Transcript Chapter 4 - cda college

Management Information Systems,
Sixth Edition
Chapter 4:
Business Hardware
Objectives
• List major hardware components of computers
and explain their functions
• Classify computers into major categories, and
identify their strengths and weaknesses
• Identify and evaluate key criteria for deciding
what computers or related devices to purchase
• Discuss the possible health hazards of computer
use
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Computer Hardware Components
• Hardware: physical components of computers
and related electronic devices
• Consider software before hardware
• Computer must handle four operations:
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Accept data
Store data and instructions
Process data
Output data and/or information
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Computer Hardware Components
(continued)
• In general, every computer has the following
components:
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Input devices
Central processing unit (CPU)
Internal memory
Storage
Output devices
• Input devices: receive signals from outside of
computer and transfer them into the computer
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Computer Hardware Components
(continued)
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Computer Hardware Components
(continued)
• Central processing unit (CPU)
– Accepts instructions and data
– Decodes and executes instructions
– Stores results (output) in memory
• Internal (or primary) memory: stores data and
instructions before and after CPU processes
them
– RAM: random access memory
– ROM: read-only memory
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Computer Hardware Components
(continued)
• Motherboard: circuit board containing the CPU
and primary memory
• Storage: magnetic disks, magnetic tapes,
optical discs, DVDs, and flash memory
– Allows permanent storage
• Output devices: deliver information from the
computer to the user
– Monitors and printers are the most common
output devices
– Audio devices also deliver output
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Computer Hardware Components
(continued)
• Bit: Binary digit
– 0 or 1
• Byte: a standard group of eight bits
– Most characters can be represented by a single
byte
• Computer memory and storage capacity are
measured in megabytes (MB), gigabytes (GB),
and terabytes (TB)
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Computer Hardware Components
(continued)
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Classification of Computers
• Computers vary in size and power
• Classified by power
– Power is determined mainly by processing speed
and memory size
• More powerful computers are more expensive
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Supercomputers
• Supercomputers: most powerful computers at
any given time
– Largest in physical size and most expensive
– Designed for complex arithmetic calculations
– Generally impractical for business purposes
• Parallel processing: multiple processors
running simultaneously
– Also known as multiprocessing
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Mainframe Computers
• Mainframe computers: store large amounts of
data and business transactions
– Less expensive and less powerful than
supercomputers
– Often used by banks, universities, and insurance
companies as a central computer
– 40-50% of world’s business data resides on
mainframes
– Use multiple processors
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Midrange Computers
• Midrange computers: often act as servers
within organizations or through the Internet
– Smaller and less powerful than mainframes
– Serve hundreds of users that connect from
personal computers
– Use multiple processors
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Microcomputers
• Microcomputers: personal computers,
notebook computers, and handhelds
• Workstation: more powerful microcomputer
used for CAD, CAM, and scientific applications
• Power of microcomputers doubles about every
two years
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Computers on the Go: Notebook,
Handheld, and Tablet Computers
• Notebook (or laptop) computer: compact
personal computer powered by rechargeable
battery
– New models include wireless technology
• Personal digital assistant (PDA): handheld
computer
– Stylus: pen-like device used to enter data through
a touch screen
• Tablet computer: PC in the form of a thick
writing tablet that recognizes handwriting
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Converging Technologies
• Technology convergence: building several
technologies into a single piece of hardware
– Prominent in handheld units
• Commonly merged technologies include:
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Cell phones
Television
Digital cameras
Digital sound recorder
MP3 players
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A Peek Inside the Computer
• Professionals must know about computer
components to understand their power and
capabilities
– They use this knowledge to make good decisions
in purchasing or recommending a computer
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The Central Processing Unit
• CPU has two units to store and process data
– Control unit and arithmetic logic unit
• CPU is a silicon chip with multiple circuits
• Also known as microprocessor
• Multicore processors: processors that combine
two or more CPUs or “cores” on a single chip
• Multithreading: processing more than one
program, or several parts of a program, at the
same time
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The Central Processing Unit (continued)
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The Central Processing Unit (continued)
• Microprocessors are embedded with transistors
• Transistor: a semiconductor that can represent
binary code’s two states
• CPU machine cycle:
– Time period during which the CPU fetches,
decodes, and executes each instruction
