"
Super I/O" is a class of I/O controller
integrated circuits that began to be used on
personal computer motherboards in the late
1980s, originally as add-in cards, later embedded on the motherboards. A super I/O chip combines interfaces for a variety of low-
bandwidth devices. The functions provided usually include:
A super I/O chip may also have other interfaces, as for a
joystick or
infrared port. By combining many functions in a single chip, the number of parts needed on a motherboard is reduced, thus reducing the cost of production.
The original super I/O chips communicated with the
central processing unit via a connection with an
Industry Standard Architecture (ISA) bus. With the evolution away from ISA towards use of the
Peripheral Component Interconnect (PCI) bus, the Super I/O chip was often the biggest remaining reason for continuing inclusion of ISA on the motherboard.
Modern super I/O chips use the
Low Pin Count (LPC) bus instead of ISA for communication with the CPU. This normally occurs through an LPC interface on the
southbridge chip of the motherboard.
Companies that make super I/O controllers include Fintek, ITE, SMSC,
United Microelectronics Corporation (UMC) and
Winbond Electronics Corporation.
National Semiconductor used to make them but sold that business to Winbond in 2005.
