Editing Expansion card (section)

==Applications==
The primary purpose of an expansion card is to provide or expand on features not offered by the motherboard. For example, the original [[IBM Personal Computer|IBM PC]] did not have on-board graphics or hard drive capability.  In that case, a graphics card and an [[ST-506]] hard disk controller card provided graphics capability and hard drive interface respectively. Some [[single-board computer]]s made no provision for expansion cards, and may only have provided IC sockets on the board for limited changes or customization. Since reliable multi-pin connectors are relatively costly, some mass-market systems such as [[home computer]]s had no expansion slots and instead used a card-edge connector at the edge of the main board, putting the costly matching socket into the cost of the peripheral device.

In the case of expansion of on-board capability, a motherboard may provide a [[serial port|single serial RS232 port]] or [[Ethernet]] port. An expansion card can be installed to offer multiple RS232 ports or multiple and higher bandwidth [[Ethernet]] ports. In this case, the motherboard provides basic functionality but the expansion card offers additional or enhanced ports.