Transcript Slide 1

• Assembling an effective, efficient computer system
requires an understanding of its relationship to the
information system and the organization. The computer
system objectives are subordinate to, but supportive of,
the information system and the needs of the
organization
• Describe how to select and organize computer system
components to support information system (IS)
objectives and business organization needs
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• When selecting computer devices, you also must consider
the current and future needs of the information system and
the organization. Your choice of a particular computer
system device should always allow for later improvements
• Describe the power, speed, and capacity of central processing
and memory devices
• Describe the access methods, capacity, and portability of
secondary storage devices
• Discuss the speed, functionality, and importance of input and
output devices
• Identify popular classes of computer systems and discuss the role
of each
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Computer Systems: Integrating the
Power of Technology
• Computer system
• Special subsystem of an organization’s overall information
system
• Integrated assembly of devices used to input, process, store,
and output data and information
• Hardware
• Any machinery—most of which use digital circuits—that
assists in the input, processing, storage, and output
activities of an information system
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Hardware Components
• Central processing unit (CPU)
• Input devices
• Output devices
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Hardware Components (continued)
• Communications devices
• Primary storage devices
• Secondary storage devices
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Figure 3.1: Computer System
Components
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Hardware Components in Action
• Step 1: Fetch instruction
• Step 2: Decode instruction
• Step 3: Execute instruction
• Step 4: Store results
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Figure 3.2: Execution of an Instruction
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Processing and Memory Devices:
Power, Speed, and Capacity
• System unit: houses the components responsible for
processing—the CPU and memory
• All other computer system devices are linked either
directly or indirectly into the system unit housing
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Processing Characteristics and
Functions
• Machine cycle time is measured in:
• Microseconds (1 millionth of a second)
• Nanoseconds (1 billionth of a second)
• Picoseconds (1 trillionth of a second)
• MIPS (Millions of Instructions Per Second)
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Processing Characteristics and
Functions (continued)
• Clock speed: electronic pulses that affect machine cycle
time
• Hertz (Hz): one cycle (pulse) per second
• Megahertz (MHz): millions of cycles per second
• Microcode: elementary circuits and logical operations a
processor performs when executing instructions
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Figure 3.3: Clock Speed and the
Execution of Microcode Instructions
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Wordlength and Bus Line Width
• Bit: a binary digit (0 or 1)
• Wordlength: number of bits the CPU can process at any
one time
• Bus line: physical wiring that connects the computer
system components
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Physical Characteristics of the CPU
• CPU: collection of digital circuits
• Electrical current flows through silicon
• Moore’s Law: transistor densities on a chip double every
18 months
• Superconductivity: property of certain metals that allows
current to flow with minimal electrical resistance
• Optical processors: computer chips that use light waves
instead of electrical current to represent bits
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Figure 3.4: Moore’s Law
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Complex and Reduced Instruction Set
Computing
• Complex instruction set computing (CISC): chip
design that places as many microcode instructions into the
central processor as possible
• Reduced instruction set computing (RISC): chip
design that involves reducing the number of microcode
instructions built into a chip to an essential set of
common microcode instructions
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Memory Characteristics and Functions:
Storage Capacity
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Types of Memory
• Random access memory (RAM): temporary and volatile
• Types of RAM
• EDO (Extended Data Out)
• DRAM (Dynamic RAM)
• SDRAM (Synchronous DRAM)
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Types of Memory (continued)
• ROM (read-only memory): usually nonvolatile
• Types of ROM
• PROM (programmable read-only memory)
• EPROM (erasable programmable read-only memory)
• Cache memory
• High-speed memory that a processor can access more
rapidly than main memory
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Figure 3.5: Basic Types of Memory Chips
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Figure 3.6: Cache Memory
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Multiprocessing
• Multiprocessing: the simultaneous execution of two
or more instructions at the same time
• Massively parallel processing
• Speeds processing by linking hundreds or thousands of
processors to operate at the same time, or in parallel
