Inputs and Outputs

Today's computers have an almost overwhelming number of connectors and sockets that allow a wide variety of devices to exchange information with the processor. You can expect any new computer to have many of the inputs and outputs listed in Table 3.1 unless you're buying a very compact system with limited capabilities. However, some systems use several USB ports in place of the dedicated printer, mouse, keyboard, and other individual connectors.

Table 3.1: Input and Output Connectors
Open table as spreadsheet

Connector Name



AC or DC power input


Output to video display

Printer, LPT, or Parallel

Interface to a printer, scanner, or other parallel device[*]

Serial or COM

Serial data interface[*]


Interface to the public telephone network

Ethernet or LAN

Interface to Local Area Network

PS/2 Keyboard

Input from keyboard[*]

PS/2 Mouse

Input from mouse or other pointing device[*]


Input and output to Universal Serial Bus devices

IEEE 1394

Input and output to FireWire devices


Output to a television set

PC Card

Socket for a PCMCIA card (most common on laptops)


Audio input from a microphone

Line In

Audio input from a high-level source

Line Out (L & R)

Audio output to speakers (Left & Right)


Audio output to headphone


Combined inputs and outputs to a docking station or port replicator (laptops only)

Infrared or I/R

Data port for infrared data transfer (most common on laptops)

Digital Media

Socket for one or more types of flash media card

[*]Many new computers use the USB ports in place of these connectors.

The exact location of many connectors-front, back, or sides of the case-is purely a matter of convenience. As long as they work properly, the precise location of most connectors and controls makes no difference to the computer's performance. If you have a choice, look for a desktop computer with at least one or two USB connectors on the front panel; connecting and disconnecting portable devices like flash drives and digital cameras to the front panel is much easier than reaching around to the back of the case.


There are no universal symbols to identify input and output connectors. A few are commonly used among different manufacturers, but you should look in your manual for the symbols on your computer.


Look for explanations of the devices that connect to all these connectors in Parts II, III, and IV of this book.

PC User's Bible
PC Users Bible
ISBN: 0470088974
EAN: 2147483647
Year: 2007
Pages: 372

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