User`s manual
Mode
1
(Transition
to
Transparent
Reception)
I n
this
mode,
the
system
initializes
for
the
reception
of
transparent
text.
Mode
I is
entered
only
from
Mode
0 following
reception
of
a
OLE.
An
STX
is
expected;
if
one
is
received, it is
discarded
(an
inter-
rupt
is
generated
to
set
the
Transparent
Data
flag).
and
Mode
3 is set.
If
a
positive
acknowledgement
character
(ACK,
WACK,
RVI)
is
received,
an
interrupt
is
generated
to
turn
the
buffer
contents
over
to
the
protocol
module
for
resumption
of
transmission,
and
the
OVII
is
returned
to
Mode
O.
Receipt
of
the
ENQ
repeat
request
causes
an
interrupt
to
set
an
Error
flag
and
turn
buffer
contents
over
to
the
protocol
module.
All
other
received
characters
are
stored,
an
interrupt
is
generated,
and
the
OVII
is
returned
to
Mode
O.
Mode
2
(Non-Transparent
Data
Reception)
The
system
receives
non-transparent
text
(including
header,
if
sent)
in this
mode.
All
characters
are
stored
and
included
in
the
BCC,
except
as follows:
JIB
-
store
the
character,
mdude
in
BCC
and
receive BCC next.
Interrupt.
turn
buffer
con-
tents
over
to
protocol
module.
ETB
or
ETX
-
store
the
character,
include
in
BCC
and
receive
BCC
next.
Set
End-of-Block
flag
and
turn
buffer
over
to
protocol
module.
Go
to
Mode
O.
ENQ
-
discard
the
character
and
set
error
flag.
Interrupt
and
turn
buffer
over
to
protocol
mod-
ule.
Return
to
Mode
O.
S Y N -
discard.
Mode
3
(Transparent
Data
Reception)
Transparent
text
is
received in this
mode.
All
charac-
ters
except
0
LE
are
sorted
and
included
in
the
BCC.
A
OLE,
if
received,
is
discarded,
and
Mode
4
(Trans-
parent
Control
Character
Reception)
is set.
Mode
4
(Transparent
Control
Character
Reception)
Control
characters
received in
the
transparent
data
stream
are
processed
in this
mode.
The
usual
control
characters
would
be
the
block
delimiters,
ITB,
ETB,
or
ETX;
these
are
included
in
the
BCC,
which
is
received
immediately
after
them.
The
ITB
is
stored
and
requires
a
change
to
Mode
5
to
strip
syncs
and
then
to
get
the
rest
of
the
data
block.
ETB
or
ETX
is
stored
and
return
to
Mode
0 is
made.
An
interrupt
is
generated,
the
buffer
contents
are
turned
over
to
the
protocol
module,
and
address
and
byte
counts
are
set
to
receive
the
2-byte
BCC.
Mode
4
responds
to
other
control
characters
as
follows:
DLE
-
store
the
character,
include
in
the
BCC,
return
to
Mode
2.
STX
-
discard,
include
in
BCC,
return
to
Mode
3.
ENQ
-
interrupt,
store
the
character,
set
Error
flag,
return
to
Mode
O.
SYN
-
discard,
return
to
Mode
3.
A II
Other
Characters -
store,
include
in
BCC,
return
to
mode
3.
Mode
5
(Transparent
Intermediate
Data
Reception)
S
YN
-
discard
DLE
-
discard,
include
in
BCC.
go
to
mode
4.
All
Other Characters -
Interrupt,
store,
return
buffer
to
the
protocol
module
with
errors.
Go
to
mode
O.
3.6.5
D
DCM
P Implementation
The
method
suggested
for
OOCMP
implementation
uses a single
control
table
for
both
send
and
receive.
Buffers
are
configured
so
that
the
only
interrupts
required
are
those
resulting
from
zero
byte
counts.
Reference
Figure
B-4
for
DDCMP
data
message
format.
3.6.5.1
Transmission
Control -
Figure
3-7 is a flow
chart
for
the
ODCMP
transmission
process.
Initially,
the
OV
II
principal
transmit
registers
are
set
with
the
base
address
and
byte
count
of
the
data
buffer
con-
taining
the
header,
with bit
15
of
the
byte
count
set
to
zero,
to
cause
BCC
transmission
at
zero
byte
count
time
(reference
Paragraph
3.1.4.2).
I f a
numbered
(data)
message
or
bootstrap
message
is
being
sent,
set
the
alternate
transmit
registers
with
the
base
address
and
byte
count
of
the
first
data
buffer
containing
the
actual
data.
When
setting
up
to
trans-
mit
the
last
data
buffer, set
bit
15
of
the
byte
count
to
zero
to
cause
BCC
transmission
at
zero
byte
count
time.
3-47