AM79C983A datasheet(38/60 Pages) AMD

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Am79C983A

PRELIMINARY

are ignored. This feature is useful when implementing

port switching. The IMR2 device connected to the QuIET

device serial interface will still report correct status on

the Link and Polarity LEDs. The ports default to the

XENA value on reset.

Pn/AUI/RAUI

Isolate the corresponding port

Connect the corresponding port

Note: If a port is isolated during an incoming or transmit-

ted packet, repeating the packet is immediately stopped.

If a port is connected during an incoming packet, the ac-

tual connection is delayed until after the end of the packet.

If a port is connected while the IMR2 device is repeating

a packet, the connection is made immediately.

Extended Distance Enable

Address:

1110 1000

Setting a bit on this register lowers the input threshold

on RXD of the corresponding QuIET transceiver. This

allows the use of a twisted pair cable longer than 100

meters. This register is only in effect if the correspond-

ing port is connected to a QuIET device. On reset, this

TPn/SPn

Extended

Distance

Option

disabled

Extended

Distance

Option

enabled

Automatic Last Source Address Intrusion Control

Address:

1110 1001

Automatic Intrusion Control disables a port automati-

cally when a valid packet (no errors) is received with a

source address which is not a valid address for that

port. Before a bit on this register is set, the correspond-

ing Last Source Address Register should contain a

valid address for that port. On reset, this register de-

faults to Automatic Intrusion Control with Last Source

Address disabled. See note under

Automatic Preferred

Source Address Intrusion Control.

Pn/AUI/RAU

Automatic Intrusion Control with

Last Source Address disabled

Automatic Intrusion Control with

Last Source Address enabled

Automatic Preferred Source Address Intrusion Control

Address:

1110 1010

Automatic Intrusion Control disables a port automatically

when a valid packet (no errors) is received with a source

address which is not a valid address for that port. Before

a bit on this register is set, the corresponding Preferred

Address register should contain a valid address for that

port. On reset, this register defaults to Automatic Intrusion

Control with Preferred Source Address disabled.

Pn/AUI/RAUI

Automatic Intrusion Control with

Preferred

Source

Address

disabled

Automatic Intrusion Control with

Preferred

Source

Address

enabled

Note: The Automatic Preferred Source Address Intru-

sion Control Register and the Automatic Last Source Ad-

dress Intrusion Control Register work together. If intrusion

on a port is not enabled on either register, intrusion control

is not performed for that port. If intrusion on a port is en-

abled on only one of the intrusion control registers, intru-

sion control is based on the corresponding enabled

control registers, the port is disabled if the source address

fails to match both the Last Source Address Register and

the Preferred Source Address Register.

Last Source Address Lock Control

Address:

1110 1011

Whenever the source address of an incoming packet is

different from the Last Source Address Register, the

new source address is written into the Last Source Ad-

dress Register. Setting a bit on this register disables

automatic updating of the Last Source Address Regis-

ter based on the last received packet. The Last Source

Address Register can still be written into via the node

processor interface. On reset, this register defaults to

Last Source Address Lock disabled. Note that a re-

peater that uses Last Source Address Lock Control will

not comply with IETF RFC 1516.

RAUI

AUI P11 P10 P9

D Port Read/Write

Byte 0

Byte 1

MSB

LSB

TP7

TP6 TP5

TP4

TP3

TP2

TP1

TP0

SP3 SP2 SP1 SP0 TP11 TP10 TP9 TP8

Byte 0

Byte 1

D Port Read/Write

MSB

LSB

RAUI

AUI P11 P10 P9

D Port Read/Write

Byte 0

Byte 1

MSB

LSB

RAUI

AUI P11 P10 P9

D Port Read/ Write

Byte 0

Byte 1

MSB

LSB

RAUI

AUI P11 P10 P9

D Port Read/Write

Byte 0

Byte 1

MSB

LSB

AM79C983A Datasheet(PDF) 38 Page - Advanced Micro Devices

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