AM79C983AKCW AMD [Advanced Micro Devices], AM79C983AKCW Datasheet - Page 25

• Manufacturer Part Number: AM79C983AKCW
• Manufacturer: AMD [Advanced Micro Devices]

The presence of a valid destination address is deter-
mined by comparing the destination address of the
packet with the Last Source Address Register and the
Preferred Source Address Register associated with the
expansion bus. Comparison is enabled by setting the
EP bit of the Last Source Address Compare Enable
Register and/or the Preferred Source Address
Compare Enable Register. Setting the EP bit of the
Multicast Address Pass Enable Register inhibits com-
pression when the address is a multicast address.
Note: The bit designation is LSB to the
left and MSB to the right. The fields are
transmitted LSB first.
Figure 3. Detailed Report Packet
ROLL- Frame Size has exceeded
BROAD - Broadcast Address Match
MULT - Multicast Address Match
RES - Reserved. Set to Zero.
BRE - Bit Rate Error
ALIGN - Framing Error
CRC - CRC Error
Front of Original Packet
Preamble and SFD
(min 14 Octets long)
1535 bytes
LSB Frame Size
Stat 2 Field
Stat 1 Field
Device ID
(in Octets)
(4 Octets)
New FCS
Port Number
MSB Frame
Size
(in Octets)
(4 Bits)
P R E L I M I N A R Y
19879B-7
Am79C983A
The PR port has six signals: PCLK, PDAT, PENAO,
PENAI, PDRV, and PTAG. PCLK is a 10-MHz clock sig-
nal. PDAT transmits the packet data and is clocked by
the rising edge of PCLK. PENAO is an active-LOW sig-
nal and indicates when the PR port is active. PENAI
senses when a PR port of another IMR2 device is ac-
tive and is an active-LOW signal. PDRV is used to en-
able an external buffer for PCLK and PDAT. PTAG
indicates when the tag is being transmitted.
The signal format is shown in 4. PDAT first transmits
the compressed or uncompressed packet. Then it
transmits the first status field. This field has the format
of the first statistics field shown in 4. At the end of the
first statistics field, PCLK is stopped until the end of the
packet. Then the second statistics field is transmitted
over PDAT along with a new FCS.
Multiple IMR2 devices can be connected to a single
MAC. If an IMR2 device becomes active while another
device is transmitting statistics, the new packet will not
be transmitted over the PR port.
RAUI Port
The RAUI Port is a configurable AUI port. It has the
same signals that are associated with an AUI port: DO,
DI, and CI. For the RAUI Port, these are named RDO,
RDI, and RCI, respectively. The RAUI port can be con-
figured in either normal or reverse mode. When config-
ured in normal mode (default mode), the functionality is
that of an AUI port on a MAC. When configured in re-
verse mode, the RAUI port provides the functionality of
an AUI port on a MAU, with RCI acting as an output.
This reverse configuration allows the RAUI Port to be
connected directly to a MAC. However, the sense of
RDO and RDI does not change with the configuration.
Therefore, in the reverse configuration RDO should be
connected to DI of the MAC and RDI should be con-
nected to DO on the MAC.
Device Configuration
Register Bit 5
0
1
Table 3. RAUI Port
(RCI is an Output)
RAUI Port Mode
Reverse Mode
Normal Mode
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