• CPU clock: special circuitry on the processor
that synchronizes all tasks
• Clock rate: number of pulses per second
– A machine cycle takes several clock pulses
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The Central Processing Unit
(continued)
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The Central Processing Unit
(continued)
• Data word: maximum number of bits that the
control unit can fetch from primary memory in a
single machine cycle
– Current microcomputers have words of 32 or 64
bits
• Arithmetic logic unit: the part of the CPU that
performs arithmetic and logical operations
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Computer Power
• Computer power depends on processing speed
and memory capacity
• Bus: electronic lines or traces used for
communication inside computer
• Throughput: number of bits per second that the
bus can accommodate
• MIPS: millions of instructions per second, a
common measure of computer speed
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Input Devices
• Computers must receive input to produce output
• Input devices include machines and devices
used to enter instructions and data into
computer
• Common input devices include:
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Keyboard
Trackball
Microphone
Scanner
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Keyboard
• Keyboard: an input device that contains keys
that users press to enter data
– Includes letters, numbers, punctuation, and
function keys
– QWERTY: standard keyboard layout
– Dvorak: keyboard layout that allows faster typing
• Ergonomics: the study of the comfort and
safety of humans in the workplace
• Ergonomic keyboard: fits the natural position
of forearms and prevents injury
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Mouse, Trackball, and Trackpad
• Mouse: input device that controls an on-screen
pointer to facilitate point-and-click approach
– Has one to five buttons for clicking, locking,
dragging
• Trackball: similar to mouse, but user
manipulates a ball within the device to indicate
movement on the screen
• Trackpad: cursor movement is controlled by
moving a finger over a touch-sensitive pad
• Mice and similar devices can be wireless units
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Touch Screen
• Touch screen: both an input and an output
device
– Often used for public applications, such as kiosks
– Prevalent in handheld devices, GPS devices, and
mobile phones
– Allows the user to navigate and select by
touching the screen
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Source Data Input Devices
• Source data input devices: copy data directly
from sources such as bar codes, credit cards,
and checks
• Optical mark recognition devices detect
positions of marks or characters
• Optical character recognition (OCR) devices
try to interpret handwritten and printed text
• Magnetic-ink character recognition (MICR):
detects magnetic ink on checks
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Source Data Input Devices (continued)
• Magnetic strips on credit cards store encoded
data
• Bar codes on products and packages store
encoded information
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Source Data Input Devices (continued)
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Imaging
• Imaging: converts documents into images
– Saves paper
– More efficient retrieval and filing
• Scanned document images can be:
– Indexed and linked to relevant records in
databases
– Easily retrieved
• Original paper documents can be destroyed
after scanning
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Speech Recognition
• Speech (or voice) recognition: process of
translating human speech into computerreadable data and instructions
• Receives input from microphone and processes
it with software
• Speech-operated computers may increase noise
level in offices and add distraction
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Output Devices
• Output device: a device that delivers results of
computer processing
• Popular output devices include:
– Monitors
– Printers
– Speakers
• In the future, smell output is possible
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Monitors
• Pixel (picture element): small dots that make up
the images on a monitor
• Cathode-ray tube: inner side of screen has layer
of phosphoric dots that make up the pixels
– Electron gun receives instructions from computer
and sweeps the pixels
• Flat-panel monitor: advantages include lower
power use, sharper images, and slim profile
• Liquid crystal display (LCD) monitor: uses a
liquid crystal filled screen
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Monitors (continued)
• Monitor price depends on:
– Size, measured as the diagonal length of the
screen
– Brightness
– Contrast ratio (the higher the better)
– Pixel pitch (closeness of the pixels)
• Resolution: a measure of picture sharpness
– Number of pixels in the width and height of the
screen
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Printers
• Nonimpact printer: does not mechanically
impact the paper
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Laser printer is most common in business
Others include ink-jet and electrothermal printers
Speed is measured in pages per minute (ppm)
Density measured in dots per inch (DPI)
• Impact printers: reproduce image by using
mechanical impact
– Dot-matrix printer: tiny pins strike ink ribbon
against paper
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Storage Media
• Data must be stored on nonvolatile medium
– Data is retained even when the storage device is
not connected to electrical power
• Storage devices differ in the technology used to
maintain data and physical structure
• Evaluate storage devices by comparing:
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Cost
Capacity
Access speed
Access mode
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Modes of Access
• Sequential storage: data is organized one
record after another
