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TEACH VT100                      Steve Hardy and Aaron Sloman Dec 1982

=== TEACH for VT101 terminals ========================================

Welcome to TEACH, which will help you to learn how to use POP11. TEACH
displays text in 'teach files' stored on the computer's magnetic disk. You
are now reading a teach file.

On the top row of the keyboard are four keys marked with arrows; the one
marked with a downward arrow is called the DOWN-SCREEN key. Press the
DOWN-SCREEN key twice; do not hold the key down - press and release
immediately - and TEACH will display the next portion of this file.

Next to DOWN-SCREEN is the UP-SCREEN key, marked with an upward arrow.
Press UP-SCREEN twice, to return to the beginning of this file and then press
DOWN-SCREEN twice to return here.

Press UP-SCREEN then DOWN-SCREEN alternately. You will see the 'cursor' -- a
white oblong -- move up and down. If it is at the top of the visible portion
of the file, pressing DOWN-SCREEN makes it jump to the bottom. If it is
already at the bottom, DOWN-SCREEN brings the next portion of text into view.
Now press DOWN-SCREEN (once or twice, as needed) to read on.

UP-SCREEN works similarly. It moves the cursor to the top of the visible text
unless it is already there.  If the cursor is at the top, UP-SCREEN takes you
back to the previous portion of the file. You can think of the screen as a
window, through which you can see a part of the file.  UP-SCREEN and
DOWN-SCREEN bring new sections of the file into view.  They always leave one
line of the previous screenful visible, to help you keep your bearings.

Use the UP-SCREEN and DOWN-SCREEN keys as appropriate to read the rest of
this file. Make notes as you go, to help you remember what you read.

Be careful when pressing UP-SCREEN and DOWN-SCREEN; if held down (rather
than being pressed and released) these two keys (and most of the others)
behave as if they are being pressed repeatedly.  Holding them too long will
move you several screenfuls instead of just one.

-- WHO's WHO --------------------------------------------------------------
Although your terminal is always connected to the same computer, the computer
takes its instructions from you by means of several distinct programs. These
programs accomplish different things for you, and you give them commands in
different ways.

For instance, before you logged in you had to talk to the login program, which
only knows about user names and passwords. After you had logged in and got the
colon prompt ':', you were talking to POP11. Since you don't yet know much
about the POP11 language, you could only type

which got you talking to TEACH. TEACH is actually a guise of the POP11 text
editor VED, with which you can create and modify your own files.  You will
learn about more of its commands when you read TEACH VED later on. So far you
have tried out the commands UP-SCREEN and DOWN-SCREEN. The diagram below
shows the route from logging in to where you are now.

        LOGIN  <-> POP11 <-> TEACH (using the EDITOR)
                            |You are here|

-- GOING BACK TO POP11 ------------------------------------------------------

Later on, you will often want to stop reading a file and try out some
commands in POP11. Right now the only command you know how to give POP11 is
the teach command, but you can use that to practise going back and forth.

First you will leave TEACH. This takes you back to POP11, which prints a
colon prompt (":") at the bottom of the screen to tell you it is ready. Then
you can type "teach" and press the RETURN key to tell POP11 you want to come
back to TEACH. Detailed instructions now follow. Their end is marked by a row
of asterisks. Read them all (jotting down notes if necessary) before carrying
them out.

To tell TEACH you have finished, you give an ENTER-x command. (Think of X for

This is done by the following sequence:

    (a) Press the key marked ENTER (lower right of the keyboard)
        Notice that the cursor moves to the line above the displayed text.
    (b) Press the key marked 'x' (left end of the bottom row of letter keys)
    (c) Press the key marked RETURN (at the right of the bank of letter keys)
After a short pause, POP11 will prompt you with a colon. Tell POP11 to send
you back to TEACH by typing
and then pressing the RETURN button. TEACH will display the same portion of
text that was showing when you did ENTER-x. Now try going to POP11 and
returning to TEACH.

Notice how, when you come back to TEACH, whatever was on the screen
before is shifted up, so that you can still read it.

You can tell when you are giving commands to POP11 because it prompts with a
colon at the left of the line where the cursor is. If there isn't a
colon then you must be talking to TEACH.

Try all that again.  Leave TEACH with ENTER-x, then type
followed by the return key, to POP11. (If necessary, you can first use the
UP-SCREEN key to go back to the detailed instructions.)

Soon you will practice logging out and logging in again.  However, each time
you log out and come back, you start afresh.  There is no record kept of what
you were doing previously. So before you log out, it will be useful to know
how find the place where you left off in this teach file.

-- THE COMMAND LINE -----------------------------------------------------
The line above the text, to which the cursor jumped when you pressed the
ENTER key, is called the 'command line'.  You may have noticed that it
contains, among other things, a number.

The number on the command line indicates which line of the teach file the
cursor is currently on. If the cursor is on, say, the 121st line of the teach
file, then the number will be 121. Try pressing UP-SCREEN and DOWN-SCREEN a
few times to see that the number changes. The command line also reminds you
of the name of the file you are reading.

-- JUMPING TO A LINE IN THE FILE ------------------------------------
The command line is so called because you can use it to give commands to
TEACH.  You have already given an ENTER-x command, typing an 'x' on the
command line.  You can also give an ENTER command to get to another
line in the file. For instance, you can go to line 1, the beginning of the
file, as follows:
    (a) Press the ENTER key     (cursor goes to command line)
    (b) type the number, using the keys at the top of the keyboard, NOT
        the keys in the cluster on the righthand side.  The '1' is next
        to the top left.
    (c) Press the RETURN key

When you have done that, repeat with different numbers, ending with the
number of the line you are on now, so that you can come back here.

-- LOGGING OUT ---------------------------------------------------------

Before carrying out any of the instructions which follow, read all the way
up to the line of asterisks below.

