Computers are your Future Chapter 2

How Computers Represent Data Bit Single circuit Binary digits 0 = no current/off 1 = current/on Binary numbers Series of binary digits Byte Group of 8 bits Represents on character of data Term Bytes Kilobyte 1 thousand Megabyte 1 million Gigabyte 1 billion Terabyte 1 trillion

How Computers Represent Data Other Codes ASCII Minicomputers PC Computers making info available online EBCDIC Low to high ordered Punctuation – lowercase letters – uppercase letters - numbers Unicode Represents more characters Great of eastern languages Hexadecimal Uses numbers 0-9 Uses letters A-F Each hex represents four binary digits 100 Binary = 01100100 Hexadecimal = 64

They System Unit System Unit: box-like case that houses hardware components Footprint: amount of space used by a device Tower case: case designed to sit on the floor next to a desk Minitower: smaller tower with less internal room Form factor: specification for how internal components (like motherboard) are mounted inside the system unit.

Inside the System Unit Motherboard: circuit board to which all other components are connected. Contains CPU (brain of the computer) Power supply: transforms AC power from outlet to DC power needed for computer operation Cooling fan: keeps computer from heat damage Internal speaker: beeps with start-up or errors Drive bays: accommodates disk drives Expansion slots: allows expansion

Memory The chip in the motherboard that retains instructions and data to be accessed by the CPU RAM Random Access Memory Volatile (not permanent) Deleted when computer is shut off Cache Memory Stores frequently used data Passwords, usernames, etc. ROM Read Only Memory Nonvolatile (permanent)

Outside the Box Connectors Thumbscrews: attach plug with small screws USB Ports: Eliminates the need for specific ports for individual devices Plug-and-play: automatically configures the system when plugged in FireWire: similar to USB for Apple Video Connectors VGA (Video Graphics Array) DVI (Digital Visual Interface)

Outside the Box Connectors (being replaced with USB) Serial ports: early ports used for dial-up to create two-way communication Parallel ports: connect printers PS/2: connect keyboards SCSI: connect printers, scanners, cameras, etc. in a daisy chain series