Specifications
SECTION
III
3.1.1 Communications Mode
Proper
display
of
data
on the
terminal
screen depends
in
part
on the
communications
setup
of the
host computer.
In
particular,
host computers
may or may not
send back
("echo")
for
display
on the
terminal's
screen data entered
via the
keyboard
and
transmitted
to
the
host.
If the
host does
not
echo, then
the
terminal
must transmit both
to the
host
and
to
the
screen.
Proper
display
then depends
on
choosing
the
right
"communication
mode"
for the
terminal.
If
the
host
is set to
echo data,
In
Set-Up,
set the
duplex
to FDX
(full
duplex),
or
Enter
the
sequence
ESC D F
If
the
host
is set to not
echo data,
In
Set-Up,
set the
duplex
to HDX
(half
duplex),
or
Enter
the
sequence
ESC D H
NOTE:
if the
host
is set to
echo
and
duplex
is set to
HDX,
all
characters
will
display
double.
If
the
host
is set to not
echo
and
duplex
is set to
FDX,
no
characters
will
be
displayed.
Editing
and the
Communications Mode
Most
of the
time (e.g.,
using
a
word
processing
program),
editing
will
be
done
while
in
Full
Duplex (FDX
on
Line
1)
Conversation (CONV
on
Line
1)
and
Duplex Edit (DUPE
on
Line
3)
mode.
In
this situation,
the
editing
and
cursor-moving keys
are
transmitted
to the
host
and
echoed back
to the
screen.
[NOTE:
if an
application
program cannot interpret
the
code
transmitted
by the
key,
the
command
will
usually
be
ignored.
NOTE
also:
You can
program
a key so
that
it
transmits
a
code
the
application
can
interpret.
See
"Programming"]
In
some configurations,
it may be
appropriate
to use an
alternative
to
Duplex
Editing,
Local
Editing.
In
Local
Editing,
editing
is
on-screen,
the
terminal does
not
transmit codes
for the
following
keys
to the
host:
Arrow
Keys
(Up, Down,
Left,
Right)
BACKSPACE
ERASE
LINE
BACKTAB
ERASE
PAGE
CLEAR
INSERT
CHARACTER
DELETE
CHARACTER
INSERT LINE
DELETE
LINE HOME
ENTER
CE
PAGE
PRINT
SEND
TAB
NOTE: communication between terminal
and
host
may
break down
if you
switch from
Duplex
Editing
to
Local
Editing
and
back
to
Duplex
Editing.
For
example,
if you
move
the
cursor
while
in
Local Editing,
and
then return
to
Duplex
Editing,
the
host thinks
the
cursor
is
in one
position, when
it is
actually
in
another.
3-2