To log out you will have to

    (a) get from TEACH to POP11, by giving an ENTER-x command
    (b) logout by giving a BYE command.

The whole sequence is:
    (a) press ENTER        \
    (b) press x             )communicating with TEACH
    (c) press RETURN       /
        You should then be prompted by POP11 with a colon i.e. ":"
    (d) type               \
        bye                 )
    (e) press RETURN       /  communicating with POP-11

After logging out you'll have to press the RETURN key to 'wake up' the
computer, before you can log in again.

When you log in again after logging out, TEACH will not remember what you
had been doing before. So you should make a note of the line number you want
to return to.

When you log in, you'll get the colon prompt telling you that POP11 is ready.
You can then type TEACH and press RETURN. It looks like this:
    USERNAME: <your username>
    --- various login messages ----
    --- POP11 prints a welcome message ---
    : TEACH

That will tell TEACH to get this file back for you to read. Then use
the ENTER-(line number)-RETURN sequence to get back to the line you want.

Now try logging out, then log in again and come back to POP11, then to TEACH,
and then to this line. (Use the UP-SCREEN key to go back and re-read the
instructions for logging out: ENTER-x, then BYE.)

-- OTHER TEACH FILES -----------------------------------------------------
There are teach files on many different topics. You can ask to transfer
temporarily to another teach file and then come back to this one. For
instance, there is a teach file called WINDOW, which will show you how to
enlarge the visible window so that you can see more of the file at once. To
read it:

    (a) Press the ENTER button    (Cursor moves to command line)
    (b) TYPE:  teach window       (If you make a mistake use the DEL key)
    (c) Press the RETURN button   (This means: now do the command)

This will get you the TEACH WINDOW file. Try it, and obey the instructions.

-- THE KEYPAD ---------------------------------------------------------------
    |  PF1  |  PF2  |  PF3  |  PF4  |
    *-------*-------*-------*-------*       This is the layout of the
    |   7   |   8   |   9   |   -   |       keypad at the right of the
    *-------*-------*-------*-------*       keyboard.
    |   4   |   5   |   6   |   ,   |
    |   1   |   2   |   3   |       |
    *-------*-------*-------* ENTER |
    |       0       |   .   |       |
When you are talking to TEACH (but not POP11), the numbered keys on the
keypad can be used to move the cursor by a single step in eight different
directions, which you will find useful later when you are typing in your own
programs and reports.

The key marked 2 moves the cursor down just one line; if the cursor is at the
bottom of the screen then one fresh line of text is displayed. The key marked
8 moves the cursor up a line. Try those two keys and notice the effect on the
number in the command line.

Get the following plan of the number keys all visible at once on the screen,
using keypad-2 if necessary.
Experiment by pressing the keys     |7   UP  |8   UP  |9   UP  |
and see how the cursor can be made  |   LEFT |        |  RIGHT | Can you put
to move in any of eight directions. |________|________|________| the cursor in
                                    |4       |5       |6       | box 5? Then in
                                    |   LEFT |  CENTRE|  RIGHT | box 9?
                                    |1  DOWN |2  DOWN |3  DOWN |
                                    |   LEFT |        |   RIGHT|

If you try to move the cursor up or down past the boundary of the window,
the file scrolls down or up, as if you were pushing the window in the same
direction as the cursor.

You'll find that if the cursor is at the left of the screen and you try to
move it further left, (using key 4) then it will jump to the end of the
previous line.

You can make the cursor take bigger jumps if you press the ESC key before
pressing the number key. E.g. try ESC 4, and ESC 6 a few times. Don't press
the keys simultaneously. Then try ESC 3 and ESC 7 a few times.

You may also find it useful to know that the key marked LINE FEED, to the
lower right of the RETURN button, makes the cursor go to the beginning of the
next line down.

--MOVING THE CURSOR A WORD AT A TIME ------------------------------------
Two of the keys are known as WORD-LEFT and WORD-RIGHT. These are the two keys
marked '0' and '.' on the keypad, immediately to the left of the ENTER key.
Press them a few times each, and see what happens to the cursor.

See what happens if you press WORD-LEFT when the cursor is at the beginning of
a line.

-- REFRESHING THE WINDOW -----------------------------------------------------

Occasionally, the text displayed on your screen may become jumbled. One
possible cause of this would be someone tripping over the power lead
connected to your terminal. If this happened, then your screen would go
blank (and stay blank even when the power was restored) until you tell the
computer to refresh the contents of your screen. You can do this by
pressing the key marked 'PF1' (at the top left of the keypad) twice.

For now you can ignore the other keys on the keypad, apart from ENTER, which
you use for putting the cursor on the command line in commands like
ENTER-x, ENTER-teach and ENTER-(line number).

--SCREEN LEFT and SCREEN RIGHT -------------------------------------------
You may have guessed the function of the two keys with arrows pointing left
and right by the UP-SCREEN and DOWN-SCREEN keys. Try them, after first
making sure that the cursor is on a line which is not blank.

-- REVISION -----------------------------------------------------

You should make notes of all the important points concerning the use of
TEACH and check with your course tutor about any confusions. Here's a brief

    How do you move the cursor about the teach file?
    What does the ENTER key do?
    What does pressing the ESC key then 'w' do?
    What does pressing the ESC key then 'q' do?
    What does the ENTER-x command do?
    How do you switch between POP11 and TEACH?
    How can you tell which one you are talking to?
    How do you expand the TEACH window?
    How do you refresh your screen?
    How do you LOG OUT?
    Which keys move a word left or right?

Your next teach file should be TEACH VED, to find out how to use the text
editor to make your own files. If you log out now, log in as before when you
come back, except that when you have got the POP11 colon prompt you should
    teach ved
then press RETURN.