![](http://datasheet.mmic.net.cn/330000/PM73488-PI_datasheet_16444396/PM73488-PI_95.png)
PMC-Sierra, Inc.
PM73488 QSE
L
PMC-980616
Issue 3
5 Gbit/s ATMSwitch Fabric Element
Released
Datasheet
97
9.3.5
MULTICAST_GROUP_OP
Address: 8
h
Type: Read/Write
Format: Refer to the following table.
9.3.6
UC/MC_FAIRNESS_REGISTER
Address: 9-A
h
Type: Read/Write
Format: Refer to the following table.
9.3.7
EXTENDED_CHIP_MODE
Address: B
h
Type: Read/Write
Field (Bits)
Description
Not used
(7:2)
Write with a 0 to maintain future software compatibility.
INC_BIT
(1)
Increment Bit.
1 Autoincrement MULTICAST_GROUP_INDEX_REGISTER (refer to
section “9.3.3 MULTICAST_GROUP_INDEX_REGISTER” on page 96
)
after each operation.
0 Leave MULTICAST_GROUP_INDEX_REGISTER unchanged.
OPERATION_BIT
(0)
Operation Bit.
1
Enables the write of MULTICAST_GROUP_VECTOR_REGISTER to
the multicast group vector equal to the address referenced by
MULTICAST_GROUP_INDEX_REGISTER.
0
Enables the read of MULTICAST_GROUP_VECTOR_REGISTER from
the multicast group vector equal to the address referenced by
MULTICAST_GROUP_INDEX_REGISTER.
Field (Bits)
Description
UPPER PORTS
(15:8)
Suppose a UC cell and an MC cell of the same priority are contending for the
same output port, where the output port number is between 31 and 16. If
x
bits
are set, then the UC cell has an x/8 probability of winning over the MC cell.
For example, if (any) 4 of the 8 bits are set, then a tie is broken randomly with
a 50-50 chance of either one winning. If none of the bits are set, then MC
always wins, and if all the bits are set then UC always wins.
This register resets to 3A
h
.
LOWER PORTS
(7:0)
Same as above, except this register controls output ports between 15 and 0.
Another difference is that this register resets to A3
h
.