HELP TTY                                   Jonathan Laventhol, 4 October 1983

There are various keys on the terminal which perform important
functions. These are dependent on the installation, and so in the
documentation we call them by their function (written in upper case
between angle brackets, e.g. <INTERRUPT>).

Please check with your installation manager to find out which keys have
which function on the machine you use. You can alter this in your login
startup file, if necessary (using the Unix 'stty' command), but for
details you will have to consult UNIX manuals.

CONTENTS - (Use <ENTER> g to access required sections)

 -- Example key mappings
 -- <INTERRUPT>
 -- <QUIT>
 -- <END-OF-FILE>
 -- <SUSPEND>
 -- <ERASE>
 -- <KILL>
 -- <WORD-ERASE>
 -- <START> and <STOP>
 -- <RETURN>
 -- NOTE

-- Example key mappings -----------------------------------------------

The following is a commonly used set of mappings of functions
to keystrokes especially on DEC computers.

     <INTERRUPT>       is <CTRL>-C
     <QUIT>            is <CTRL>-Y
     <END-OF-FILE>     is <CTRL>-Z  (sometimes <CTRL>-D)
     <SUSPEND>         is <CTRL>-\  (sometimes <CTRL>-Z)

     <ERASE>           is DEL          (a key marked del)
     <KILL>            is <CTRL>-U
     <WORD-ERASE>      is <CTRL>-W

     <START>           is <CTRL>-Q
     <STOP>            is <CTRL>-S

     <RETURN>          is the RETURN key or <CTRL>-M

The functions of the various keys is described below.

-- <INTERRUPT> --------------------------------------------------------

This interrupts the computer, usually stopping whatever program is
running, and returns you to some known and hopefully reassuring state.
This is useful if you think the machine is ignoring you, or if you feel
like stopping the program for some reason.  Be careful though, because
usually it isn't possible to get the program running again from where it
left off -- you probably will have to restart it. Inside POPLOG you will
get a message like "Setpop" or "Setlisp" which means that everything is
under control.  Otherwise you should get a helpful prompt back.
In POPLOG you can alter the effect of the <INTERRUPT> key by assigning
a suitable procedure value to the POP-11 variable INTERRUPT.
See HELP *INTERRUPT

-- <QUIT> -------------------------------------------------------------

Sometimes the <INTERRUPT> key doesn't appear to work, and you really
think the machine is ignoring you. Then you can use the <QUIT> key, which
really should stop the program in its tracks. If it doesn't, ask for
help from a human. Sometimes this will leave a file called "core" in
your directory, which you should remove or ignore.

Inside POPLOG, the effect of pressing this key depends on whether you
press it once, or do it twice in quick succession.

Pressing it ONCE has the effect of invoking the procedure "setpop" which
interrupts all running procedures and goes back to the "top level". It
will generally leave you outside the editor, VED. (See HELP * SETPOP)

Pressing it TWICE in very quick succession will make it leave POPLOG
fairly abruptly.

-- <END-OF-FILE> ------------------------------------------------------

This key usually means "okay, I've finished talking now".  So you use
this to leave POP-11 or PROLOG, for example, or to finish talking to the
computer altogether.  Sometimes you use it to finish typing a piece of
text (for example, to the mail program). In VED this is often
redefined to mean "move to end of current line".

-- <SUSPEND> ----------------------------------------------------------

This is available only on Berkeley Unix systems and only if you are
running the C-SHELL.

This key is used if you want to keep the current program in suspended
animation. It stops running, but it isn't dead yet. You go back to the
CSH program (see HELP *SHELL). You can then run some other programs, and
later come back to the frozen one when you want by typing a single
percent sign to the shell prompt. If you suspend several processes you
indicate which one you want by giving an integer, e.g. '%3' re-starts
process 3.

Only use the <SUSPEND> key if you know what you are doing because it can
produce some very confusing behaviour.

DON'T USE IT FROM VED AT PRESENT - it leaves the terminal in a funny
state. Instead you can (on Berkeley Unix systems) get the same effect by
doing:
    <ENTER> stop
(See HELP * STOP)


-- <ERASE> ------------------------------------------------------------

This is used to rub out the last character typed.  This only works up to
the last <RETURN> typed, so you can get rid of a character before you
press the <RETURN> key, but not after.  (In VED this restrinction
doesn't apply.)

-- <KILL> -------------------------------------------------------------

This is used to rub out the line which you are currently typing. Again,
this usually only works before you press the RETURN key.

-- <WORD-ERASE> -------------------------------------------------------

This is like the <KILL> key, but deletes the most recent "word" which you
typed. (It doesn't really know about words, but it does make a good
guess.) Like the <KILL> key and the <ERASE> key, this doesn't work after
you've pressed the <RETURN> key.

-- <START> and <STOP> -------------------------------------------------

When the computer is printing lots of stuff, oftentimes it will go off
the screen before you get a chance to read it.  You can press the <STOP>
key to make it wait for you to catch up, and then the <START> key to make
it print more. Watch out for the <STOP> key -- if you press it by mistake
and don't know about it, the machine won't print anything and will look
as though it's completely ignoring you.  Try the <START> key before
panicking.

(Some terminals have a key marked 'SCRL' or 'No SCRL'. Pressing this
alternately sends a <STOP> and a <START> code to the computer.

-- <RETURN> -----------------------------------------------------------
When you are typing commands to a program or the shell, the <RETURN>
key essentially says to the computer 'I have finished typing in this
line, so take it and do what you have to with it'. The line may
give a command, or it may be some input in response to a query from
the program. Before you press the key you can "edit" what you have
just typed by cancelling some or all of it using the <KILL> key,
the <ERASE> key, or the <WORD-ERASE> key. After pressing <RETURN>
it is too late.

-- NOTE ---------------------------------------------------------------
In VED some of the keys lose their normal effects or have additional
effects.

-----<Copyright University of Sussex 1987.  All rights reserved.>-------
