INFS205

1

• INFS205
• Spring 2004

Computer Concepts 6th EditionParsons/Oja Course
Technologies
2
Computer Hardware
Data Representation and Digital Electronics
Section A
CHAPTER 2
PARSONS/OJA
Page 58
3
Computer Hardware
Chapter 2
Chapter PREVIEW

• When you complete 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
• Compare and contrast technologies for peripherals

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Data Representation and Digital Electronics
Section A
Chapter 2
Digital Data Representation Why are computers
digital?

• Data representation
• Digital electronics
• digital device
• analog device

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Data Representation and Digital Electronics
Section A
Chapter 2
How can a computer represent numbers using bits?

• A computer uses a bit (binary digit) as the
  building block for more complex data
  representations
• Unlike the decimal system, the binary number
  system (base 2) uses only two digits 0, and 1.

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Data Representation and Digital Electronics
Section A
Chapter 2
How can a computer represent words and letters
using bits?

• Character data
• not be used in arithmetic operations
• ASCII
• (American Standard Code for Information
  Interchange)
• EBCDIC
• (Extended Binary-Coded Decimal Interchange Code)
  is an alternative 8-bit used by older IBM systems
• Unicode
• uses 16 bits and provide codes for 65,000
  characters

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Data Representation and Digital Electronics
Section A
Chapter 2
How can a computer represent words and letters
using bits?
extended ASCII table
Page 60
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Data Representation and Digital Electronics
Section A
Chapter 2
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
• Kilo- means a 1000, Mega- means million, Giga
  -means billion, Tera- means trillion, and Exa-
  means quintillion
• Kilobit (Kb)
• Kilobyte (KB)
• Megabyte (MB)
• How many characters (average) can be stored in 1
  MB

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Data Representation and Digital Electronics
Section A
Chapter 2
Does a typical computer owner need to mess
around inside the system unit?
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Data Representation and Digital Electronics
Section A
Chapter 2
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
• resistors

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Data Representation and Digital Electronics
Section A
Chapter 2
Whats a computer chip?
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Data Representation and Digital Electronics
Section A
Chapter 2
The motherboard houses all essential chips and
provides connecting circuitry between them
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Computer Hardware
Microprocessors and Memory
Section B
CHAPTER 2
PARSONS/OJA
Page 66
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Microprocessors and Memory
Section B
Chapter 2
Microprocessor Basics Exactly what is a
microprocessor?

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

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Microprocessors and Memory
Section B
Chapter 2
What does it look like?

• The CPU has two parts
• ALU (arithmetic logic unit)
• performs arithmetic operations
• performs logical operations
• uses registers to hold data being processed
• control unit directs and coordinates processing.
• The list of instructions that a microprocessor
  can perform is called its instruction set

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Microprocessors and Memory
Section B
Chapter 2
Microprocessor Performance Factors What makes
one microprocessor perform better than another?

• CPU speed is influenced by several factors
• clock speed Megahertz, Gigahertz
• word size
• Cache Level 1, Level 2 caches
• instruction set size
• Testing laboratories run a series of tests
  (benchmarks) to gauge the overall speed of a
  microprocessor

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Microprocessors and Memory
Section B
Chapter 2
Whats the difference between CISC and RISC?

• Computers based on a CPU with a complex
  instruction set known as CISC (complex
  instruction set computer) microprocessor
• Intel
• A RISC (reduced instruction set computer) has
  limited set of instructions that it can perform
  quickly
• AMD

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Microprocessors and Memory
Section B
Chapter 2
Can a microprocessor execute more than one
instruction at a time?

• Computers with a single processor execute
  instructions serially (one at a time)
• Pipelining - technology in which the processor
  can begin executing next the instruction before
  it completes the previous instruction
• A computer with more than one processor can
  execute multiple instructions simultaneously,
  referred to as parallel processing
• Supercomputers

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Microprocessors and Memory
Section B
Chapter 2
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

• RAM is a reusable computing source
• RAM is volatile requires power to hold data

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Microprocessors and Memory
Section B
Chapter 2
Why is RAM so important?

• It holds the data and the instructions for
  processing the data
• It even houses OS instructions

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Microprocessors and Memory
Section B
Chapter 2
How much RAM does my computer need?

• RAM is primary storage (main memory)
• Measured in megabytes (MB)
• Use drives amount of RAM
• A computer can use disk storage to simulate RAM.
  This is called virtual memory
• Speed is measured in nanoseconds. 1 nanosecond is
  1 billionth of a second
• It can also be expressed in MHz (millions of
  cycles per second)
• Most computers use SDRAM (synchronous dynamic RAM)

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Microprocessors and Memory
Section B
Chapter 2
Do all computers use the same type of RAM?

