PC card sockets are like VGA output port of the notebook computer standard equipment. PC card belongs to an industrial standard (PCMCIA specification), so that it is also widely used in many medium-sized digital equipment and industrial control equipment. Before plug-and-play ports such as USB and IEEE1394, the PC card slot was the only port on a laptop that truly supported plug-and-play, and because of the widespread support for the PCMCIA specification, there were numerous PC card products on the market, providing a wide variety of expansion options for laptops.
