What is PCI-104?
The PCI-104 specification was introduced by the PC104 Embedded Consortium. PCI-104 is identical to the widely used PC104 plus combined ISA and PCI embedded standard except that the PC104 AT and XT connectors for the ISA bus are removed. Eliminating the large ISA bus connector gives an additional 10% of board area for either larger CPU chipsets, higher levels of integration, and/or I/O connectors. The PCI-104 specification still maintains the small 3.550 x 3.775-inch size, rugged design, and self-stacking architecture for embedded applications set by the PC104 Plus standards. It can also be offered in a fan less solution. While the current PC104 and PC104 Plus standards will retain the ISA bus and support the large existing base of PC104 add-on modules, the PCI-104 specification defines a standard with PCI-compatible I/O features which allows video, audio, Ethernet, and contemporary communications to be handled on the single board computer.
PCI-104 is the terminology used for the PCI-only (32-bit PCI bus) specification within the PC/104 product family. PC/104 supports the ISA bus with a 104-pin connector, and PC/104-Plus supports ISA and PCI through separate connectors. PCI-104 eliminates the on-board support for the ISA bus, retaining only the 120-pin connector for PCI. ISA support may still be obtained through use of a PCI to ISA bridge. Because PCI is gradually replacing ISA as the bus of choice for device designs, the need for the ISA connector on the PC/104-Plus architecture is declining. The PCI-104 specification was adopted in 2003 by the PC/104 Consortium. The specification provides an industry standard for PC/104 footprint compatible devices that offer PCI, but not ISA bus connections. By not including the ISA connector, a small PC/104 format board regains space that can be used to provide additional functionality. Answer submitted by Michele Lukowski at VersaLogic Corp. Return to the table of contents.
