i960 Messaging Unit
Message registers
- i960 sends and receives messages via special registers
- when written an interrupt generated to i960 or PCI
Doorbell registers
- inbound and outbound doorbells
- either hardware or software can generate doorbell interrupts
- contain interrupt status from other message unit mechanisms
Circular queues
- two inbound and two outbound queues
- posted messages contain orders
- free messages indicate operation completed and message can be reused