4.6 Expansion Cards, Bus Lines, & Ports

1) Expansion cards are circuit boards that provide more memory or that control peripheral devices (for graphics, sound, video, network interface, wireless connection, etc.).

Expansion Cards: If a computer uses closed architecture, no expansion  cards can be added; if the computer uses open architecture, expansion cards can be inserted in expansion slots inside the computer, connected to the motherboard.

2) Buses connect the expansion cards to ports.

An expansion bus is not the same as the frontside bus:

•Frontside bus: The bus that connects the CPU within itself and to main memory.

•Expansion bus: Buses that connect the CPU with expansion slots on the motherboard and thus via ports with peripheral devices.

Types of expansion buses:

•PCI: High-speed bus that has been widely used to connect PC graphics cards, sound cards, modems, and high-speed network cards.

•PCI Express: Doubles the speed of the original PCI bus . PCIe is the latest standard for expansion cards available on mainstream personal computers.

•Accelerated Graphics: Transmits data at twice the speed of a PCI bus and is designed to support video and 3-D graphics.

•Universal Serial Bus (USB): Does away with the need to install cards in expansion slots. USB devices can connect one to another outside the system unit, and then the USB bus connects to the PCI bus on the motherboard.

Firewire: Resembles the USB bus but is used for more specialized purposes, such as to connect audio and video equipment to the motherboard.

3) A port is a connecting socket or jack on the outside of the computer unit or device into which are plugged different kinds of cables that connect peripheral devices.

Port Type

  Serial port               Used to transmit data slowly over long distances          

         sSends data sequentially, one bit at a time

                                    sUsed to connect older keyboards, mouse, monitors, dial-up                                       modems

  Parallel port            For transmitting data quickly over short distances

         sTransmits 8 bytes simultaneously

         sConnects printers, external disks, tape backups

  USB port                  Universal Serial Bus high-speed hardware standard for interfacing                                    peripheral devices,   such as scanners and printers, to computers                                    without a need for special expansion   cards or other hardware                                          modifications to the computer. USB is replacing many varieties   of                                  serial and parallel ports.

FireWire                    Intended for multiple devices working with lots of data and requiring                                  fast transmission   speeds, such as DVD drives, digital video                                                cameras, and gaming consoles.

Ethernet                        Supports a network standard for linking a wired local area network                                      and connecting it to a   DSL or a cable modem for high-speed                                              Internet access.

Graphics                       Connects digital monitors and multimedia digital devices, such as                                       TVs and DVD players.

eSATA                           External Serial Advanced Technology Attachment; allows the                                               attachment of an eSATA hard   disk, which has fast data transmission                                 speeds.

Bluetooth                     Connects devices that use short-range radio waves that transmit up                                    to 30 feet.

IrDA                         Transfers data via infrared light waves between directly aligned                                           devices, as between a   smartphone and a desktop computer.

HDMI                       High-Definition Multimedia Interface; carries both video and audio                                      signals and is used for   connecting HDTVs, DVD players, and game                                    consoles to computers, laptops, and other   devices.

MIDI                             Musical Instrument Digital Interface; used to connect electronic                                          musical instruments to a   sound card that converts the signals to                                        digital instructions that can be saved or   manipulated.