A controller card is a type of computer hardware component that is installed on a computer motherboard. It allows the motherboard to interface with and control other components, such as disk drives, hard drives, printers, and input devices. Older computers often required a separate controller card to be installed with any new hardware component or peripheral. Today, most computers have all the necessary controllers installed on the motherboard as part of the chip set, but some add-on components may still require the installation of a separate controller card.
Every hardware component of a computer requires a controller. Any computer will have all the controllers necessary to operate all of its components installed. Many computers will include many standard controllers that will operate a number of standard devices, as manufacturers adhere to interface standards for these devices. This means that a new device installed on a computer will rarely require the addition of a controller card. Controller cards are designed to plug into a computer motherboard, usually into a type of interface called a peripheral component interconnect (PCI) slot.
Some devices, however, like certain hard drives may require a controller card. Several different types of hard drives are available on the market today. If a hard drive is added to a computer that is of a different type than the original drive, a controller card for the new drive will be necessary.
One type of controller card that has become obsolete because of advances in computer technology is the network controller card. On older computers, a separate card was required to control the device that enabled a computer to connect to and operate on a local network. Newer computers have this controller installed as part of the chip set.
Hobbyists and others wishing to upgrade older computers will often need a controller card when adding a new device or upgrading devices such as optical drives or hard drives. Network controllers, universal serial bus (USB) controllers, and hard drive controllers are some of the most common controller cards needed in these situations. Many manufacturers still produce them for use in older computers, even though these components are gradually becoming obsolete.