• Can coordinate large amounts of data and access them
with greater speed
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Figure 3.7: Massively Parallel Processing
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Secondary Storage
• Secondary storage: offers advantages of nonvolatility,
greater capacity, and greater economy
• Access methods, storage capacities, and portability
required are determined by the information system’s
objectives
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Table 3.1: Cost Comparison for Various
Forms of Data Storage
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Access Methods
• Sequential access: retrieval method in which data must
be retrieved in order; devices used are called sequential
access storage devices (SASDs)
• Direct access: retrieval method in which data can be
retrieved in any order; devices used are called direct
access storage devices (DASDs)
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Secondary Storage Devices
• Magnetic tapes
• Magnetic disks
• Virtual tape
• Optical discs
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Secondary Storage Devices
(continued)
• Digital versatile disk (DVD)
• Magneto-optical (MO) disks
• Memory cards
• Flash memory
• Expandable storage
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Enterprise Storage Options
• Attached storage
• Network-attached storage (NAS)
• Storage area network (SAN)
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Figure 3.12: Storage Area Network
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Input and Output Devices: The
Gateway to Computer Systems
• Through input and output devices, people provide data
and instructions to computer and receive results from it
• Selection of input and output devices depends on
organizational goals and information systems objectives
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Characteristics and Functionality
• Data: can be human- or machine-readable
• Data entry: process of converting human-readable data
into machine-readable form
• Data input: involves transferring machine-readable data
into the system
• Source data automation: involves capturing and editing
data where the data is initially created and in a form that
can be directly input to a computer
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Input Devices
• Personal computer input devices
• Keyboard
• Mouse
• Voice-recognition devices
• Digital computer cameras
• Terminals
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Input Devices (continued)
• Scanning devices
• Optical data readers
• Magnetic ink character recognition (MICR) devices
• Point-of-sale (POS) devices
• Automated teller machine (ATM) devices
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Input Devices (continued)
• Pen input devices
• Light pens
• Touch-sensitive screens
• Bar-code scanners
• Radio-frequency identification (RFID)
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Output Devices
• Display monitors
• Liquid crystal displays (LCDs)
• Active-matrix
• Passive-matrix
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Output Devices (continued)
• Organic light-emitting diodes (OLEDs)
• Printers and plotters
• Computer output microfilm (COM) devices
• Music devices
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Computer System Types, Selecting,
and Upgrading
• Computers can be classified as either special purpose or
general purpose
• Special-purpose computers: used for limited
applications by military and scientific research groups
• General-purpose computers: used for a wide variety of
applications
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Computer System Types
• Handheld computers
• Portable computers
• Thin client
• Desktop computers
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Computer System Types (continued)
• Workstations
• Servers
• Mainframe computers
• Supercomputers
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Selecting and Upgrading Computer
Systems
• Hard drive considerations
• Main memory considerations
• Printer considerations
• DVD burners
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Summary
• Hardware: machinery that assists in the input,
processing, storage, and output activities of an
information system
• Hardware components include central processing unit
(CPU), input and output devices, communications
devices, primary storage devices, and secondary
storage devices
• Random access memory (RAM): temporary and volatile
• Read-only memory (ROM): usually nonvolatile
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Summary (continued)
• Multiprocessing: simultaneous execution of two or more
instructions at the same time
• Sequential access: records must be retrieved in order
• Direct access: records can be retrieved in any order
• Examples of secondary storage devices: magnetic tapes
and disks, optical disks, and DVDs
• Enterprise storage options: attached storage, networkattached storage (NAS), and storage area network (SAN)
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Summary (continued)
• Examples of input devices: keyboards, mice, voicerecognition devices, terminals, scanning devices, and
touch-sensitive screens
• Examples of output devices: display monitors, liquid
crystal displays (LCDs), printers, and plotters
• Computers can be classified as either special purpose or
general purpose
• Computer system types: handheld computers, portable
computers, desktop computers, workstations, servers, etc.
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