Transcript Optical storage devices

Introduction to Information
Systems, 1st Edition
 Authors: Rainer, Turban and Potter
 Publisher: John Wiley & Sons, Inc.
 Slides by: Hellene Bankowski, Professor, Philadelphia University
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Technology Guide 1
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Technology Guide 1
Hardware
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Technology Guide Outline
 TG1.1 Introduction
 TG1.2 The Central Processing Unit
 TG1.3 Computer Memory
 TG1.4 Computer Hierarchy
 TG1.5 Input and Output Technologies
 TG1.6 General Technological Trends
 TG1.7 Strategic Hardware Issues
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Learning Objectives
 Identify the major hardware components of a
computer system.
 Describe the design and functioning of the central
processing unit.
 Describe the main types of primary and secondary
storage.
 Distinguish between primary and secondary storage
along the dimensions of speed, cost, and capacity.
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Learning Objectives (Continued)
 Define enterprise storage and describe the
various types of enterprise storage.
 Describe the hierarchy of computers
according to power and their respective roles.
 Differentiate the various types of input and
output technologies and their uses.
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Learning Objectives (Continued)
 Describe what multimedia systems are and
what technologies they use.
 Discuss the general trends in hardware
technology.
 Discuss strategic issues that link hardware
design to business strategy.
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TG1.1 Introduction
 Hardware refers to the physical equipment used
for the input, processing, output and storage
activities of a computer system.
 Central processing unit (CPU) manipulates the
data and controls the tasks performed by the other
components.
 Primary storage internal to the CPU; temporarily
stores data and program instructions during
processing.
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Hardware
 Secondary storage external to the CPU;
stores data and programs for future use.
 Input technologies accept data and
instructions and convert them to a form that
the computer can understand.
 Output technologies present data and
information in a form people can understand.
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Hardware (Continued)
 Communication technologies provide for
the flow of data from external computer
networks (e.g. the Internet and intranets) to
the CPU, and from the CPU to computer
networks.
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TG1.2 The Central Processing
Unit
 Central processing unit (CPU) performs the actual
computation or “number crunching” inside any computer.
 Microprocessor made up of millions of microscopic
transistors embedded in a circuit on a silicon chip.
 Control unit sequentially accesses program instructions,
decodes them and controls the flow of data to and from the
ALU, the registers, the caches, primary storage, secondary
storage and various output devices.
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CPU (Continued)
 Arithmetic-logic unit (ALU) performs the
mathematic calculations and makes logical
comparisons.
 Registers are high-speed storage areas that
store very small amounts of data and
instructions for short periods of time.
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How the CPU Works
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How the CPU Works (Continued)
 Binary form: The form in which data and instructions can be read by
the CPU – only 0s and 1s.
 Machine instruction cycle: The cycle of computer processing, whose
speed is measured in terms of the number of instructions a chip
processes per second.
 Clock speed: The preset speed of the computer clock that times all
chip activities, measured in megahertz and gigahertz.
 Word length: The number of bits (0s and 1s) that can be processed by
the CPU at any one time.
 Bus width: The size of the physical paths down which the data and
instructions travel as electrical impulses on a computer chip.
 Line width: The distance between transistors; the smaller the line
width, the faster the chip.
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Advances in Microprocessor
Design
 Moore’s Law is that microprocessor complexity would
double every two years as a result of the following changes:
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Increasing miniaturization of transistors.
Making the physical layout of the chip’s components as
compact and efficient as possible.
Using materials for the chip that improve the conductivity
(flow) of electricity.
Targeting the amount of basic instructions programmed into
the chip.
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Microprocessors &
Microcontrollers
 The two most common microprocessor
architectures are complex instruction set
computing (CISC) and reduced instruction
set computing (RISC).
 Microcontrollers are computer chips,
embedded in products and technologies, that
usually cost less and work in less-demanding
applications than microprocessors.
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TG1.3 Computer Memory
 Two basic categories of computer memory:
Primary storage and secondary storage.
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
Primary stores small amounts of data and
information that will be immediately used by the
CPU.
Secondary stores much larger amounts of data
and information (an entire software program, for
example) for extended periods of time.
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Memory Capacity
 Bit: Short for binary digit (0s and 1s), the
only data that a CPU can process.
 Byte: An 8-bit string of data, needed to
represent any one alphanumeric character or
simple mathematical operation.
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Hierarchy of Memory Capacity
 Kilobyte (KB): approximately one thousand bytes.
 Megabyte (MB): approximately one million bytes
(1,048,576 bytes, or 1,024 x 1,024).
 Gigabyte (GB): actually 1,073,741,824 bytes
(1,024 x 1,024 x 1,024 bytes).
 Terabyte: One trillion bytes.
 Petabyte: Approximately 1015 bytes.
 Exabyte: Approximately 1018 bytes.
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Primary Storage
 Primary storage or main memory stores three types of
information for very brief periods of time:
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Data to be processed by the CPU;
Instructions for the CPU as to how to process the data;
Operating system programs that manage various aspects of the
computer’s operation.
 Primary storage takes place in chips mounted on the
computer’s main circuit board, called the motherboard.
 Four main types of primary storage: register, random access
memory (RAM), cache memory and read-only memory
(ROM).
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Main Types of Primary Storage
 Registers: registers are part of the CPU with the
least capacity, storing extremely limited amounts of
instructions and data only immediately before and
after processing.
