Selectively providing data pre-emphasis based upon data content history.

摘要

The present invention comprises a method and apparatus for selectively providing pre-emphasis to the output of a first driver during an initial portion of certain data transitions while transmitting data along a data bus from a source to a destination. The certain data transitions are determined as a function of the content of the history of prior transmitted data cells. In the preferred embodiment, a pre-emphasis driver is connected in parallel to a normal driver and the pre-emphasis driver is activated preferably during the initial portion 32' of a data transition 32 to provide pre-emphasis in response to a control signal being applied to the pre-emphasis driver. The preferred embodiment of the present invention also comprises a sequence detector and control for monitoring the data cells or bits that are inputted to the normal driver to provide a history of the voltage levels of the data bits that are input to the normal driver. Based upon the history, the pre-emphasis driver is selectively operated to increase the slew or magnitude of the slope of a data transition at least during the initial portion 32' of the transition, e.g. transition P2.