Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Table 35. Add-On Mailbox Empty/Full Status Register
Bit
Description
31:16 Outgoing Mailbox Status. This field indicates which outgoing mailbox registers have been written by the Add-On bus
interface but have not yet been read by the PCI bus. Each bit location corresponds to a specific byte within one of
the four outgoing mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, a value of
zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 31 = Outgoing mailbox 4 byte 3
Bit 30 = Outgoing mailbox 4 byte 2
Bit 29 = Outgoing mailbox 4 byte 1
Bit 28 = Outgoing mailbox 4 byte 0
Bit 27 = Outgoing mailbox 3 byte 3
Bit 26 = Outgoing mailbox 3 byte 2
Bit 25 = Outgoing mailbox 3 byte 1
Bit 24 = Outgoing mailbox 3 byte 0
Bit 23 = Outgoing mailbox 2 byte 3
Bit 22 = Outgoing mailbox 2 byte 2
Bit 21 = Outgoing mailbox 2 byte 1
Bit 20 = Outgoing mailbox 2 byte 0
Bit 19 = Outgoing mailbox 1 byte 3
Bit 18 = Outgoing mailbox 1 byte 2
Bit 17 = Outgoing mailbox 1 byte 1
Bit 16 = Outgoing mailbox 1 byte 0
15:00 Incoming Mailbox Status. This field indicates which incoming mailbox registers have been written by the PCI bus but
not yet been read by the Add-On interface. Each bit location corresponds to a specific byte within one of the four
incoming mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, a value of zero signi-
fies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 15 = Incoming mailbox 4 byte 3
Bit 14 = Incoming mailbox 4 byte 2
Bit 13 = Incoming mailbox 4 byte 1
Bit 12 = Incoming mailbox 4 byte 0
Bit 11 = Incoming mailbox 3 byte 3
Bit 10 = Incoming mailbox 3 byte 2
Bit 9 = Incoming mailbox 3 byte 1
Bit 8 = Incoming mailbox 3 byte 0
Bit 7 = Incoming mailbox 2 byte 3
Bit 6 = Incoming mailbox 2 byte 2
Bit 5 = Incoming mailbox 2 byte 1
Bit 4 = Incoming mailbox 2 byte 0
Bit 3 = Incoming mailbox 1 byte 3
Bit 2 = Incoming mailbox 1 byte 2
Bit 1 = Incoming mailbox 1 byte 1
Bit 0 = Incoming mailbox 1 byte 0
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