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How do I do an IEEE-488 pass control from VEE?

It is possible to pass control using VEE for Windows (with some restrictions).

All you have to do is use the interface operations dialog to address the inactive controller to talk, and then send the TCT (take control) IB command byte to it; for example, if the inactive controller is at IB address 5, then you can use this to pass control to it:

+-------+

| Start |

+---+---+

|

+---+-----------------+-----------------+---+

| = | Interface Op's: hpib7@7 | x |

+---+-----------------------------------+---+

| |[SEND UNL ]| |

| |[SEND UNT ]| |

| |[SEND TALK 5 ]| |

| |[SEND CMD 9 ]| | <-- TCT

byte

+---+-----------------------------------+---+

The active controller can then pass control back to VEE, or VEE can execute an ABORT to assert the IB IFC (interface clear) line to regain control:

+-------+

| Start |

+---+---+

|

+---+-----------------+-----------------+---+

| = | Interface Op's: hpib7@7 | x |

+---+-----------------------------------+---+

| |[EXECUTE ABORT ]| |

| | | |

| | | |

| | | |

+---+-----------------------------------+---+

Note this discussion assumes that VEE is running on a system controller.

Note that these notes only apply to VEEWIN using the 82341 card; they do not apply to VEEWIN using the 82335 card, as it cannot assert IFC.

Revision 1.0 December 23 1999 AJF