User`s manual
Table 3-10
Line Protocol Parameters Secondary Register Bit Assignments
Bit(s)
Designation
Function
Read/Write
00
Idle Mark When set
to
one, causes the associated data line to
go
Read or Write
to the MARK state at the conclusion
of
transmission
of
the character currently being loaded into the
transmitter
if
both
principal and alternate byte
counts are zero.
When
cleared, sync characters
will
be idled on a :synchronous data line or a MARK
STATE will be asserted on an asynchronous line.
01
Strip Leading Syncs
When set
to
one, causes sync characters arriving on
Read or Write
the associated data line after the achievement
of
synchronization,
but
before the first non-sync
character,
to
be stripped from the incoming data
stream (i.e.,
not
stored in the
RC
Silo). The sync
character(s) with which the receiver achieves
sync are stripped
in
any case.
02
Unused
03-04
Block Check Type Set by the PDP-II program
to
specify the type
of
Read or Write
block check calculation
to
be done for transmissions
and receptions on this line:
03
04
BCType
0 0 LRC-8 (XOR)
I 0
CRC-16(X
I6
+X
IS
+X2
+1)
0
I Unused-I 6
I I
CRC-CCITT (XI 6 + Xl 2 + X
S
+
I)
05
ODCMP
Receive
When set to one, inhibits the Microprocessor from Read or Write
fetching control bytes during character reception on
the associated line
if
reception mode
is
O.
Useful for
increasing throughput and reducing core storage
requirements when using
OOCMP
protocol.
06
OOCMP
Transmit
When
set
to
one, inhibits the Microprocessor from Read or Write
fetching control bytes during character transmission
on the associated line
if
transmission mode
is
O.
Useful for increasing throughput and reducing core
storage requirements when using
OOCMP
protocol.
07
Unused
08-15
OLE Character Contains the Data Link Escape (OLE) character for
Read or Write
the associated line. When a character
is
to be trans-
mitted and the control byte for that character (as
fetched by the
OVII)
has bit
01
set
to
one, the OLE
character
is
fetched from this register by the Micro-
processor and transmitted just prior
to
the character
being processed.
3-34