Computer Hardware Input Devices

Main Hardware Component Categories

• Main hardware component categories include:
  • Central Processing Unit (CPU)
  • Main memory (RAM)
  • Secondary storage devices
  • Input Devices
  • Output Devices

Input Devices

• Used to send information to the computer from outside
• Examples of input devices:
  • Keyboard
  • Mouse
  • Touch screen
  • Microphone
  • Scanner
  • Digital camera
  • Disk drive
  • CD/DVD drive
  • USB flash drive

Output Devices

• Used to send information from the computer to the outside
• Examples of output devices:
  • Computer screen
  • Printer
  • Speakers
  • Disk drive
  • CD/DVD recorder
  • USB flash drive

Central Processing Unit (CPU)

• The CPU is the hardware component that runs programs
• The CPU consists of:
  • Control Unit
    • Retrieves and decodes program instructions
    • Coordinates computer operations
  • Arithmetic & Logic Unit (ALU)
    • Performs mathematical operations

CPU's Role in Running a Program

• The CPU cycles through:
  • Fetch: get the next program instruction from main memory
  • Decode: interpret the instruction and generate a signal
  • Execute: route the signal to the appropriate component to perform an operation

Main Memory

• Holds both program instructions and data
• Main memory is:
  • Volatile: erased when the program terminates or computer is turned off
  • Also known as Random Access Memory (RAM)
  • The CPU can access data and instructions from any memory location

Main Memory Organization

• Bit:
  • The smallest piece of memory
  • Stands for binary digit
  • Holds an electrical charge (positive or negative)
• Byte:
  • Is 8 consecutive bits
  • Has an address in memory
  • There are millions (or even billions) of bytes of memory in a computer

Secondary Storage

• Non-volatile / Permanent: Holds data when the program is not running or when the computer is turned off
• Several forms of secondary storage include:
  • Disk drive: stores data magnetically
  • Optical: CD or DVD drive
  • Flash: USB flash drive

Software Programs That Run on a Computer

• System software:
  • Programs that manage the computer hardware and the programs that run on the computer
  • Examples: Operating Systems, Utility Programs, Software development tools
• Operating Systems:
  • Control the operation of the computer
  • Manage connected devices and access to storage devices
  • Allow programs to run
• Utility Programs:
  • Support programs that enhance computer operations
  • Examples: virus scanners, data backup, file compression
• Software development tools:
  • Used by programmers to create software
  • Examples: compilers, integrated development environments (IDEs)