Specifications

System Registers 7-33
Figure 7-1 Mailbox Data Structure
Table 7-15 gives the description of the mailbox data structure fields.
Table 7-15 Mailbox Data Structure Description
63 48 47 40 39 32 31 012
MBZ MBZ CMD
BXB-0174 C-94
RBADR <63:0>
WDATA <63:0>
UNPREDICTABLE
RDATA <63:0>
STATUS
E
R
R
D
O
N
UNPREDICTABLE
UNPREDICTABLE
MASK
QW 0
QW 1
QW 2
QW 3
QW 4
QW 5
QW 6
QW 7
56 55
HOSE
BW
2930
QW Bit(s) Name Description
0
<29:0> CMD Remote Bus Command. Controls the remote bus operation
and can include fields such as address only, address width, and
data width. See Alpha SRM.
<30> B Remote Bridge Access. If set, the command is a special or
diagnostic command directed to the remote side. See Alpha
SRM.
<31> W Write Access. If set, the remote bus operation is a write.
<39:32> MASK Disable Byte Mask. Disables bytes within the remote bus ad-
dress. Mask bit <i> set causes the corresponding byte to be dis-
abled. For example, data byte 1 will NOT be written to the re-
mote address if MASK bit <33> is set. See Alpha SRM.
<55:48> HOSE Hose. Specifies the remote bus to be accessed. Bridges can
connect to up to 256 remote buses.
1
<63:0> RBADR Remote Bus Address. Contains the target address of the de-
vice on the remote bus. See Alpha SRM.
2
<63:0> WDATA Write Data. For write commands, contains the data to be
written. For read commands, the field is not used by the
bridge.