3GIO -- 3rd Generation IO. A High Speed Data Bus from Intel intended to replace PCI commencing in the 2003-2004 time period. In early 2003, 3GIO was finalized and renamed PCI-Express.

The 3GIO concept does not include hot swapping and other capabilities expected on external data links. Initial plans in 1999 called for initial release in 2003; a ten year lifetime, eventual support to at least 10GHz data rates, and "transparent" convertibility from metal wiring to fibre optic at the high speed end of its range. 3GIO was intended to compete with AMD's Hyperbus. As of the 3rd Quarter of 2001, industry support for Hyperbus was fading.

3GIO is to use paired, unidirectional, serial lines. 3GIO will be quite dissimilar to PCI -- a wide parallel technology. Depending on implementation details, 3GIO probably will need to run at 16 to 32 times the speed of PCI to attain the same data bandwidth. i.e. a 1GHz 3GIO bus connection will likely be roughly equivalent to a 66MHz PCI bus connection. There is discussion of including multiple serial lines in 3GIO in order to obtain more satisfactory bandwidths.

3GIO was also known as Serial PCI and Arapahoe as well as PCI 3.0 at various times in its development.

As of late 2003, it appears that 3GIO/PCI-Express is still several years in the future. Current projections is that the first Operating System support for PCI-Express may be in a Windows version codenamed "Longhorn" that may start shipping in the 2005-2006 timeframe.

For a discussion of PCI-Express architecture as of mid 2003, see http://www.anandtech.com/systems/showdoc.html?i=183

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