Intel
®
81341 and 81342—Messaging Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
412
Order Number: 315037-002US
There is one base address for all four queues. It is stored in the Queue Base Address
Register (QBAR). The starting addresses of each queue is based on the Queue Base
Address and the Queue Size field.
shows an example of how the circular
queues should be set up based on the Intelligent I/O (I
2
O) Architecture Specification.
Other ordering of the circular queues is possible.
Table 261. Queue Starting Addresses
Queue
Starting Address
Inbound Free Queue
QBAR
Inbound Post Queue
QBAR + Queue Size
Outbound Post Queue
QBAR + 2 * Queue Size
Outbound Free Queue
QBAR + 3 * Queue Size