Motorola MC68302 User Manual page 211

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buffer has been transmitted. Bit 15 is set by the user and cleared by the V.110
controller.
R- Ready
1::::: The data buffer has been prepared for transmission by the user (but
not yet transmitted). No fields of this BD may be written by the user
once this bit is set.
0::::: This buffer is not currently ready for transmission. The user is free
to manipulate this BD and its associated buffer. The V.110 controller
clears this bit after the buffer has been fully transmitted (or after an
error condition is encountered).
X - External Buffer
1 ::::: The buffer associated with this BD is in external memory.
0::::: The buffer associated with this BD is in internal dual-port RAM.
W - Wrap (Final BD in Table)
1 =This is the last BD in the Tx BD table. After this buffer has been used,
the V. 11 O controller will transmit data from the first BD in the table.
0::::: This is not the last BD in the Tx BD table.
NOTE
The user is required to set the wrap bit in one of the first eight BDs;
otherwise, errant behavior may occur.
I - Interrupt
1 =The M68000 core processor will be interrupted when this buffer has
been serviced by the V. 110 controller.
0= No interrupt is generated after this buffer has been serviced.
L- Last
1 =This bit is set by the processor to indicate that this buffer is the last
buffer in the current frame. The V. 110 controller will transmit ones
until the next BD is ready.
O=This buffer is not the last in the message.
Bit 10 - Must be set to zero by the user.
Bits 9-2, 0 - Reserved for future use.
The following bits are written by the V.110 controller after it has finished
transmitting the associated data buffer.
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