MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 262

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

Communications Processor (CP)
4.7.4.2 SMC1 Transmit Buffer Descriptor
The CP reports information about this transmit byte through the BD.
R—Ready
In GCI mode, when the IMP implements the monitor channel protocol, it will clear this bit af-
ter receiving an acknowledgment on the A bit. When the SMC1 data should be transmitted
and this bit is cleared, the channel will retransmit the previous data until new data is provided
by the M68000 core.
L—Last (EOM)
AR—Abort Request
Bits 12–10—Reserved for future use.
AB—Transmit A Bit Value
EB—Transmit E Bit Value
Data—Data Field
4.7.4.3 SMC2 Receive Buffer Descriptor
In the IDL mode, this BD is identical to the SMC1 receive BD. In the GCI mode, SMC2 is
used to control the C/I channel.
4-142
This bit is valid only in GCI mode when the IMP implements the monitor channel protocol.
When this bit is set, the SMC1 channel will transmit the buffer's data and then the end of
message (EOM) indication on the E bit.
This bit is valid only in GCI mode when the IMP implements the monitor channel protocol.
This bit is set by the IMP when an abort request was received on the A bit. The SMC1
transmitter will transmit EOM on the E bit.
This bit is valid only in GCI mode when the monitor channel is in transparent mode.
This bit is valid only in GCI mode when the monitor channel is in transparent mode.
The data field contains the data to be transmitted by SMC1.
15
15
E
R
0 = This bit is cleared by the CP after transmission. The Tx BD is now available to the
1 = This bit is set by the M68000 core to indicate that the data byte associated with this
14
M68000 core.
BD is ready for transmission.
14
L
13
AR
12
RESERVED
—
MC68302 USER’S MANUAL
10
AB
9
EB
8
6
7
5
C/I
DATA
2
MOTOROLA
0
1
0
0
0