MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 252

• Manufacturer Part Number: MC68000
• Manufacturer: MOTOROLA [Motorola, Inc]

Communications Processor (CP)
R—Ready
X—External Buffer
W—Wrap (Final BD in Table)
I—Interrupt
L—Last in Message
Bits 10—2 are reserved for future use; they should be written with zero.
The following status bits are written by the CP after it has finished transmitting the associat-
ed data buffer.
UN—Underrun
CT—CTS Lost
4-132
The transparent controller encountered a transmitter underrun condition while transmit-
ting the associated data buffer.
CTS in NMSI mode or L1GR in IDL/GCI mode was lost during frame transmission.
0 = This buffer is not currently ready for transmission. The user is free to manipulate
1 = The data buffer has been prepared for transmission by the user (but not yet trans-
0 = The buffer associated with this BD is in internal dual-port RAM.
1 = The buffer associated with this BD is in external memory.
0 = This is not the last BD in the Tx BD table.
1 = This is the last BD in the Tx BD table. After this buffer has been used, the CP will
0 = No interrupt is generated after this buffer has been serviced.
1 = When this buffer is serviced by the CP, the TX or TXE bit in the transparent event
0 = The last byte in the buffer is not the last byte in the transmitted block. Data from the
1 = The last byte in the buffer is the last byte in the transmitted block. After this buffer
this BD (or its associated buffer). The CP clears this bit after the buffer has been
fully transmitted or after an error condition has been encountered.
mitted). No fields of this BD may be written by the user once this bit is set.
transmit data from the first BD in the table.
register will be set, which can cause an interrupt.
next transmit buffer (if ready) will be transmitted immediately following the last byte
of this buffer.
is transmitted, the transmitter will require synchronization before the next buffer
can be transmitted.
The user is required to set the wrap bit in one of the first eight
BDs; otherwise, errant behavior may occur.
MC68302 USER’S MANUAL
NOTE
MOTOROLA