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The LINK Statement

The LINK statement has the form

       LINK source-id-number:source-device-number,destination-id-number: destination-device-number;...

and causes output PRINTed by the source task to be INPUTted by the destination task using the device numbers provided. The id-numbers do not have to be those of tasks already in progress, since it may be desired to set up a device before a task is in existence to attempt to use it.

The tasks do not, in general, have to be at nodes declared adjacent by a TOPOLOGY statement; the existence of CONTROLLED variables in FALCON pre-supposes a sophisticated means of transferring data between processors which allows any processor to communicate with any other, at some cost in efficiency. Where such mechanisms are not available, use of CONTROLLED variables or the LINK statement may cause tasks to be shifted to accessible nodes.

Note that the NOWAIT and CHARACTER options for input may be useful for such communications.

Also note that this is the only circumstance under which input/output device numbers are local in a FALCON program.

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