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KEYBOARD DISPLAY EDITOR
VTED is a very basic editor for use on any keyboard
display terminal. It has only seven special function keys which
are used for editing: Cursor-up, Cursor-down, Cursor-right,
Cursor-left, Rubout, EOL, and EOS.
The philosophy of this editor is simple:
What you see is what you get! In other words, whatever appears
on the display screen is what is in your file. For instance, there
are never any extraneous characters on the screen such as Backslashes
or the echoes of rubbed out characters. When a rubout is hit, the
cursor backs up over t he last character typed and deletes it. If
the cursor is at the beginning of a line and a rubout is typed,
then the <CR> is deleted from the file and the cursor is placed
at the end of the previous line.
The following is a description of the operating proceedures
FILE NAME? (User now types name of file to
be created or edited)
If the file already exists, VTED
will respond with:
FILE ALREADY EXISTS
DO YOU WANT TO: PROOF, APPEND, OR OVERWRITE?
(The user should now answer with a "P",
"A", or "O".)
1) If the file name supplied by the user did not previously
exist, then the screen will go blank signaling that the editor
is ready to accept text. From this point on all text entered
through the keyboard is put into the specified file.
2) If the file specified by the user already exists on the disk,
then the user has three options available:
A) The user may OVERWRITE the existing file. This
causes a new file to be started with the specified name, and
the old file is renamed to a file with the same name but a
unique extension. The screen will then go blank signaling
that the editor is ready to receive text.
B) The user may APPEND te xt to the end of the specified
file. This causes the specified file to be opened and
scanned to it's end. The editor will type out the last
five lines previously entered into the file, and will start
accepting text to be appended to the end of the file.
C) The user may PROOF the specified file. This option
causes the specified file to be renamed to a file with the
same name and a unique extension. Then a new file with the
specified name is opened. This file is empty at the start,
and the internal buffer of the editor contains all of the text
from the original file. The user can proof the original
fi le by using the Cursor Control keys to scan through the
file a line at a time, making edits when necessary. The screen
goes blank at the start when the editor is ready to receive editing commands.
Position the cursor at the end of the previous line. All
text which is passed over is placed in the internal buffer
of the editor. This text can be added to the file again with
the Cursor-right or the Cursor-down commands.
Add text up until the next <CR>
from the internal buffer to the end of the file.
If there is no text in the internal
buffer then this command will do nothing.
Move the cursor left over one word. Put all text passed over
into the internal buffer. If the cursor is at the start of
a line, move the cursor to the end of the previous line.
Move the cursor right one word. A word of text is taken from
the end of the internal buffer and is added to the end of the
Rubout one character to the left. The cursor will be moved
to the left one space and that character will be deleted from
the file. The rubbed-out character will not be placed into
the internal buffer of the editor. If the cursor is at the
start of a line , the <CR> will be deleted form the file
and the cursor will be moved to the end of the previous line.
Erase through the end of the current line, including the
<CR> at the end of this line. This key is used for deleting
a whole line at a time instead of using multiple rubouts.
Erase through the end of the file. This command is used
to delete all text from the current cursor position through
the end of the file. Any text in the internal buffer is
also deleted. Because of the severity of this command,
VTED requires that two EOS characters be typed before
any deleting is performed.
Insert ing text with VTED:
Text is inserted into the file by moving the cursor to the
desired location with the Cursor moving commands, and then
just typing the text to be inserted.
Deleteing text with VTED:
Text is deleted by positioning the Cursor at the end of the
word to be deleted, and then typing a Rubout for each character
to be deleted.
Exiting from VTED:
To Exit from VTED the user types a <CNTRL>C. This will
cause the editor to close out the file, appending any text in
the buffer to the text already entered.
Upper and Lower Case Characters:
VTED always accepts both upper and lower case charac ters. However
on terminals such as the VT-05 where the keyboard is both upper and
lower case and the screen is only upper case, VTED will simulate
upper case characters by placing a "^" in front of all upper case charactrers.
This allows the typist to see if a character was entered as an upper
or lower case character at a glance. If the terminal being used
is capable of displaying both upper and lower case characters, then
the user should turn on lower case mode before starting the editor
(Use the monitor command "SET TTY LC"). Likewise, if the
terminal being used does not have an upper and lower case keyboard
then the user should also give the "SET TTY LC" command
to signal the editor not to put a "^" in front of every upper case
letter. (VT-06's fall into this catagory).
VTED Design Goals
A) VTED was written to be used by the casual computer user.
Since there are only a limited number of commands which are
graphic in nature, VTED is easy to learn and easy to
remember even if the computer is used very infrequently.
B) VTED is best suited for a terminal running at 300 baud
C) With the upper and lower case
capabilities built into the editor, VTED is an excelent
entry program for RUNOFF text.
D) VTED does automatic checkpointing of the file that is being
created. The file is kept on the disk on a line by line basis.
Thus if the system crashes during an editing session, the only
information that is lost should be any partially typed
A) VTED will not let the typist enter a <LF>. If the
<LF> key is struck, VTED rings the terminal's bell
and turns the <LF> into a <CR>. This feature exists
because RUNOFF gets very ill when it sees a <LF>
and no preceeding <CR>.
B) VTED will not allow a FORM FEED (<CNTRL>L)
to be entered unless it is preceeded by a <CR> or another
FOR M FEED. If an attempt is made to enter a FORM FEED
incorrectly, VTED will ring the bell and insert a <CR>
before the FORM FEED.
C) VTED tries to determine the baud rate at which the terminal
is operating. This is done by timing the typeout of a string
of characters. If the system is heavily loaded, this calculation
may not be correct. To insure that the correct number
of fill characters will be used for the higher speed terminals,
the user should set the correct filler class before starting
VTED. This is done with a "SET TTY FILL n"
command, where n is: 0 for 300 baud or less, 1 for 600 baud,
2 for 1200 ba ud, and 3 for 2400 baud.
D) Since VTED is simulating uppercase characters by typing
an uparrow in front of each uppercase character, the editor
must run in "no echo" mode and must do it's own echoing.
This sometimes causes a delay in the echoing of typed characters
on a heavily loaded system. Hopefully the experienced typist
will not notice this lag in echoing.