Computing%20Basics

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Computing Basics

• Chapter 3,
• Exploring the Digital Domain

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Computing Basics
In this chapter you will learn about . . .

• how computers process information
• how hardware is organized for instruction-executio
  n
• how software directs processing
• the role of the operating system
• how the OS manages files, user interface
• common features of application software

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Computer System

• a computer system is an electronic digital data
  processing machine
• data -- symbolic representation of information
• a computer process is sequence of states during
  which data is modified in specific ways
• a program is a sequence of instructions that
  direct a process

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Instruction-Execution Cycle

• fetching the next instruction
• decoding (or interpreting) that instruction
• executing what the instruction prescribes

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Computer System

• HARDWARE
• devices, equipment
• SOFTWARE
• programs

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Processor System
stores both data and instructions used for
processing
interconnections
manages the instruction-execution cycle
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Memory

• information (data) is stored in uniform-sized
  units
• each unit has a unique address
• reading from memory
• copy data from a memory location
• writing to memory
• moving data into a memory location

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Secondary Memory and I/O

• Secondary memory
• nonvolatile storage
• cheaper, mass storage
• Input/Output devices
• input--translates human-readable forms of
  information to machine-readable data
• output-- translates machine-readable data to
  human-readable forms

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Software

• programs
• written using programming languages (symbolic
  codes for expressing computer instructions)
• programs ? processes
• conditional processing
• the ability to alternative actions based on the
  recognition of changing conditions

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Conditional Processing
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Operating Systems
An operating system is a collection of resident
programs that manage the computers resources,
supervise the execution of processes, and
provides useful services and security.

• continuous control of system
• supervises processes
• creates useful abstractions for users
• defines computing experience

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Managing Files

• A file is a sequence of items treated as a unit
  and identified with a unique name
• filenames are composed of
• identifier . extension
• identifier (Windows) up to 255 symbols
  excluding special characters
• extension (Windows) 1 - 4 characters that are
  used to classify file

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Hierarchical File System

• directory structure--series of levels based on a
  tree
• files, folders
• path--list of all ancestors of a file/folder from
  root
• pathname--conventional listing of path

• tree--special type of graph
• nodes, edges (links)
• parent(s)
• child(ren)
• ancestor(s)
• descendant(s)

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Windows Example
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User Interface

• TEXT-BASED
• command line interpreters
• terse, but powerful
• steeper learning curves
• burden of communication on user

• GRAPHIC USER INTERFACES (GUI)
• manipulate visual elements
• user-friendly
• more tedious

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Applications

• are restricted to a specific problem domain
• have a user interface based on some intuitive
  metaphor
• use conducted in sessions