csc chap2

• System unit


  Contains the system's electronic components and selected secondary storage devices (pen drive, cd, disk, etc.)
• System unit types


  • Desktops
  • Laptops
  • Tablets
  • Smartphones
  • Wearables
• Desktops


  • System unit is in a separate case
  • Tower Units
  • All-in-Ones (all components including monitor)
• Laptops


  • Portable and much smaller
  • Ultrabooks (laptop and tablet in one)
  • Gaming (high end graphics)
• System board


  Controls communication for the entire computer system
• Sockets


  Connection point for chips
• Chips


  Tiny circuit boards etched onto squares of silicon, also called silicon chip, semiconductor, or integrated circuit
• Slots


  Provide a connection point for specialized cards or circuit boards, provide expansion capabilities
• Bus lines


  Connecting lines that provide pathways to support communication among electronic components
• Microprocessor


  Central Processing Unit (CPU) or Processor, an integrated circuit that contains all the functions of a central processing unit of a computer
• Microprocessor


  • Control unit (tells the computer system how to carry out a program's instruction)
  • Arithmetic-logic unit (ALU) (performs arithmetic and logical operations)
• When user starts a program


  Its instruction transfer from a storage device to memory
• Data needed by programs


  Enters memory from either an input device or a storage device
• The control unit


  Interprets and executes instructions in memory, and the ALU performs calculations on the data in memory
• Resulting information


  Is stored in memory, from which it can be sent to an output device or a storage device for future access
• Processor Machine Cycle


  1. Fetch

  2. Decode

  3. Execute

  4. Store
• Word size


  The number of bits that can be processed at one time: 16, 32 or 64 (1 byte = 8 bits)
• Clock speed


  Processing speed or the number of times the CPU fetches and processes data or instructions in a second, measured in gigahertz (GHz)
• Multicore Processors


  • Two or more separate and independent CPUs within a system unit
  • Quad-core supports 4 core processes
  • Parallel Processing (computer's ability to divided tasks into parts that can be distributed across each core)
• Coprocessors


  Designed to improve specific computing operations, e.g. Graphics Processing Unit (GPU) / Graphics coprocessors
• Types of memory


  • RAM (Random Access Memory)
  • ROM (Read Only Memory)
  • Flash Memory
• Volatile memory


  Loses its contents when power is turned off, e.g. RAM, cache memory, virtual memory
• Non-volatile memory


  Does not lose contents when power is removed, e.g. ROM, flash memory
• Cache memory


  Stores copies of the data from frequently used main memory locations
• RAM


  Holds programs and data that the CPU is presently processing, volatile or temporary - contents are lost when computer is powered off
• Virtual Memory


  A memory management capability that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage
• Memory addresses


  Each location in memory has an address
• Memory size


  Measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB)
• Virtual Memory


  A memory management capability that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from random access memory (RAM) to disk storage
• Memory address


  Each location in memory has an address
• Read-only memory (ROM)


  Information stored by the manufacturer, non-volatile and cannot be changed, CPU can read but cannot change
• ROM


  • Stores instructions required to start a computer, contains special instructions to start the computer, access memory, and handle keyboard input
• Flash memory


  Combines features of RAM (can be updated) and ROM (non-volatile), contains startup information like BIOS, amount of RAM, and type of connected devices
• Expansion cards


  • Graphics cards
  • Network interface cards (NIC)
  • Wireless network cards
  • SD cards
• Bus


  Pathway for bits representing data and instructions, connects parts of the CPU to each other and other components
• Bus width


  Number of bits that can travel simultaneously down a bus
• Types of buses


  • System bus (connects CPU to memory)
  • Expansion bus (connects CPU to other components)
• Expansion buses


  • Universal Serial Bus (USB)
  • FireWire
  • PCI Express (PCIe)
• Ports connect external devices directly to the system board or to cards inserted into slots on the system board
• Types of ports


  • Standard ports
  • Specialized ports