– Must read through all records that are stored prior
to the desired record
• Direct access: records are organized by
physical address on the device
– A record can be accessed directly (randomly)
• Flash drives: small storage devices that
connect via universal serial bus (USB)
• Direct access storage media is the only practical
way to organize and query databases
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Modes of Access (continued)
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Magnetic Tapes
• Magnetic tapes: similar to tapes used in tape
recorders and VCRs, usually as cartridges
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Provide lowest cost (bytes per dollar)
Can back up all data
Takes a long time to copy from tape
Tapes are unreliable after long periods of time or
usage
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Magnetic Disks
• Magnetic disk: most widely used storage
medium
– Includes hard disks and floppy disks
• Hard disk: stack of several rigid platters
installed in the same box that holds the CPU
– Stores up to one TB of data
– External hard disks connect to computer through
USB port
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Optical Discs
• Optical disc: recorded by treating the disc
surface to reflect light in different ways
• Two basic categories of optical disk:
– Compact discs (CDs)
– Digital video discs (DVDs)
• Compact discs: available as read-only,
recordable, and rewritable
• DVDs: store 4.7 GB per side
• Optical discs are slower than hard disks
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Optical Tape
• Optical tape: uses same technology as optical
discs to store and retrieve data
• Bits are organized sequentially, similar to
magnetic tape
• Mainly used in digital video camcorders
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Flash Memory
• Flash memory: rewritable memory chip that
holds content without power
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Consumes very little power
Does not need a constant power supply
Fast access times
Relatively immune to shock or vibration
• Available as memory card and USB drive
• Solid state disk: storage media that does not
have latency time
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DAS, NAS, and SAN
• Direct access storage (DAS): disk or array of
disks or tapes directly connected to server
– Easy to deploy and manage
– Does not relieve any of server’s workload
• Network-attached storage (NAS): device
designed for networked storage
– Includes both the storage media and the software
to manage it
– Offloads processing from the server
– Highly scalable
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DAS, NAS, and SAN (continued)
• Storage area network (SAN): a network fully
devoted to storage and transfer of data
– Managed separately from the rest of the LAN
– May combine DAS and NAS devices
– Can transfer larger blocks of data at higher
speeds
– Expensive and complex to manage
• RAID: redundant array of independent disks
– Used by DAS, NAS, and SAN
– Fault-tolerant: can continue even through disk
failures due to redundancy
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Business Considerations in Evaluating
Storage Media
• When purchasing storage devices, managers
must consider:
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Purpose of data storage
Amount of data to be stored
Required speed of data storage and retrieval
Unit space and portability of the device
Cost
Reliability and life expectancy
Trade-offs
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Business Considerations in Evaluating
Storage Media (continued)
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Considerations in Purchasing
Hardware
• Companies must consider the following when
selecting equipment to purchase:
– Power of the equipment (memory size, capacity,
speed)
– Expansion slots and ports (sockets used to
connect computer to external devices)
– Monitor type and resolution
– Ergonomics
– Compatibility with existing hardware, software,
and networks
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Considerations in Purchasing
Hardware (continued)
• Considerations (continued):
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Hardware footprint (physical size of equipment)
Reliability of vendor
Warranty policy and post-warranty support
Power consumption and noise
Cost
• Backward compatibility: the capability to work
with older hardware or software
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Scalability and Updating Hardware
• Scalability: resources can be expanded or
upgraded to provide increased power
• Not all hardware is scalable
• Leasing hardware is a valid option to avoid short
useful lifetime of hardware
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Summary
• Understanding hardware is important for
purchasing decisions
• Computers are classified according to power
• All computers have a CPU to process
instructions
• Clock rate measures the speed of a CPU
• Data word: the number of bits the computer can
process in a single cycle
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Summary (continued)
• Computer power: measured by its speed,
memory size, and number of processor cores
• RAM: volatile memory that forms the largest part
of computer’s memory
• ROM is nonvolatile; it does not require power
• Imaging devices help process text and graphics
• When evaluating external storage, consider
transfer rate, capacity, portability, and form of
data organization supported
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Summary (continued)
• Data is organized sequentially on tapes
• Direct access storage devices such as RAM,
magnetic disks, and optical discs allow random
access
• Databases require direct access storage devices
• When purchasing hardware, professionals
should consider cost, power, scalability, and
compatibility
• Information technology may pose health risks
such as carpal tunnel syndrome
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