When dealing with computers, autodetection is a general term that relates to the ability of software or hardware to find changes to a computer system. Most commonly, autodetection refers to a system in which a computer’s basic input and output services (BIOS), operating system or buses can automatically identify when a new piece of hardware has been attached to the computer. This can be internal hardware such as random access memory (RAM) chips or an external device such as a printer, although the detection method might be different in each instance. Autodetection also can be used to describe the process in which software automatically scans newly introduced files, archives or other media to determine whether any immediate action is required, as can occur when a compact disk (CD) is inserted into a drive.
Over the course of many years of development, autodetection has undergone several changes and passed through a number of standards until eventually reaching a stable implementation. An old standard was known as plug-and-play and, although the standard eventually was abandoned, the term remains a synonym for hardware autodetection. Devices that are attached to a computer through a universal serial bus (USB) or a FireWire® cable often are called hotplugs, indicating the device is active when plugged in.
When the internal components of a computer are modified, most often the system BIOS will automatically detect the new hardware and adjust internal information accordingly. This does not remove the need for a user to supply appropriate software drivers for the hardware, but it does remove the need for other laborious tasks, such as setting switches on the motherboard. Autodetection can occur in a number of ways, but most often involves receiving a signal through one of the buses on the motherboard. If new internal hardware is incompatible with a computer system, or if it is installed incorrectly, the result very often is a malfunction during startup that will prevent the computer from booting properly. With certain devices, such as hard drives or disk drives, the hardware frequently is automatically assigned a letter designation during startup so it can be identified within the operating system.
Hotplug devices that use a USB or FireWire® cable to connect to a computer can be attached and detected after the computer is already running. A signal is sent to the computer indicating that a new device has been connected. The operating system or BIOS can then enter discovery mode, where it will poll the new hardware and receive some type of information back about what the new hardware is. At this point, the user can supply drivers to operate the new software, or the operating system can be allowed to search for the correct drivers or install generic drivers so the device can be used. Some non-standard, older or differently designed hardware might not be discoverable, in which case other procedures need to be followed for installation.