VISUAL
TECHNOLOGY
INCORPORATED,
RAILROAD
AVENUE,
DUNDEE
PARK,
ANDOVER,
MA
01810
EVEN position: In
like
manner, the
parity
bit
is
set
so
that
each
transmitted character
has
an
even
number
of
ones.
Received character
parity
is
checked and the received character
is
displayed
or
in the event
of
incorrect
parity
the
parity
error symbol
is
displayed.
SPACE position: Transmitted characters have
the
parity
set
to
a zero(space) in this position.
Received
parity
is
not
checked.
MARK
position: In a similar manner, transmitted characters
have
the
parity
bit
set
to
a
one (mark). Received
parity
is
not
checked.
3.1.2.3 Emulation Mode
Two
switches (2, 3
right
bank) select the emulation mode.
VISUAL
200
(VT
-52+),
ADDS
520+, Hazeltine 1500+, and
ADM
-3A+
are all present in the standard term ina
I.
See
Section
4
for
operation and
functionality
in
each
of
these emulation modes.
3.1.2.4
Video
Mode
One switch
(1
right
bank) selects the video presentation, black characters on a wh
ite
back-
ground,
or
white
characters on a black background.
3.1.2.5 Refresh Rate
One switch (8
left
bank) selects either 50
or
60
Hz. refresh rate. This switch does
not
select
the voltage
input
of
110 or
220
volts! When this switch
is
altered power
must
be
cycled
off
then on before the switch position
is
recognized.
See
Section 7
for
input
voltage change
instructions.
3.1.2.6
Half/Full
Duplex
One
switch (7
left
bank) selects Full
or
Half
duplex
operation.
Full Duplex position: Request-to-Send
is
always true while the terminal
is
on line, and
transmitted data
is
totally
independent
of
received data (the
computer
must echo the
data back in order
for
it
to
appear on the screen).
Half
Duplex position: Transmitted data
is
internally
echoed
to
the received data. Request-
to-Send
is
set true when a key
is
typed on the keyboard, and remains true
until
reset
by
the
RST (reset) key,
the
terminal
is
switched
off
line,
or
by
the
typing
of
the terminating code
(see
paragraph 3.1.2.7). RTS
can
also
be
set remotely
as
described in paragraph 3.1.2.7.
3.1.2.7
Half
Duplex Mode
Two
switches
(5,6
left
bank) determine the code which
will
set
and reset RTS depending
on the emulation mode .
• When the terminal
is
set
to
FDX
and
V200
Rei 0.11
or
V210
Rei 0.03
or
later
firm-
ware
is
installed and the
PCB
is
revision E
or
later, a local hardware echo
is
provided
when
the
HDX
switches
are
set
to
the CR position.
If
local echo
is
not
desired in
FDX,
the
HDX
switches must
be
set
to
the Secondary Channel position (OFF).
•
Visual
200
mode, C R
Typing
any key
sets
RTS.
Typing
CR resets RTS. Receiving a
CR
from
the com-
puter
sets
RTS.
6
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