AM79C971VCW Advanced Micro Devices, AM79C971VCW Datasheet - Page 189

• Manufacturer Part Number: AM79C971VCW
• Description: PCnet-FAST Single-Chip Full-Duplex 10/100 Mbps Ethernet Controller for PCI Local Bus
• Manufacturer: Advanced Micro Devices

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27
LCOL
LCAR
mit frame, where Excessive De-
ferral is defined in the ISO 8802-3
(IEEE/ANSI 802.3) standard. Ex-
cessive Deferral will also set the
interrupt bit EXDINT (CSR5, bit
7).
Late Collision indicates that a col-
lision has occurred after the first
channel slot time has elapsed.
The Am79C971 controller does
not retry on late collisions. LCOL
is set by the Am79C971 controller
and cleared by the host.
Loss of Carrier is set when the
carrier
Am79C971
transmission when in AUI mode
and the device is operating in
half-duplex
Am79C971 controller does not
retry upon loss of carrier. It will
continue to transmit the whole
frame until done. LCAR will not
be set when the device is operat-
ing in full-duplex mode and the
AUI port is active. LCAR is not
valid in Internal Loopback Mode.
LCAR is set by the Am79C971
controller and cleared by the
host.
LCAR does not reflect a link sta-
tus problem on the external PHY.
In 10BASE-T mode, LCAR will be
set when the T-MAU was in Link
Fail state during the transmis-
sion.
is
controller
lost
mode.
during
initiated
The
Am79C971
an
26
25-16 RES
15-4
3-0
TMD3
Bit
31-0
RTRY
RES
TRC
Name
US
Retry error indicates that the
transmitter has failed after 16 at-
tempts to successfully transmit a
message, due to repeated colli-
sions on the medium. If DRTY is
set to 1 in the MODE register,
RTRY will set after one failed
transmission attempt. RTRY is
set by the Am79C971 controller
and cleared by the host.
Reserved locations.
Reserved locations.
Transmit Retry Count. Indicates
the number of transmit retries of
the associated packet. The maxi-
mum count is 15. However, if a
RETRY error occurs, the count
will roll over to 0.
In this case only, the Transmit
Retry Count value of 0 should be
interpreted as meaning 16. TRC
is written by the Am79C971 con-
troller into the last transmit de-
scriptor of a frame, or when an
error terminates a frame. Valid
only when OWN is cleared to 0.
User Space. Reserved for user
defined space.
Description
189