~ National ~ Semiconductor - Al Kossow's Bitsavers

7.0 CPU Registers (Continued)
BIT DEFINITION TABLE (Continued)
TRANSCEIVER (Continued)
Table includes control and status bits only. It does not include definitions of bit fields provided for the formatting (de-formatting)
data frames. For further information see the Transceiver Section. (Continued)
Bit Name Location Reset State Function
Receiver SLR Select Line TCR [5] a Selects the receiver input source.
Control
Receiver
SLR Source
(Continued)
a TTL-IN
1 On-Chip Analog
Line Receiver
Transmitter TA Transmitter Active TSR [6] a Reflects the state of TX-ACT, indicating that data is being
Status
transmitted. Is not disabled by [LOOP].
TFE Transmit FIFO NCF [7] 1 Set high when the FIFO is empty. Cleared by writing to
Empty
(RTR).
TFF Transmit FIFO TSR [7] a Set high when the FIFO is full. {RTRl must not be written
Full
when [TFF] is high.
Receiver ACK Poll I NCF [1] a Set high when a 3270 poll lack command is decoded and
Status ACKnowledge [DAV] is asserted. Cleared by reading {RTRl. Undefined in
5250 and 8-bit modes and in the first frame of 3299 modes.
DAV Data Available TSR [3] a Set high when valid data is available in (RTR land (TSR).
Cleared by reading {RTR l , or when an error is detected.
DEME Data Error or NCF [3] a In 3270 or 3299 modes asserted when a byte parity error is
Message End
detected. In 5250 asserted when the [111] station address is
decoded and [DAV] is asserted. Undefined in 8-bit modes
and first frame of 3299 modes.
LA Line Active NCF [5] a Indicates activity on the receiver input. Set high on any
transition; cleared after no input transitions for 16 TCLK
periods.
LTA Line Turn Around NCF [4] a Set high when end of message is detected. Cleared by writing
to {RTR l. writing a "1" to [L T A] or by asserting [TRES].
POLL POLL NCF [0] a Set high when a 3270 poll command is decoded and [DAV] is
asserted. Cleared by reading {RTR l. Undefined in 5250 and
8-bit modes and in the first frame of 3299 modes.
RA Receiver Active TSR [4] a Set high when a valid start sequence is received. Cleared
when either an end of message or an error is detected.
RAR Received NCF [2] a Set high when a 3270 Auto-Response message is decoded
Auto-Response
and [DAV] is asserted. Cleared by reading {RTRl. Undefined
in 5250 and 8-bit modes and in the first frame of 3299 modes.
RE Receiver TSR [5] a Set high when an error is detected. Cleared by reading {ECR l
or by asserting [TRES].
RFF Receive FIFO NCF [6] a Set high when the receive FIFO contains 3 received words.
Full Cleared by reading {RTR l.
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