DP8390 NSC [National Semiconductor], DP8390 Datasheet - Page 24

• Manufacturer Part Number: DP8390
• Description: NIC Network Interface Controller
• Manufacturer: NSC [National Semiconductor]

10 0 Internal Registers
10 3 Register Descriptions (Continued)
TRANSMIT STATUS REGISTER (TSR)
This register records events that occur on the media during transmission of a packet It is cleared when the next transmission is
initiated by the host All bits remain low unless the event that corresponds to a particular bit occurs during transmission Each
transmission should be followed by a read of this register The contents of this register are not specified until after the first
transmission
Bit
D0
D1
D2
D3
D4
D5
D6
D7
reserved
Symbol
OWC
COL
CRS
CDH
PTX
ABT
FU
OWC
7
(Continued)
CDH
PACKET TRANSMITTED Indicates transmission without error (No excessive
collisions or FIFO underrun) (ABT
reserved
TRANSMIT COLLIDED Indicates that the transmission collided at least once
with another station on the network The number of collisions is recorded in the
Number of Collisions Registers (NCR)
TRANSMIT ABORTED Indicates the NIC aborted transmission because of
excessive collisions (Total number of transmissions including original
transmission attempt equals 16)
CARRIER SENSE LOST This bit is set when carrier is lost during transmission
of the packet Carrier Sense is monitored from the end of Preamble Synch until
TXEN is dropped Transmission is not aborted on loss of carrier
FIFO UNDERRUN If the NIC cannot gain access of the bus before the FIFO
empties this bit is set Transmission of the packet will be aborted
CD HEARTBEAT Failure of the transceiver to transmit a collision signal after
transmission of a packet will set this bit The Collision Detect (CD) heartbeat
signal must commence during the first 6 4 s of the Interframe Gap following a
transmission In certain collisions the CD Heartbeat bit will be set even though
the transceiver is not performing the CD heartbeat test
OUT OF WINDOW COLLISION Indicates that a collision occurred after a slot
time (51 2 s) Transmissions rescheduled as in normal collisions
04H (READ)
6
FU
5
CRS
4
24
ABT
3
COL
2
Description
e
‘‘0’’ FU
1
PTX
e
0
‘‘0’’)