Tektronix 4023 Instruction Manual page 41

4023
Users
PROGRAMMING
SECTION
II
PART1
INTRODUCTION
Input/Output
Configuration
The 4023
is
both
a transmitting and
a
receiving device.
Standard
interface hardware
provides
full
duplex only.
Full
or
half
duplex
can be achieved
by
use of an Optional
Interface.
Data
can be
transmitted
directly
from
the
keyboard
to
the computer, from
the Terminal
memory
(buffer), or
from
an
optional
auxiliary
unit.
Data
received
by
the Terminal can be
written on
the
display,
can
control
other functions
in
the Terminal, or can control functions
at
auxiliary units.
The LOCAL/ON
LINE
switch
must
be
in
the
ON
LINE
position to
communicate
with the computer.
Data transmitted to the computer
can be echoed back
to
the Terminal's
receiving circuits by
either
the computer,
or
by
selecting
Local
Echo
at
the
Interface Unit
(if
the
Interface Unit
is
equipped with
Local
Echo
capability).
Under
Local
Echo
conditions, data from
the keyboard
or
auxiliary unit
is
simultaneously
sent to the
computer and
the
4023
receiving
circuits.
All
data
from
the computer
enters the Terminal
memory
and
is
displayed.
The 4023
operates independent
of the computer when
the
LOCAL/ON
LINE
switch
is
set to
LOCAL.
Local
operation permits
keyboard
or auxiliary unit data to
be
written on
the display or otherwise
executed
(to a degree)
by
the Terminal.
Summary
of Terminal Configuration
The
following describes the standard
4023
configura-
tion.
Where
Strappable
Options
affect the Terminal
configuration,
special notation
will
be
given
(Strappable
Options information can
be found
in
Part
2
of
this
Section).
or operator
attempts
to give
a
line
feed
past the
bottom
line.
This
is
known
as
"page
full."
In
BUFFER,
the
Terminal
goes busy
when
the computer
or
operator
attempts
to enter a
line
feed past the bottom
line.
With
flagged
interfaces, this
will
stop data flowing to the
4023
without
loss.
With
unflagged systems
(such as RS-232),
further received data
will
be confined
to the bottom
line.
Pressing the
RETURN
key
also performs
a line feed.
A
computer-generated
CR
does not perform
a
simultaneous
line feed.
The
effect of
CR
on
line feed can be changed by
strap placement (CR
DOES
LF
strap)
on
the Keyboard
Interface Card.
The LF
(line feed)
code from
either the
LF
key
or the
program, performs
a line
feed
function
only.
It
can be
strapped to
also
perform
a carriage return.
See the
LF
DOES CR
strap
on
the
Keyboard
Interface Card.
When
ON
LINE
and
entering
buffer data
to the
computer,
carriage
returns are transmitted
at
the end
of
a
line, line feeds
are
not transmitted. Line feeds can
also
be
transmitted by placement
of the
EOL
LF
GEN
Strap
on
the
Control Card.
When
no
data
resides
in a line,
CR
and
LF
transmissions
are suppressed.
The
standard 4023
transmits
an
End
of
Message
character
as
the
last
character
in
an
enter sequence. The
standard
End
of Message
character
is
CR.
However,
the
MESSAGE END
straps
on
the Control
Card can be strapped
to enable any ASCII
control character
to be used
as the
Message End
Character.
The 4023
always performs
(does not
transmit)
a
carriage
return
after
the
last
character transmitted,
whether
the
Message
End
Character
is
CR
or not.
The 4023
displays information
on
24
lines
of 80
characters
each. Display
formatting
capabilities are
standard.
The 4023 communicates
directly with
a
computer,
or
communicates
with the computer
via
the Terminal
buffer.
In
DIRECT,
automatic
roll-up occurs
when
the
computer
Buffered data from
the standard 4023
is
entered by
page,
and not by
line.
Once
an enter
sequence
is
activated,
transmission continues
until
the
entire
message
is
trans-
mitted.
However,
for
those computer
systems
that can
handle only
a line
of data
at a
time, the Terminal can be
configured
to
meet
their
needs by placement
of the
PROMPT
Mode
strap
on
the Control Card. This
strap causes
buffer contents to be transmitted
a line at a
time. After
a
line
is
transmitted, cursor
movement
stops, awaiting the
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