Chapter 1

• Computers


  Designed to do any job that a program tells them to
• Program


  Set of instructions that a computer follows to perform a task referred to as software
• Programmer


  Person who can design, create, and test computer programs aka soft ware developer
• Hardware

  The physical devices that make up a computer
• Typical major computer components


  • Central processing unit
  • Main memory
  • Secondary storage devices
  • Input and output devices
• Central processing unit (CPU)


  The part of the computer that actually runs programs
• Microprocessors


  CPUs located on small chips
• Main memory

  Where computer stores a program while program is running, and data used by the program
• Random Access Memory (RAM)


  Main memory that the CPU is able to quickly access
• Volatile memory


  Used for temporary storage while program is running, contents are erased when computer is off
• Secondary storage


  Can hold data for long periods of time, programs normally stored here and loaded to main memory when needed
• Types of secondary memory

  • Disk drive
  • Solid state drive
  • Flash memory
• Input


  Data the computer collects from people and other devices
• Input device


  Component that collects the data
• Output


  Data produced by the computer for other people or devices
• Output device


  Formats and presents output
• General categories of software

  • Application software
  • System software
• Application software


  Programs that make computer useful for everyday tasks
• Application software


  • Word processing
  • Email
  • Games
  • Web browsers
• System software


  Programs that control and manage basic operations of a computer
• Types of system software


  • Operating system
  • Utility program
  • Software development tools
• Operating system


  Controls operations of hardware components
• Utility program


  Performs specific task to enhance computer operation or safeguard data
• Software development tools


  Used to create, modify, and test software programs
• Bit


  Electrical component that can hold positive or negative charge, like an on/off switch
• Byte


  Just enough memory to store a letter or small number, divided into eight bits
• Binary numbering system


  Computers use to represent data
• ASCII


  Most important coding scheme to represent characters as binary numbers
• Unicode


  Coding scheme becoming standard, compatible with ASCII and can represent characters for other languages
• Two's complement


  Encoding scheme used to represent negative numbers
• Floating-point notation


  Encoding scheme used to represent real numbers
• Digital


  Describes any device that stores data as binary numbers
• Pixel


  Unit that makes up a digital image
• Sample


  Unit that makes up digital music
• Machine language


  Instructions written in binary numbers that the CPU understands
• Instruction set


  Set of machine language instructions that a particular CPU brand understands
• How a program works

  1. Fetch instruction from memory

  2. Decode instruction

  3. Execute instruction
• Assembly language


  Uses short words (mnemonics) for instructions instead of binary numbers, easier for programmers to work with
• Assembler


  Translates assembly language to machine language for execution by CPU
• Low-level language


  Close in nature to machine language, like assembly language