Transcript Chapter 3

Principles of Information
Systems
Eighth Edition
Chapter 3
Hardware: Input, Processing, and
Output Devices
Principles and Learning Objectives
• Assembling an effective, efficient set of
computer hardware devices requires
understanding their role in supporting the
underlying information systems and the needs
of the organization; the computer hardware
objectives are subordinate to, but supportive of,
the information systems and the needs of the
organization
– Describe how to select and organize computer
hardware components to support information
system (IS) objectives and business needs
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Principles and Learning Objectives
(continued)
• When selecting computer hardware, you must
consider the current and future needs of the
information systems and the organization; your
choice of a hardware device should always allow
for later improvements to meet evolving
organizational needs
– Describe the power, speed, and capacity of central
processing and memory devices
– Describe the access methods, capacity, and
portability of secondary storage devices
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Principles and Learning Objectives
(continued)
– 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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Why Learn About Hardware?
• Can improve productivity, increase revenue, reduce
costs, and provide better service
• Managers are expected to know about hardware
– To help define business needs
– To ask questions and evaluate options when buying
equipment
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Introduction
• Hardware: any machinery (most of which use
digital circuits) that assists in the input, processing,
storage, and output activities of an information
system
• When making hardware decisions, businesses
must consider how the hardware can support:
– Objectives of the information system
– Goals of the organization
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Computer Systems: Integrating The
Power of Technology
• Choosing the right computer hardware requires
understanding its relationship to the information
system and needs of the organization
• Hardware objectives are subordinate to, but
supportive of, the information system and the
current and future needs of the organization
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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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Hardware Components (continued)
Figure 3.1: Hardware Components
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Hardware Components in Action
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Step 1: Fetch instruction
Step 2: Decode instruction
Step 3: Execute instruction
Step 4: Store results
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Hardware Components in Action
(continued)
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:
– 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: series of electronic pulses produced
at a predetermined rate that affects machine cycle
time
– Often measured in:
• Megahertz (MHz): millions of cycles per second
• Gigahertz (GHz): billions of cycles per second
• Microcode: predefined, elementary circuits and
logical operations that the processor performs
when it executes an instruction
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Physical Characteristics of the CPU
• Digital circuits on chips
• Electrical current flows through silicon
• Moore’s Law: transistor density of chips will
double every 18 months
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Physical Characteristics of the CPU
(continued)
Figure 3.3: Moore’s Law
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Memory Characteristics and Functions
• Main memory
– Located physically close to the CPU, but not on the
CPU chip itself
– Rapidly provides data and instructions to the CPU
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Storage Capacity
Table 3.1: Computer Storage Units
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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)
• Types of nonvolatile memory
– ROM (read-only memory)
– 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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Types of Memory (continued)
Figure 3.4: Basic Types of Memory Chips
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Types of Memory (continued)
Figure 3.5: Cache Memory
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Multiprocessing
• Multiprocessing: simultaneous execution of
two or more instructions at the same time
• Multiprocessing using coprocessors
– Coprocessor: speeds processing by executing
specific types of instructions while the CPU works
on another processing activity
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Parallel Computing
• Parallel computing: simultaneous execution of the
same task on multiple processors to obtain results
faster
• Massively parallel processing:
– Speeds processing by linking hundreds or
thousands of processors to operate at the same
time, or in parallel
– Each processor has its own bus, memory, disks,
copy of the operating system, and applications
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Parallel Computing (continued)
• Different approaches to achieving parallel
computing
– Single instruction/multiple data (SIMD) parallel
processors
– Multiple instruction/multiple data (MIMD) parallel
processors
• Grid computing: use of a collection of
computers, often owned by multiple individuals
or organizations, to work in a coordinated
manner to solve a common problem
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Secondary Storage
• Compared with memory, offers the 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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Access Methods
• Sequential access: records must be retrieved in
order
– Devices used are called sequential access storage
devices (SASDs)
• Direct access: records can be retrieved in any
order
– Devices used are called direct access storage
devices (DASDs)
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Devices
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Magnetic tapes
Magnetic disks
RAID
Virtual tape
Optical disks
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Devices (continued)
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Digital video disk (DVD)
Holographic Versatile Disc (HVD)
Memory cards
Flash memory
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Enterprise Storage Options
• Attached storage
• Network-attached storage (NAS)
• Storage area network (SAN)
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Enterprise Storage Options
(continued)
Figure 3.9: 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 the computer and receive
results from it
• Selection of input and output devices depends on
organizational goals and IS objectives
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Characteristics and Functionality
• Data can be human-readable or machine-readable
• Data entry: converts human-readable data into
machine-readable form
• Data input: transfers machine-readable data into
system
• Source data automation: 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
• Speech-recognition technology
• Digital cameras
• Terminals
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Input Devices (continued)
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Scanning devices
Optical data readers
Magnetic ink character recognition (MICR) devices
Magnetic stripe card
Point-of-sale (POS) devices
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Input Devices (continued)
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Automated teller machine (ATM) devices
Pen input devices
Touch-sensitive screens
Bar-code scanners
Radio Frequency Identification (RFID)
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Output Devices
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Display monitors
Liquid crystal displays (LCDs)
Organic light-emitting diodes (OLEDs)
Printers and plotters
Digital audio player
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Special-Purpose Input and Output
Devices
• Computer-based navigation systems
• Multiple function printers
• Eyebud screens
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Computer System Types, Selection,
and Upgrading
• 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
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Handheld computers
Portable computers
Thin client
Desktop computers
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Computer System Types (continued)
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Workstations
Servers
Mainframe computers
Supercomputers
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Selecting and Upgrading Computer
Systems
• Dispose of old equipment properly
• Consider factors such as speed, cost, and
performance when upgrading
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Hard drive
Main memory
Printer
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: central processing unit
(CPU), input and output devices, communications
devices, primary storage devices, and secondary
storage devices
• Random access memory (RAM): temporary and
volatile
• ROM (read-only memory): 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, DVDs, memory cards, etc.
• Enterprise storage options: attached storage,
network-attached 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 specialpurpose or general-purpose
• Computer system types: handheld computers,
portable computers, desktop computers,
workstations, servers, etc.
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