DMA controller with channel tagging

Year	Description
1996	Invention patented by Kab Ju Moon and Amjad Z. Qureshi on October 17th, 1996. Abstract: A DMA controller receives a DMA request from a DMA channel and generates a transaction request ID identifying the requested transaction as well as a codec ID identifying the DMA channel. The codec ID is stored in the DMA controller in association with the transaction request ID. The DMA controller obtains control of the bus and outputs a transaction request onto the bus along with the transaction request ID. The DMA controller then relinquishes control of the bus. A device on the bus returns the transaction request ID when it responds (the transaction request ID is "tagged" to the response). The DMA controller uses the returned transaction request ID to look up the codec ID stored in the DMA controller in association with that transaction request ID. The DMA controller uses the codec ID to associate the response with the correct DMA channel. In the event the split transaction is a posted read, the DMA controller uses the returned transaction request ID to supply the data to the DMA channel that issued the DMA request.
Source: selected by the editor from original sources.

Invention: DMA controller with channel tagging