 Random access memory (RAM): The part of
primary storage that holds a software program and
small amounts of data when they are brought from
secondary storage.
 Cache memory: A type of primary storage where
the computer can temporarily store blocks of data
used more often.
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Primary Storage (Continued)
 Read-only memory (ROM): Type of
primary storage where certain critical
instructions are safeguarded; the storage is
nonvolatile and retains the instructions when
the power to the computer is turned off.
 Flash memory: A form of rewritable readonly memory that is compact, portable, and
requires little energy.
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Secondary Storage
 Memory capacity that can store very large
amounts of data for extended periods of time.
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It is nonvolatile.
It takes much more time to retrieve data because
of the electromechanical nature.
It is cheaper than primary storage.
It can take place on a variety of media
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Secondary Storage (Continued)
 Magnetic tape: A secondary storage medium on a
large open reel or in a smaller cartridge or cassette.
 Sequential access: Data access in which the
computer system must run through data in sequence
in order to locate a particular piece.
 Magnetic disks: A form of secondary storage on a
magnetized disk divided into tracks and sectors that
provide addresses for various pieces of data; also
called hard disks.
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Secondary Storage (Continued)
 Hard drives: A form of secondary storage that
stores data on platters divided into concentric tracks
and sectors, which can be read by a read/write head
that pivots across the rotating disks.
 Direct access: Data access in which any piece of
data be retrieved in a nonsequential manner by
locating it using the data’s address.
 Magnetic diskettes: A form of easily portable
secondary storage on flexible Mylar disks; also
called floppy disks.
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Optical Storage Devices
 Optical storage devices: A form of secondary storage in
which a laser reads the surface of a reflective plastic platter.
 Compact disk, read-only memory (CD-ROM): A form of
secondary storage that can be only read and not written on.
 Digital video disk (DVD): An optical storage device used to
store digital video or computer data.
 Fluorescent multilayer disk (FMD-ROM): An optical
storage device with much greater storage capacity than
DVDs.
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More Storage Options
 Memory cards: Credit-card-size storage
devices that can be installed in an adapter or
slot in many personal computers (i.e. memory
sticks, thumb drives).
 Expandable storage devices: Removable
disk cartridges, used as backup storage for
internal hard drives of PCs.
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Enterprise Storage Systems &
RAID
 Enterprise storage system: An independent,
external system with intelligence that
includes two or more storage devices.
 Redundant arrays of independent disks
(RAID): An enterprise storage system that
links groups of standard hard drives to a
specialized microcontroller that coordinates
the drives so they appear as a single logical
drive.
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Storage Area Networks (SANs)
 Storage area network (SAN): An enterprise
storage system architecture for building special,
dedicated networks that allow rapid and reliable
access to storage devices by multiple servers.
 Storage over IP: Technology that uses the Internet
Protocol to transport stored data between devices
within a SAN; sometimes called IP over SCSI or
iSCSI.
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Network-Attached Storage
 Network-attached storage (NAS) device is
a special-purpose server that provides file
storage to users who access the device over a
network; plug-and-play.
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TG1.4 Computer Hierarchy
 The first generation of computers, from
1946 to about 1956, used vacuum tubes
to store and process information.
 The second generation of computers,
from 1957 to 1963, used transistors for
storing and processing information.
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Computer Hierarchy (Continued)
 Third-generation computers, from 1964 to 1979,
used integrated circuits for storing and processing
information.
 Early to middle fourth-generation computers, from
1980 to 1995, used very-large-scale integrated
(VLSI) circuits to store and process information.
 Late fourth-generation computers, from 1996 to the
present, use grand-scale integrated (GSI) circuits to
store and process information.
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Computer Categories
 Supercomputers
 Mainframe Computers
 Midrange Computers
 Workstations
 Notebooks and Desktop Computers
 Appliances
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TG1.5 Input and Output
Technologies
 Input technologies allow people and other
technologies to put data into a computer. The two
main types of input devices are:
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human data-entry devices include keyboards, mouse,
trackball, joystick, touchscreen, stylus and voice
recognition;
source-data automation devices input data with minimal
human intervention (e.g. barcode reader).
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Speed up data collection;
Reduce errors;
Gather data at the source of a transaction or other event.
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Input and Output Technologies
(Continued)
 Output generated by a computer can be
transmitted to the user over several output
devices and media.

Includes monitors, printers, plotters and voice.
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Multimedia Technology
 Multimedia technology is the computerbased integration of text, sound, still images,
animation and digitized motion video.
 Merges capabilities of computers with
televisions, VCRs, CD players, DVD
players, video and audio recording
equipment, music and gaming technologies.
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TG1.6 Emerging Technologies
 Grid computing involves applying the resources of many
computers in a network to a single problem at the same time.
 Utility computing (also called subscription computing and
on-demand computing) is when a service provider makes
computing resources and infrastructure management
available to a customer as needed for a charge based on
specific usage rather than a flat rate.
 Nanotechnology refers to the creation of materials, devices
and systems at a scale of 1 to 100 nanometers (billionths of a
meter).
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TG1.7 Strategic Hardware Issues
 How do organizations keep up with the rapid price
and performance advancements in hardware?
 How often should an organization upgrade its
computers and storage systems?
 Will upgrades increase personal and organizational
productivity?
 How can organizations measure such increase?
 How do organizations manage telecommuting?
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