• RAM is usually configured as a series of DIPs
  soldered onto a small circuit board called a DIMM
  (dual in-line memory module), RIMM (Rambus
  in-line memory module), or SO-RIMM (small outline
  RIMM)
• DIMMs contain SDRAM, RIMMs and SO-RIMMs contain
  RDRAM

SDRAM chip
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Microprocessors and Memory
Section B
Chapter 2
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
• Since RAM is empty when a computer is turned on,
  ROM BIOS is used
• ROM BIOS (basic input/output system) is a set of
  instructions that tells computer how to access
  the disk drives and peripheral devices

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Microprocessors and Memory
Section B
Chapter 2
Where does a computer store its basic hardware
settings?
Page 73
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Computer Hardware
Storage Devices
Section C
CHAPTER 2
PARSONS/OJA
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Storage Devices
Section C
Chapter 2
Storage Basics What are the basic components
of a data storage system?

• A storage device, such as a floppy disk drive, a
  hard drive, zip drive, and a CD-ROM drive, is
  used to store the data
• A storage medium is the disk, tape, CD, DVD,
  paper or other substance that contains data
• Storing - writing data or saving a file
• Retrieving reading, loading or opening

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Storage Devices
Section C
Chapter 2
Whats the difference between magnetic and
optical storage technologies?

• 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
• Optical storage stores data as microscopic light
  spots (lands) and dark spots (pits) on the disk
  surface
• Data stored on an optical storage device is less
  susceptible to environmental damage

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Storage Devices
Section C
Chapter 2
Whats the difference between magnetic and
optical storage technologies?
Page 77
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Storage Devices
Section C
Chapter 2
Whats the difference between magnetic and
optical storage technologies?
CD-ROM PITS
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Storage Devices
Section C
Chapter 2
Can I add storage devices to my computer?

• Devices can be added into empty drive bays

Click to start
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Storage Devices
Section C
Chapter 2
Which storage technology is best?

• Speed - measured by access time and data transfer
  rate
• Access time - average time it takes a computer to
  locate data and read it
• millisecond one-thousandth of a second
• Random access - ability of a device to jump
  directly to the track or sector holding the data
• floppy disk, hard drive, CD, DVD, zip disks
• Storage capacity - maximum amount of data that
  can be stored on a storage medium

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Storage Devices
Section C
Chapter 2
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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Storage Devices
Section C
Chapter 2
Whats the capacity of a floppy disk?

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

Superdisk
ZIP disk
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Storage Devices
Section C
Chapter 2
How can ZIP disks and Superdisks store so much
more data than standard floppy on the same size
disk?

• Disk density - closeness and size of magnetic
  particles it stores
• High-density disk - stores more data than
  double-density
• Double-sided disk - stores twice as much as
  single-sided
• Zip disks and Superdisks store data at a higher
  density than a standard 3 ½ floppy disk

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Storage Devices
Section C
Chapter 2
Can I protect the data on a floppy disk?

• The write-protect window allows you to protect
  data by making it read-only when it is open, but
  to modify the storage data, it must be closed

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Storage Devices
Section C
Chapter 2
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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Storage Devices
Section C
Chapter 2
How does a hard disk work?
Click to start
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Storage Devices
Section C
Chapter 2
Whats all this business about Ultra ATA, EIDE,
SCSI, and DMA?

• A hard drive mechanism includes a circuit board
  called a controller that positions the disk and
  read-write heads to locate data
• Popular drives
• Ultra ATA (AT attachment)
• EIDE (enhanced integrated drive electronics)
• SCSI (small computer system interface)
• 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

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Storage Devices
Section C
Chapter 2
Can I use a second hard disk drive as a backup?

• Removable hard disk - hard disks that can be
  inserted and removed from drive
• increase storage capacity
• provides security for data
• RAID - (redundant array of independent disks)
• type of hard disk storage
• found on mainframe and microcomputer
  installations
• contains many disk platters
• provides redundancy
• faster data access

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Storage Devices
Section C
Chapter 2
Tape Storage Whats the purpose of a tape
drive?

• Tape
• most popular form of storage in 1960s
• Requires sequential access
• Inconvenient and slow
• Data is arranged as essentially a long sequence
  of bits that begin at one end of the tape and
  stretches to the other
• Tape backup - copy of data on hard disk stored on
  magnetic tape.

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Storage Devices
Section C
Chapter 2
Is it easy to install a tape drive?

• Yes. Tape drives are available in either internal
  or external models

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Storage Devices
Section C
Chapter 2
CD technology Why would I want a CD-ROM drive
in addition to a hard disk drive?

• CD-ROM
• stands for Compact Disc Read-Only Memory
• data stamped on when manufactured
• coated with clear plastic, durable
• estimated life exceeds 500 years
• inexpensive to manufacture
• ideal for distribution of large files

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Storage Devices
Section C
Chapter 2
Whats the capacity and speed of a CD?

• A single CD-ROM holds up to 650 MB
• Original CD-ROM had speeds of 150 KB per second
• Today, speeds of 24x or higher (24 x 150 KB
  per/sec) )

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Storage Devices
Section C
Chapter 2
Whats the difference between CD-ROM and ROM
BIOS?

