113
STP2002QFP
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
Sun Microsystems,
Table 144: TX_MAC Configuration Register Definition
Field Bits Description Type
TX_MAC_Enabl
e
0 When set to 1, the TX_MAC will start requesting
packet data from the ETX, and the transmit
Ethernet protocol execution will begin. When
cleared to 0, it will force the TX_MAC state
machines to either remain in the idle state, or to
transition to the idle state and stay there at the
completion of an ongoing packet transmission.
R/W
4:1 Reserved R
Slow_Down 5 When set to 1, this bit will cause the TX_MAC to
check for carrier sense before every transmission
on the medium, and for the entire duration of the
IPG. For normal operation this bit should be
cleared to 0.
R/W
Ignore_Collision 6 When set to 1, this bit will cause the TX_MAC to
ignore collisions on the medium. For normal
operation this bit should be cleared to 0.
R/W
No_FCS 7 When set to 1, this bit will cause the TX_MAC
not to generate the CRC for transmitted frame.
For normal operation this bit should be cleared to
0.
R/W
No_Backoff 8 When this bit is set to ‘1’, the backoff algorithm
in the Protocol Engine is disabled. The TX_MAC
will not back off after a transmission attempt that
collided on the medium. Effectively the random
number chosen by the backoff algorithm is fixed
to ‘0’. For normal operation this bit should be
cleared to ‘0’
R/W
Full_Duplex 9 When this bit is set to 1, the CSMA/CD protocol
is modified such that the TX_MAC will never
give up on a frame transmission.In effect, no limit
will exist on transmission attempts. If the backoff
algorithm reaches the attempts_limit, it will clear
the attempts_counter and continue trying to
transmit the frame until it is successfully trans-
mitted on the medium. For normal operation it is
recommended that this bit is set to 1.
R/W
Never_Give_Up 10 When this bit is set to 1, the CSMA/CD protocol
is modified such that the TX_MAC will never
give up on a frame transmission. In effect, no
limit will exist on transmission attempts. If the
backoff algorithm reaches the attempts_limit, it
will clear the attempts_counter and continue try-
ing to transmit the frame until it is successfully
transmitted on the medium. For normal operation
it is recommended that this bit is set to 1.
R/W