Peripheral
Devices
The optional
parameter
tt<char
>P"
is
the
decimal
equivalent
of
an
ASCII
character
which
can
be used to
turn
off Record mode.
It
should be
the
first
character
in
a record;
the
default
character
is
tto".
If
tt<char>p" is
omitted
or
if
tto
p
" is specified, no
character
will
turn
off
Record mode.
Termination
can
only occur by pressing
RECORD
MODE
or
initiating
a soft or
hard
reset.
The
reset
can
be
initiated
either
from
the
keyboard
or
from
the
program.
The
termination
character
selected
in
the
escape code is valid only for
the
current
activation
ofRecord mode.
When
Record mode is ended,
the
termination
character
returns
to
the
default
character
C
t
0").
If
the
escape sequence is received from
the
computer,
the
terminal
returns
an
tts"
or
ttF"
character
to
the
program
to indicate ttsuccessful" or ttfailed",
status
execution of
the
escape
sequence.
This
status
check is discussed
later
in
this
section.
When
the
status
character
is
sent
depends on
whether
or
not
the
DCI/DC2
handshake
is
enabled. (Refer to Sections 3
and
9 for information on
handshake
types.)
If
the
DCI/DC2
handshake
is
disabled,
the
character
(always
an
tts") is
sent
immediately
after
the
terminal
receives
the
escape sequence; otherwise,
it
(an tts"
or
ttF")
is
sent
after
Record mode
is
turned
off
and
a
DCI
is
received from
the
computer.
A 256-character buffer is used to hold each record
prior
to
sending
it
to
the
ttto"
device(s).
If
the
record exceeds 256
characters,
the
terminals
handshake
holds off
any
further
transmis-
sionfrom
the
computer
until
the
buffer contents
are
sent
to
the
ttto"
device(s). Records
shorter
than
256
characters
are
indicated by
an
LF
(line feed) character.
In
this
case also,
the
termi-
nals
handshake
holds off
further
transmission
from
the
computer
until
the
buffer
is
cleared.
If
Record mode is
turned
off
with
a partially-filled buffer,
the
contents
are
sent
to
the
ttto"
device(s).
If
the
first
character
in
the
buffer is
the
termination
character, Record mode
is
terminated
and
the
termination
character
is
not
sent
to
the
ttto"
device(s).
DATA
LOGGING MODES
The
terminal
includes a
mechanism
called ttdata logging" whereby
data
can
be
automatically
routed to
the
integral
printer
and/or
an
external
printer.
There
are
two
types
of
data
logging:
top
and
bottom.
Log
Top
Mode
When
the
display is filled
and
another
line of
data
is
entered
through
the
keyboard
or
received
over
a
datacomm
line,
the
top line
in
the
display is
purged
to
make
room for
the
new
line.
With
top logging, each line
that
is purged from
the
top of
the
display
is
printed.
Thus,
while
the
line is ttlost" from display memory,
it
is
maintained
in
hard
copy form.
Figure
6-5
illustrates
top logging.
6-9
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