Introduction

PC compatibility remains important in many operating environments and may include the use of several legacy buses. HT is intended to support connections to a variety of I/O buses, and the specification gives special attention to the PC legacy buses to ensure compatible support.

Several areas must be considered to ensure compatibility with I/O buses, including:

• Protocol differences

• Ordering requirements

• Command translation

• Address space and range differences

• Potential deadlocks

The buses currently supported and discussed by the HT specification include PCI, PCI-X, AGP, and host processor buses, with special attention given to issues associated with PC legacy support via the ISA/LPC buses.