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The IOC3 is a custom chip developed by SGI. It's being used in Origin 200, Origin 2000, Onyx 2, Octane systems, on a 32-bit PCI card which support [Dual Address Cycle] and on the MENET XIO card.


The implementation of the IOC3 PCI configuration space violates the PCI specification severly by only partially decoding the configuration address space. Only Type 0 config cycles are supported. These limitations mean the IOC3 code needs special support in the PCI hostbridge driver.


The MENET card is an XIO card used in Origin and Octane systems. Interfacing to the host system via XIO it contains 4 IOC3 chips; 3 of them have serial interfaces connected accessible via 6 mini-DIN serial connectors.

PCI card

The IOC3 PCI card is a short PCI card. Featuring PCI Dual Address Cycle support it can access the entire 64-bit address space. The IOC3 chip derives internal clocks from the PCI bus clock. It therefor will only work properly in 33MHz PCI busses.