The PCI-SIG (PCI Special Interest Group) is the industry organization that owns and manages the PCI Local Bus specification as an open industry standard. The organization defines and implements new industry standard I/O (Input/Output) specifications as the industry's local I/O needs evolve. Currently, more than 700 industry-leading companies are active PCI-SIG members. The PCI-SIG's board of directors is composed of the following companies: AMD, Compaq, HP, IBM, Intel, Microsoft, Phoenix Technologies, ServerWorks and TI. Companies involved have now agreed on the next PCI stepping version 2.3. This new standard aimed for migration to low-voltage designs and therefore support for 5 volt-keyed add-in cards has been removed. Read more...
With vast numbers of users adopting battery-powered systems, and with system manufacturers turning to low-power designs, this latest version of the PCI specification supports both 3.3 volt and 5 volt signaling, but no longer supports the 5 volt-keyed add-in card. In addition, this latest version defines a new low profile add-in card form factor for use in small form factor system designs. According to Roger Tipley, president and chairman of the PCI-SIG, "Present semiconductor technologies have reduced voltage levels to 3.3 volts or less. While 5 volt tolerance on input signals is still desirable today to plug in older PCI cards, sub-3.3 volt signaling and 3.3 volt-tolerant inputs will be the future of PCI and PCI-X compatible devices. Eliminating support for 5 volt-only keyed add-in cards is the first step in the migration to 3.3 volt signaling systems, and ensures that PCI v2.3 compliant add-in cards will be compatible with the 3.3 volt keyed system board connectors of today and tomorrow." Support for 5 volt signaling is retained in PCI v2.3 for backward compatibility with 5 volt-keyed add-in cards, but it is expected to be eliminated in future versions of this specification, making PCI v2.3 the last PCI specification with support for 5 volt signaling. This change follows the same path as other recent PCI bus formats, including Mini PCI and PCI-X, which support only 3.3 volt signaling and 3.3 volt-keyed system board connectors. Source: PCI-SIG
With vast numbers of users adopting battery-powered systems, and with system manufacturers turning to low-power designs, this latest version of the PCI specification supports both 3.3 volt and 5 volt signaling, but no longer supports the 5 volt-keyed add-in card. In addition, this latest version defines a new low profile add-in card form factor for use in small form factor system designs. According to Roger Tipley, president and chairman of the PCI-SIG, "Present semiconductor technologies have reduced voltage levels to 3.3 volts or less. While 5 volt tolerance on input signals is still desirable today to plug in older PCI cards, sub-3.3 volt signaling and 3.3 volt-tolerant inputs will be the future of PCI and PCI-X compatible devices. Eliminating support for 5 volt-only keyed add-in cards is the first step in the migration to 3.3 volt signaling systems, and ensures that PCI v2.3 compliant add-in cards will be compatible with the 3.3 volt keyed system board connectors of today and tomorrow." Support for 5 volt signaling is retained in PCI v2.3 for backward compatibility with 5 volt-keyed add-in cards, but it is expected to be eliminated in future versions of this specification, making PCI v2.3 the last PCI specification with support for 5 volt signaling. This change follows the same path as other recent PCI bus formats, including Mini PCI and PCI-X, which support only 3.3 volt signaling and 3.3 volt-keyed system board connectors. Source: PCI-SIG