• They are different technologies
• ROM-BIOS (chip on the motherboard) is magnetic
• CD-ROM (optical storage device) is optical

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Storage Devices
Section C
Chapter 2
Whats the difference between CD-ROM and ROM
BIOS?
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Storage Devices
Section C
Chapter 2
Can I create my own CDs?

• CD DVD
• R stands for compact disc-recordable
• RW Rewritable allows you to create your own CDs
• DVD ROM
• Rewritable requires Phase change technology -
  alters the crystal structure on the disk surface

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Storage Devices
Section C
Chapter 2
Are CDs and DVDs interchangeable?

• CD-ROM drives can not play DVDs
• DVDs can play CD-ROM, most CD-R and most CD-RW
  disks
• Both DVDRW and DVD-RAM can be read on DVD-ROM
  drives

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Computer Hardware
Input and Output Devices
Section D
CHAPTER 2
PARSONS/OJA
Page 88
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Input and Output Devices
Section D
Chapter 2
Expansion slots, cards and ports How does a
computer get data from RAM to a peripheral device?

• Data Bus carries data from one component to
  another
• I/O (computer jargon for input/output) refers to
  collecting data and transporting results.
• Expansion bus - the segment of the data bus that
  transports data between RAM and peripheral devices

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Input and Output Devices
Section D
Chapter 2
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 microcomputers have 4 - 8 expansion slots

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Input and Output Devices
Section D
Chapter 2
What is an expansion slot?
Click to start
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Input and Output Devices
Section D
Chapter 2
What are the major types of expansion slots?

• The microcomputer motherboard typically has up to
  three types of expansion slots
• ISA - older technology, modems and slow devices
• PCI - for graphics, sound, video, modem or
  network cards
• AGP - for graphics cards
• Expansion cards are built for only one type of
  slot

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Input and Output Devices
Section D
Chapter 2
What are the major types of expansion slots?
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Input and Output Devices
Section D
Chapter 2
Do notebook computers also contain expansion
slots?

• 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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Input and Output Devices
Section D
Chapter 2
What is an expansion port?
Expansion port - any connector that passes data
in and out of a computer or peripheral device
Page 90
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Input and Output Devices
Section D
Chapter 2
What are the major types of expansion cables?
Page 90-91
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Input and Output Devices
Section D
Chapter 2
Why do some peripheral devices include a disk
or CD?

• Adding and device
• Software device driver manually add
• Plug and Play (PnP) automatically takes care of
  these technical details
• A Graphics card takes signals from the processor
  and uses them to paint images on the screen

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Input and Output Devices
Section D
Chapter 2
Whats the difference between a CRT and an LCD?

• 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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Input and Output Devices
Section D
Chapter 2
Which display device produces the best image?

• Screen size is the measurement in inches from one
  corner of the screen diagonally across to the
  opposite corner.
• Viewable image size (vis) - black border that
  makes image size smaller than size specified
• Dot pitch - a measure of image clarity
• smaller dot pitch means a crisper image
• Resolution - number of pixels a monitor can
  display

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Input and Output Devices
Section D
Chapter 2
Which display device produces the best image?
Two different resolutions
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Input and Output Devices
Section D
Chapter 2
Which display device produces the best image?

• Color depth - number of colors that can be
  displayed at one time
• Passive matrix screen - relies on timing to make
  sure the liquid crystal cells are illuminated
• Active matrix screen - updates rapidly
• essential for crisp display of animation, video
• found on newer notebooks
• SVGA - (super video graphics array) 800x600
• XGA - (extended graphics array) 1024x768

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Input and Output Devices
Section D
Chapter 2
What features should I look for in a printer?
Lexmark Printer
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Input and Output Devices
Section D
Chapter 2
What features should I look for in a printer?

• Print speed (typical 10 ppm)
• measured either by pages per minute (ppm) or
  characters per second (cps)
• color vs BW
• Duty Cycle - indication of the number of pages a
  printer can be expected to print per month
• Per-copy cost
• printers require ongoing costs including
• per copy cost is the cost of printing a page with
  an average amount of text, graphics, and color
• Warranty
• cover mechanical problems

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Input and Output Devices
Section D
Chapter 2
Whats the difference between an ink jet
printer and a solid ink printer?

• An ink jet printer is todays most popular
  printing technology.
• print head consists of a series of nozzles that
  sprays ink onto paper
• On special paper can produce photographic quality
• 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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Input and Output Devices
Section D
Chapter 2
Is a laser better than an ink jet?
LaserJet
Click to start
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Input and Output Devices
Section D
Chapter 2
Is a laser better than an ink jet?

• Laser printers use their own printer language to
  construct a page before printing it.
• Printer Control Language (PCL) - most widely used
• PostScript language - preferred by publishing
  professionals
• printer languages require 2MB - 8MB memory

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Input and Output Devices
Section D
Chapter 2
Is it easy to install a printer?

• Uses a cable to connect to one of your computers
  ports
• USB
• Parallel most common
• Serial
• Many come packaged with device driver software
  that you install following manufacturers
  direction
• Can be set to default printer using windows
  software

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Computer Hardware
Chapter 2
Chapter REVIEW

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

Page 57