Frequency Utilization of Regular PCI Devices Installed on the PCI-X Bus
Publication Date: 2002-Oct-23
The IP.com Prior Art Database
AbstractDisclosed is a method to operate regular/older PCI devices dynamically in PCI-X mode. Benefits include maximizing frequency without the need for hardware changes.
Frequency Utilization of Regular PCI
Devices Installed on the
Disclosed is a methodto operate regular/older PCI devices dynamically in PCI-X mode. Benefits include maximizing frequency without the need for hardware changes.
Currently, to take advantage of the PCI-X specification and capabilities, all devices attached to the PCI-X bus must be capable of PCI-X transactions. However, many motherboards only contain regular PCI devices. By default a device that is not PCI-X-aware will reduce the PCI bus speed to 33MHz or 66MHz regardless of presence of PCI-X devices.
The PCI/PCI-X switching mechanism involves the software configuration of simple hardware control digital logic that must be present on the motherboard of a PC system. The following components are required:
- The hardware of this mechanism is a few discrete TTL gates. Such logic can always be used with existing motherboard components as part of the Super I/O and/or South bridge of the main chipset (see Figure 1).
- The software is the assembly x86 instructions integrated in the system BIOS to control the hardware logic.
The disclosed method regains the PCI-X capability of the bus by isolating the on-board PCI device(s) (via software). In this way the end user can optionally disconnect the on-board regular PCI device and install a PCI-X device that runs at maximum speed. (100MHz or 133MHz).
Typically a hard reset or power cycle is required for the host PCI-bridge to switch between...