Computer Hardware And Software

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Chapter 3

• Computer Hardware And Software

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Hardware vs. Software

• Hardware
• The physical equipment used to process
  information
• Software
• Instructions that, with the help of people,
  command the hardware to perform desired tasks

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Computer Hardware Conceptual Overview
Figure 3-1
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Computer Devices

• Processing hardware
• Controls the peripheral devices, as directed by
  computer software
• Data bus
• Electrical connection managing the flow of data
  between the processing hardware and the rest of
  the computer

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Computer Devices

• Adaptors (controllers)
• Reside inside the computer and convert commands
  and data from the data bus into signals that
  peripheral devices can use
• Port
• A connection between the computer box and a
  device outside the computer

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Computer Devices

• Input, output, and communications devices
• Transfer data between a computer and its users or
  other computers
• Storage devices
• Save data for later processing

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Uses of Input Hardware

• Active data entry
• A person uses an input device to enter data into
  a computer
• Passive data entry
• The computer obtains information without the
  active participation of a user
• Control
• A person uses an input device to control the
  tasks or actions of the computer.

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Input Devices

• Keyboard
• Consists of a plastic or metal housing containing
  keys that, when pressed, send a signal to the
  computer
• Pointing devices
• Allow the user to control the movement of a
  cursor (pointer) on the screen

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Input Devices

• Formatted Text Readers
• Read text formatted specifically for the device
  in use
• Image Capture Devices
• Include scanners, digital still cameras, and
  digital camcorders

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Input Devices

• Instrumentation devices
• Receive input through other devices, such as
  machines and musical instruments, that produce
  electrical output
• Sensors
• Devices that respond to the environment with a
  signal that a computer can interpret

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Processing Hardware The Execution Cycle
Figure 3-5
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Measuring Processing Power

• Word length and bus width
• Speed of arithmetic
• Instruction speed
• Instruction set
• Pipelining

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Processing Hardware

• Parallel processing
• Uses two or more processors in a single computer
  
• Specialized processors
• Processors, such as video accelerators, voice
  processors, cryptographic coprocessors, and DSPs,
  that perform highly specialized tasks

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Processing Trends

• Moores Law
• A 1965 prediction by Gordon Moore, a co-founder
  of Intel, that the amount of information storable
  in a square inch of silicon would double about
  every 18 months

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Types of Storage Hardware

• Primary storage
• Electrical, resides on the bus, and is directly
  accessible to the processor
• Secondary storage
• Storage that the processor cannot access directly

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Types of Storage Hardware

• Volatile storage
• Requires electrical power to retain its data
• Non-volatile storage
• Retains its data in the absence of electrical
  power

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Primary Storage Devices

• Cache memory
• Expensive super-fast primary storage
• RAM (random access memory)
• Volatile primary storage
• ROM (read-only memory)
• Non-volatile primary storage

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Secondary Storage Devices

• Fixed media
• Hard disk
• RAID
• Removable media
• Includes diskettes, cartridge disks, magnetic
  tape, optical media, and flash memory

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Other Storage Technologies

• Distributed Storage
• Storage Area Networks (SANs)
• Volumetric Storage
• Holographic
• MFD

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Hardware for Data Output

• Softcopy
• Output on an unmovable medium, such as a computer
  screen.
• Hardcopy
• Output on a medium, such as paper, that can be
  removed from the computer.
• Robotic
• Output into devices that physically move in
  response to signals from a computer.

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Types of Software - Overview
Figure 3-12
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Types of Software

• Vertical application software
• Performs tasks common to a specific industry, or
  a function within an industry
• Horizontal application software
• Addresses tasks that are common to users in all
  or almost all industries

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Types of Software

• Systems Software
• Performs tasks to manage the devices and
  resources of a computer and its network
• Systems-development software
• Used to create new software

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Vertical Software Issues

• Make vs. Buy
• Custom
• Customized
• Packaged (COTS)
• Integration
• Enterprise Resource Planning (ERP)
• Middleware

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Horizontal Software Types

• Office Automation
• Business Function Application
• Examples Sales force management, Human resources
  management, Inventory management, Bookkeeping

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Systems Software

• Operating System Kernel
• Systems Utilities
• Network and Systems Management Software

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Systems Development Software Language
Differences

• Language Translation Method
• Interpreted
• Compiled
• Level of Abstraction
• Procedural vs. Non-Procedural
• Command/Data Oriented vs. Object Oriented

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A Layered View of Software

• Client/Server model
• Divides a software application into at least two
  separate but interdependent parts called the
  client and the server

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Client/Server Models

• Two-tiered model
• Client responsible for user interface
• Server responsible for data storage and
  management
• Result Clients often need lots software and
  storage -- fat clients

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Client/Server Models

• Three-tiered model
• Client User interface
• 1st Tier Server Business logic
• 2nd Tier Server Data handling
• Results in thin clients
• Multi-tiered models
• Divide application into many components, each of
  which can call on the others to perform services

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Peek Into The Future Nanotechnology

• Nanotechnology
• Refers to building structures on a scale of
  one-billionth of a meter, about five times the
  diameter of a carbon atom
• Nanobots
• Nanometer-sized robots, able to perform
  nano-assembly under the direction of a computer
  perhaps able to reproduce

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Peek Into The Future Artificial Intelligence

• Rule-based systems
• One in which the computer makes decisions based
  on logical rules
• Neural network
• Approach to artificial intelligence that operates
  by mimicking the human brain

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Peek Into The Future Artificial Intelligence

• Evolutionary algorithms
• Approach to artificial intelligence that operates
  by observing the success or failure of millions
  of different sets of rules and approaches to
  solving a problem

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End of Chapter 3

• Computer Hardware And Software