Typically a notebook only has one slot, but the
  slot can hold more than one PC card (PCMCIA
  expansion cards)

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What is an expansion port?

• To connect a peripheral device to an expansion
  card, you plug a cable from the device into the
  expansion port
• Expansion port - any connector that passes data
  in and out of a computer or peripheral device

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What is an expansion port?
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How do I know which port to use?
Serial DB-9
ParallelDB-25M
USB
SCSIC-50F
IEEE 13394
VGAHDB-15
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Conclusion

• You should now be able to
• Explain why most computers are digital
• Describe the role of the ALU
• List factors that affect performance
• Explain RAM
• Compare storage technologies
• Describe computers expansion bus
• Explain hardware compatibility considerations

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