AM79C983A datasheet(42/60 Pages) AMD

42 / 60 page

Am79C983A

PRELIMINARY

The contents of all attribute registers are maintained

during hardware or software reset.

These attributes and their deﬁnitions comply with the

IEEE 802.3 Repeater Management standard,

Section19 (

Layer Management for 10 Mb/s Baseband

Repeaters). A brief description of attributes is included

here for reference only. For more details refer to the

IEEE document. An IMR2-based hub can be designed

that will comply with IETF RFC 1515 and RFC 1516.

The Port Attribute Registers can be written into if one of

two conditions are met. The ﬁrst is when either the M bit

or the R bit on the Device Conﬁguration Register is set.

The second is when the corresponding port is disabled.

Readable Frames

Address:

1110 0000

Readable Frames is a read-only attribute that counts

the number of valid frames detected by the port. Valid

frames are from 64 bytes to 1518 bytes in length, have

a valid frame CRC, and are received without a collision.

This attribute is a 32-bit counter with a minimum roll-

over time of 80 hours.

Readable Octets

Address:

1110 0001

Readable Octets is a read-only attribute that counts the

number of octets received on each port. This number is

determined by adding the frame length to this register at

the completion of every valid frame.This attribute is a 32-

bit counter with a minimum rollover time of 58 minutes.

Frame Check Sequence (FCS) Errors

Address:

1110 0010

FrameCheckSequence (FCS) Errors is a read-only

attribute that counts the number of frames detected on

each port with an invalid frame check sequence. This

counter is incremented on each frame of valid length

(64 bytes to 1518 bytes) that does not suffer a collision

during the frame. This counter is incremented on each

invalid frame. However, it is not incremented for frames

with both framing errors and frame check sequence

errors. This attribute is a 32-bit counter with a minimum

rollover time of 80 hours.

Alignment Errors

Address:

1110 0011

Alignment Errors is a read-only attribute that counts the

number of frames detected on each port with an FCS

error and a framing error. This counter is incremented on

each frame of valid length (64 bytes to 1518 bytes) that

does not suffer a collision during the frame. Frames that

have both framing errors and FCS errors are counted by

this attribute, but not by the Frame Check Sequence

Errors attribute. This attribute is a 32-bit counter with a

minimum rollover time of 80 hours.

Frames Too Long

Address:

1110 0100

Frames Too Long is a read-only attribute that counts

the number of frames that exceed the maximum valid

packet length of 1518 bytes. This attribute is a 32-bit

counter with a minimum rollover time of 61 days.

bit 0

bit 31

bit 24

D Port Read

LSB

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

MSB

bit 0

bit 31

bit 24

D Port Read

LSB

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

MSB

bit 0

bit 31

bit 24

D Port Read

LSB

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

MSB

bit 0

bit 31

bit 24

D Port Read

LSB

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

MSB

bit 0

bit 31

bit 24

D Port Read

LSB

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

MSB

AM79C983A Datasheet(PDF) 42 Page - Advanced Micro Devices

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