Importance

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Abstract

An interface circuit board connected to a VMEbus standard backplane bus of a first data processing system, and also to a Futurebus standard backplane bus of a second data processing system, provides address/data conversion and interrupt service between the two standard bus structures. The Futurebus, being a higher level bus than the VMEbus, has no provision for hardware interrupts; event related data are conventionally transmitted across the Futurebus like any other data item. The interface board signals VMEbus interrupts to Futurebus devices by way of the Futurebus bus arbitration facility. Interrupts generated on the interface circuit board and interrupts from the VMEbus priority interrupt bus are mapped and converted into message numbers, one of which is asserted on the Futurebus arbitration bus as an arbitration number higher than the arbitration numbers assigned to Futurebus devices. Upon winning the arbitration for the Futurebus, the interface board, instead of acquiring it, releases the bus after the devices on the bus have registered the message, which thereby becomes an interrupt across the bus.

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First Claim