Pci Express Root Port Function - TYAN Tomcat i925X S5130 User Manual

Tomcat i925X S5130

3.5.1 PCI Express Root Port Function

This option enables the BIOS to detect the PCI devices attached to the four PCI Express ports.
PCI Express is the third generation high performance I/O bus used to interconnect peripheral
devices in applications such as computing and communication platforms. The first generation
buses include the ISA, EISA, VESA, and Micro Channel buses, while the second generation
buses include PCI, AGP, and PCI-X. PCI Express is an all encompassing I/O device
interconnect bus that has applications in the mobile, desktop, workstation, server, embedded
computing and communication platforms.
To improve bus performance, reduce overall system cost and take advantage of new
developments in computer design, the PCI Express architecture had to be significantly re-
designed from its predecessor buses. PCI and PCI-X buses are multi-drop parallel
interconnect buses in which many devices share one bus.
PCI Express on the other hand implements a serial, point-to-point type interconnect for
communication between two devices. Multiple PCI Express devices are interconnected via the
use of switches, which means one can practically connect a large number of devices together
in a system. A point-to-point interconnect implies limited electrical load on the link allowing
transmission and reception frequencies to scale to much higher numbers. Currently PCI
Express transmission and reception data rate is 2.5 Gbits/sec. A serial interconnect between
two devices results in fewer pins per device package, which reduces PCI Express chip and
board design cost and reduces board design complexity. PCI Express performance is also
highly scalable. This is achieved by implementing scalable numbers for pins and signal lanes
per interconnect based on communication performance requirements for that interconnect.
However, PCI Express is software backwards compatible with existing PCI systems. In fact, a
PCI Express system will boot an existing OS with no changes to current drivers and
application programs. Even PCI/ACPI power management software will still run.
PCI Express Slots 1-2
When enabled, the BIOS checks these ports to detect and activate the PCI devices connected
to them.
When set to Auto, the BIOS auto determines whether to enable or disable them, depending on
whether PCI devices have been connected.
Auto / Enabled / Disabled
PCI-E Compliance Mode
This BIOS option determines compatibility between PCI-Express specification v1.0 and PCI-
Express specification v1.0a.
V1.0a / V1.0
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Chapter 3: BIOS Setup