NEXT (Inter-core Interrupter (Doorbell/Mailbox))
- Cycles slaved on one side are mastered on the other.
- Need not be symmetric, or have flat address space.
- Busses can be dissimilar.
- Writes can be 'posted' (using internal FIFO).
- (The `busses' on each side use multiplexors and not tri-states.)
- System bandwidth ranges from 1.0 to 2.0 bus bandwidth: inverse proportion to bridge crossing cycles.