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Motorola MC68838 User Manual page 26

Media access controller
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COPY_ALL—Copy All
This bit copies or passes extra frames and fragments to the FSI. The only frames that
are copied are LLC, SMT, implementor, and reserved frames. COPY_ALL is intended
for use in monitor and analyzer stations.
00 = The MAC attempts to copy all LLC, SMT, reserved for implementor, and
reserved for future standardization frames that have valid length, whose DA is
matched, whose SA is not matched (subject to COPY_OWN) or is an NSA
frame, and is not a secondary NSA frame.
01 = The MAC additionally copies MAC and void frames that: have valid length,
whose DA is matched, and whose SA is not matched (subject to COPY_OWN).
10 = The MAC additionally copies tokens and frames that: are too short (but with an
even number of data symbols), whose DA is not matched, or whose SA is
matched.
11 = The MAC additionally copies fragments, format errors, and frames with an odd
number of data symbols.
When COPY_ALL = 10 or 11, the MAC will still flush (not copy) secondary NSA frames
if COPY_EXTRA_SMT = 00. Only monitor systems should set COPY_ALL to 10 or 11.
COPY_OWN—Copy Frames Sent by This Station
The MAC chip ignores this bit when COPY_ALL = 11 or 10 or if the received frame is an
NSA frame. The COPY_OWN mode of operation is not intended for normal operation
but is reserved for special monitor stations and for ring loopback tests applicable to all
stations.
0 = The MAC does not copy frames that it is currently sending nor frames that it
believes it previously sent, even if the MAC is requested to copy all frames with a
certain FC or DA (see the following register fields).
1 = The MAC copies frames whose SA is matched if the frame would be copied
otherwise and other frames only if the frame is directly addressed to the station.
(DA = broadcast, my long address register, or my short address register.)
COPY_EXTRA_SMT—Copy Certain Extra SMT Frames
When COPY_ALL = 11 or 10, this bit field is ignored (except that secondary NSA frames
are still flushed when COPY_EXTRA_SMT = 00). This bit field does not affect how the
MAC sets the A and C control indicators.
00 = The MAC copies valid SMT frames if the DA is matched and the frame is not a
secondary NSA frame and the SA is not matched or the frame is a primary NSA
frame.
01 = The MAC additionally copies secondary NSA frames whose DA is matched.
10 = The MAC additionally copies all NSA frames or 48-bit group-addressed SMT
frames whose SA is not matched (subject to COPY_OWN).
11 = The MAC additionally copies all NSA frames or 8-bit addressed SMT frames
whose SA is not matched (subject to COPY_OWN).
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MC68838 USER'S MANUAL
MOTOROLA

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