Links and Channels

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It may be worthwhile at this moment to re-emphasize the difference between a channel and a link.

 

link

a physical device that can be connected to another link by a wire to give a bi-directional connection between two processors, allowing them to communicate.

channel

a uni-directional means for tasks to communicate; the tasks need not be on different processors.

 

 

Communication with a task on another processor through a channel implies the use of links; they are employed to support the channel connection. Communication with a task on the same processor through an internal channel does not make use of links, but instead uses a memory copy operation, either controlled by the CPU or a DMA channel as appropriate.

 

As we have seen, a WIRE statement describes a link which joins two processors, whereas a CONNECT statement describes a channel connecting two tasks.