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Definition: PC input/output
Every peripheral device (keyboard, modem, monitor, etc.) requires a control circuit that interfaces with the computer's processor (CPU). These circuits are either built into the chips on the motherboard or are contained on plug-in cards. See chipset.
On the Motherboard
A fully equipped PC motherboard has built-in controller circuits for all the basic peripheral devices. It has sockets to plug in internal drives (storage drive and CD/DVD drive) and ports for external devices: keyboard, mouse, monitor and network. Audio output may comprise a single 3.5mm Line Out port or multiple ports for surround sound (see PC audio ports).
Via Plug-In Cards
Additional input/output can be added by plugging in controller cards into the motherboard's PCI or PCI Express slots. For example, a higher-quality graphics card can be plugged in, and the built-in display circuit can be disabled (see GPU). See PCI and BIOS.
Peripheral Drivers
Legacy Interfaces
On the Motherboard
A fully equipped PC motherboard has built-in controller circuits for all the basic peripheral devices. It has sockets to plug in internal drives (storage drive and CD/DVD drive) and ports for external devices: keyboard, mouse, monitor and network. Audio output may comprise a single 3.5mm Line Out port or multiple ports for surround sound (see PC audio ports).
Via Plug-In Cards
Additional input/output can be added by plugging in controller cards into the motherboard's PCI or PCI Express slots. For example, a higher-quality graphics card can be plugged in, and the built-in display circuit can be disabled (see GPU). See PCI and BIOS.
All peripherals require driver software, which enables the OS to command the hardware. When a peripheral device is added that is new to the computer, a controller card is plugged in, and a driver is installed.
These peripheral interfaces were found on earlier PCs. If a device requires a mouse, keyboard or serial port, adapters are available that convert them to USB. See legacy port.