AM79C940KCW AMD [Advanced Micro Devices], AM79C940KCW Datasheet - Page 56

• Manufacturer Part Number: AM79C940KCW
• Description: Media Access Controller for Ethernet (MACE)
• Manufacturer: AMD [Advanced Micro Devices]

data without addition of an FCS field, and the FCS will be
calculated and verified at the receiver.
The loopback facilities of the MACE device allow full op-
eration to be verified without disturbance to the network.
Loopback operation is also affected by the state of the
Loopback Control bits (LOOP [0–1]) in the User Test
Register. This affects whether the internal MENDEC is
considered part of the internal or external loop-
back path.
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Am79C940
When in the loopback mode(s), the multicast address
detection feature of the MACE device, programmed by
the contents of the Logical Address Filter (LADR [63–0])
can only be tested when RCVFCSE = 1, allocating the
CRC generator to the receiver. All other features
operate identically in loopback as in normal operation,
such as automatic transmit padding and receive
pad stripping.