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- 25 Aug 2004
"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.
- A floppy disk controller
- A parallel port (commonly used for printers)
- One or more serial ports
- A keyboard and mouse interface.
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.