82596CA Datasheet, PDF (42/76 Pages) Intel Corporation – HIGH-PERFORMANCE 32-BIT LOCAL AREA NETWORK COPROCESSOR

82596CA
where
EL B C I S
OK (Bit 13)
A (Bit 12)
Bits 19–28
CMD (Bits 16–18)
Status Bit 11
Status Bit 10
Status Bit 9
Status Bit 8
Status Bit 7
Status Bit 6
Status Bit 5
Status Bit 4
MAX-COL
(Bits 3–0)
LINK OFFSET
TBD POINTER
DEST ADDRESS
LENGTH FIELD
TCB COUNT
EOF Bit
As per standard Command Block (see the NOP command for details)
Error free completion
Indicates that the command was abnormally terminated due to CU Abort control
command If 1 then the command was aborted and if necessary it should be
repeated If this bit is 0 the command was not aborted
Reserved (0 in the 32-bit Segmented and Linear modes)
The transmit command 4h
Late collision A late collision (a collision after the slot time is elapsed) is detected
No Carrier Sense signal during transmission Carrier Sense signal is monitored
from the end of Preamble transmission until the end of the Frame Check Sequence
for TONOCRS^e1 (Transmit On No Carrier Sense mode) it indicates that transmis-
sion has been executed despite a lack of CRS For TONOCRS^e0 (Ethernet
mode) this bit also indicates unsuccessful transmission (transmission stopped
when lack of Carrier Sense has been detected)
Transmission unsuccessful (stopped) due to Loss of CTS
Transmission unsuccessful (stopped) due to DMA Underrun i e the system did
not supply data for transmission
Transmission Deferred i e transmission was not immediate due to previous link
activity
Heartbeat Indicator Indicates that after a previously performed transmission and
before the most recently performed transmission (Interframe Spacing) the CDT
signal was monitored as active This indicates that the Ethernet Transceiver Colli-
sion Detect logic is performing properly The Heartbeat is monitored during the
Interframe Spacing period
Transmission attempt was stopped because the number of collisions exceeded the
maximum allowable number of retries
0 (Reserved)
The number of Collisions experienced during this frame Max Col ^e 0 plus S5 ^e 1
indicates 16 collisions
As per standard Command Block (see the NOP Command for details)
In the 82586 and 32-bit Segmented modes this is the offset of the first Tx Buffer
Descriptor containing the data to be transmitted In the Linear mode this is the 32-
bit address of the first Tx Buffer Descriptor on the list If the TBD POINTER is all 1s
it indicates that no TBD is used
Contains the Destination Address of the frame The least significant bit (MC) indi-
cates the address type
MC ^e 0 Individual Address
MC ^e 1 Multicast or Broadcast Address
If the Destination Address bits are all 1s this is a Broadcast Address
The contents of this 2-byte field are user defined In 802 3 it contains the length of
the data field It is placed in memory in the same order it is transmitted i e most
significant byte first least significant byte second
This 14-bit counter indicates the number of bytes that will be transmitted from the
Transmit Command Block starting from the third byte after the TCB COUNT field
(address n ^a12 in the 32-bit Segmented mode N ^a16 in the Linear mode) The
TCB COUNT field can be any number of bytes (including an odd byte) this allows
the user to transmit a frame with a header having an odd number of bytes The
TCB COUNT field is not used in the 82586 mode
Indicates that the whole frame is kept in the Transmit Command Block In the
Simplified memory model it must be always asserted
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