Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Table 31. Mailbox Empty/Full Status Register
Bit
Description
31:16 Incoming Mailbox Status. This field indicates which incoming mailbox registers have been written by the Add-On
interface but have not yet been read by the PCI bus. 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, and a value
of zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 31 = Incoming mailbox 4 byte 3
Bit 30 = Incoming mailbox 4 byte 2
Bit 29 = Incoming mailbox 4 byte 1
Bit 28 = Incoming mailbox 4 byte 0
Bit 27 = Incoming mailbox 3 byte 3
Bit 26 = Incoming mailbox 3 byte 2
Bit 25 = Incoming mailbox 3 byte 1
Bit 24 = Incoming mailbox 3 byte 0
Bit 23 = Incoming mailbox 2 byte 3
Bit 22 = Incoming mailbox 2 byte 2
Bit 21 = Incoming mailbox 2 byte 1
Bit 20 = Incoming mailbox 2 byte 0
Bit 19 = Incoming mailbox 1 byte 3
Bit 18 = Incoming mailbox 1 byte 2
Bit 17 = Incoming mailbox 1 byte 1
Bit 16 = Incoming mailbox 1 byte 0
15:00 Outgoing Mailbox Status. This field indicates which out going mail box registers have been written by the PCI bus
interface but have not yet been read by the Add-On 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, and a value
of zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 15 = Outgoing mailbox 4 byte 3
Bit 14 = Outgoing mailbox 4 byte 2
Bit 13 = Outgoing mailbox 4 byte 1
Bit 12 = Outgoing mailbox 4 byte 0
Bit 11 = Outgoing mailbox 3 byte 3
Bit 10 = Outgoing mailbox 3 byte 2
Bit 09 = Outgoing mailbox 3 byte 1
Bit 08 = Outgoing mailbox 3 byte 0
Bit 07 = Outgoing mailbox 2 byte 3
Bit 06 = Outgoing mailbox 2 byte 2
Bit 05 = Outgoing mailbox 2 byte 1
Bit 04 = Outgoing Mailbox 2 byte 0
Bit 03 = Outgoing Mailbox 1 byte 3
Bit 02 = Outgoing Mailbox 1 byte 2
Bit 01 = Outgoing Mailbox 1 byte 1
Bit 00 = Outgoing Mailbox 1 byte 0
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