PCI Express Layering Overview

As shown in the figure, PCI Express has three discrete logical layers:

• Transaction Layer
• Data Link Layer
• Physical Layer

Each of these layers is divided into two sections: Transmit and Receive block

PCI Express Layering Diagram Model

PCI-Express

PCI Express X1 Link Model
The major difference between PCI Express and PCI, PCI-Express is a Serial Point to Point interface, whereas PCI is a Parallel. A PCI-Express device is always the driver for its transmitter pairs(s) and is always the target for its receiver pair(s).The Connection between two PCI Express devices is referred to as Link. A links consist of number of Lanes. A lane is a combination of Transmit and Receive pairs. For the first generation of

PCI Express technology, there is only one signaling rate defined, which provides an effective 2.5 Gigabits/second/Lane/direction of raw bandwidth. The data rate is expected to increase with technology advances in the future.

PCI Express configuration has serial links: X1, X2, X4, X8, X12, X16 and X32. An X1 configuration has a single serial path of Transmit and Receive. Likewise X2 configurations have two serial paths of Transmit and Receive. The serial links pronounced as or read as ” by one “- X1 and “by two”-X2 and so on.

Model of X2 serial links

INTRODUCTION

When look back to history we can find so many advancement in technology day today life. When refer to the technology, can find lot of development between every stage. In communication and computer sector the growth is drastic change, people can communicate any where in the world in few seconds because of technical advancement. There are certain times in the evolution of Technology for every generation. Because of technology revolution a new input/output architecture, PCI Express allows computer to process far beyond the limit when compared with the existing technology. The term PCI - Peripheral Component Interconnect.PCI Express is the third generation I/O interconnects.PCI Express communicate the devices simultaneously by implementing dual unidirectional paths, this makes the protocol high speed and low voltage.

The three main technologies,

· PCI

· PCI- X (Derivative of PCI)

· PCI- Express

PCI-X is not the abbreviation of PCI Express. PCI-X evolved from PCI.