文件名称：PCIE规范详细文档
文件大小：2.18MB
文件格式：PDF
更新时间：2017-10-05 08:19:18
PCIE规范
Traditional multi-drop, parallel bus technology is approaching its practical performance limits. It is clear that balancing system performance requires I/O bandwidth to scale with processing and application demands. There is an industry mandate to re-engineer I/O connectivity within cost constraints. PCI Express comprehends the many I/O requirements presented across the spectrum of computing and communications platforms, and rolls them into a common scalable and extensible I/O industry specification. Alongside these increasing performance demands, the enterprise server and communications markets have the need for improved reliability, security, and quality of service guarantees. This specification will therefore be applicable to multiple market segments. Technology advances in high-speed, point-to-point interconnects enable us to break away from the bandwidth limitations of multi-drop, parallel buses. The PCI Express basic physical layer consists of a differential transmit pair and a differential receive pair. Dual simplex data on these point-to-point connections is self-clocked and its bandwidth increases linearly with interconnect width and frequency. PCI Express takes an additional step of including a message space within its bus protocol that is used to implement legacy “side- band” signals. This further reduction of signal pins produces a very low pin count connection for components and adapters. The PCI Express Transaction, Data Link, and Physical Layers are optimized for chip-to-chip and board-to-board interconnect applications. An inherent limitation of today’s PCI-based platforms is the lack of support for isochronous data delivery, an attribute that is especially important to streaming media applications. To enable these emerging applications, PCI Express adds a virtual channel mechanism. In addition to use for support of isochronous traffic, the virtual channel mechanism provides an infrastructure for future extensions in supporting new applications. By adhering to the PCI Software Model, today’s applications are easily migrated even as emerging applications are enabled.