SMC Networks SMC91C95 - Manual (Page 41)

41
LOOP - Local Loopback. When set, transmit
frames are internally looped to the receiver after
the encoder/decoder. Collision and Carrier Sense
are ignored. No data is sent out. Defaults low to
normal mode. TXENA - Transmit enabled when set. Transmit is
disabled if clear. When the bit is cleared, the
SMC91C95 will complete the current transmission
before stopping. When stopping due to an error,
this bit is automatically cleared.
AUI FDSE FDUPLX EPH_LOOP LOOP LOOPS AT
TRANSMITS
TO
NETWORK
X X X 1 X EPH Block No
X X 1 0 1 ENDEC No
1 0 1 0 0 Cable Yes
0 0 1 0 0 10BASE-T Driver Yes
X 0 0 0 0 Normal CSMA/CD - No
Loopback Yes
X 1 1 0 0 Full Duplex Switched
Ethernet - No loopback
and no SQET Yes