am79c970 Advanced Micro Devices, am79c970 Datasheet - Page 129

• Manufacturer Part Number: am79c970
• Description: Pcnettm-pci Single-chip Ethernet Controller For Pci Local Bus
• Manufacturer: Advanced Micro Devices

29
28
27
26
1-996
AMD
EXDEF
RTRY
LCOL
LCAR
before the end of the frame was
reached. Upon UFLO error, the
transmitter is turned off (CSR0,
TXON = 0). UFLO is set by the
PCnet-PCI
cleared by the host.
Excessive Deferral. Indicates
that the transmitter has experi-
enced Excessive Deferral on this
transmit frame, where Excessive
Deferral is defined in ISO 8802-3
(IEEE/ANSI 802.3).
LATE COLLISION indicates that
a collision has occurred after the
slot time of the channel has
elapsed. The PCnet-PCI control-
ler does not re-try on late colli-
sions. LCOL is set by the
PCnet-PCI
cleared by the host.
LOSS OF CARRIER is set when
the carrier is lost during an
PCnet-PCI
transmission when in AUI mode.
The PCnet-PCI controller does
not re-try upon loss of carrier. It
will continue to transmit the
whole frame until done. LCAR is
not valid in Internal Loopback
Mode. LCAR is set by the PCnet-
PCI controller and cleared by the
host.
In 10BASE-T mode, LCAR will
be set when T-MAU is in link fail
state.
RETRY ERROR indicates that
the transmitter has failed after 16
attempts to successfully transmit
a message, due to repeated colli-
sions on the medium. If DRTY = 1
in the MODE register, RTRY will
set after 1 failed transmission
attempt. RTRY is set by the
controller-initiated
controller
controller
P R E L I M I N A R Y
and
and
Am79C970
25–16 TDR
15–4
3–0
TMD3
Bit
31–0
Name
RES
TRC
RES
PCnet-PCI
cleared by the host.
MORE, and RTRY are mutually
exclusive.
TIME
CTOMETRY reflects the state of
an internal PCnet-PCI controller
counter that counts at a 10 MHz
rate from the start of a transmis-
sion to the occurrence of a colli-
sion or loss of carrier. This value
is useful in determining the ap-
proximate distance to a cable
fault. The TDR value is written by
the PCnet-PCI controller and is
valid only if RTRY is set.
Note that 10 MHz gives very low
resolution and in general has not
been found to be particularly use-
ful. This feature is here primarily
to maintain full compatibility with
the LANCE device (Am7990).
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 ZERO. In this case
only, the Transmit Retry Count
value of ZERO should be inter-
preted as meaning 16. TRC is
written by the PCnet-PCI control-
ler into the last transmit descrip-
tor of a frame, or when an error
terminates a frame. Valid only
when OWN = 0.
Description
Reserved locations.
DOMAIN
controller
REFLE-
ONE,
and