No Fragments Archive 10: Diskmags/nf_archive_10.iso/MAGS/STOSSER/STOSSE04.MSA/TUTORIAL.DOC/TUTORIA2.DOC

Text File | 1987-04-22 | 9.8 KB | 411 lines

           STOS BASIC 4

I assume little/no prior knowledge
of Stos.  Each lesson will also have
a Stos BASic or ASCii file to go
with it.

Listed here for your convenience.
I.E. to make it easier to write them
down or to look at the structure of
the command. Are the new commands to
be dealt with.

LOAD     SAVE     DIR$    RESERVE
BAS      ASC      MBK     PI!
CLS      NEW      CLEAR   WAIT
APPEAR   DELETE   MODE

Do not worry if you find things hard
at first, practice makes perfect.

Actual progs are used to explain
things, called 'name.asc' and
included in this folder.  First how
to load and save files, then other
the commands.

If you have any problems, then look
for the command on pages 271/73 of
the manual.  This is not intended to
replace the manual, but to add to it
where needed.


LESSON ONE:

loading & Saving normal files.

Name = The name you give to the
        file.

Type = The type of file it is.

Load"name.type"
Save"name.type"

Types of files:

ASC = a file saved (as text only).
BAS = Stos Language file.
MBK = single memory bank file.
Pi1 = degas low res picture.


Files ending in '.ASC' are files
which just store the character
details.  Try to open one from
desktop.  You can read these files,
but you can also load them into
STOS.

Files ending in '.BAS' store details
of Stos which can only be loaded
into STOS.  Try to open one from the
desktop and you will only see a lot
of gibberish.  This is the format in
which Stos stores its files.  This
can be text as well as whatever is
in the memory banks.

ASCII files only store the text.


The BASic file, will store the
picture and the code together as one
file, but I am going to show you how
to store them on their own as well.

But first the code ( T4LES1.ASC)

10 rem this loads a picture to
       screen
20 rem and to bank 6
30 rem it then tests for screen res
40 rem and loads the picture from
       bank 6 to screen
50 cls
60 dir$="\stos"
70 load "pic.pi1"
80 reserve as screen 6
90 load "pic.pi1",6
100 print "press any key"
110 wait key
120 if mode<>0 then mode 0
130 appear 6
140 dir$="A:\"

Ok.
lines 10-40 are not read by the
computer, and are there just for
your use.  I.e. so that you know
what to expect.

line 50 CLS

this clears the screen removing
anything not wanted on screen.  Not
really that important here, but it
is good practice to use the CLS
command.

line 60 dir$="\stos"

This is important.  It tells STOS
where to look for the picture file
on disk.  Notice the BACKSLASH '\'
it wont work if you miss it from the
command.

line 70 load "pic.pi1"

This loads the file to the screen,
from within the STOS folder on your
language disk. It looks for a file
called 'PIC.PI1'.  If not found the
programme will stop dead. If you
were in medium res then the picture
is somewhat scrambled.  Do not
worry, it will sort itself out soon
enough.  Notice that the file name
and file type are separated by a
full stop and not a comma.

80 reserve as screen 6

This reserves a memory bank as a
screen bank, and allows you to load
pictures into that bank.  It also
allows you to save them as well as
moving them about.

90 load "pic.pi1",6

You should have an idea about this
line.  It loads the same picture
into bank 6.  Notice the comma
before the number.  It wont work if
you miss the comma off.

100 print "press any key"

This just tells you that the
computer is waiting.  You could use
the LOCATE command discussed in the
previous three tutorials to place
this in a better spot, but I wanted
to keep this simple.

110 wait key

This tells the computer to wait for
a keypress before continuing.  WAIT
100 could have been used to pause
for a short time, where upon the
computer would have waited a short
while before moving on.  But I
wanted you to know what is happening
and why.

120 if mode<>0 then mode 0

This line would normally appear near
the start of a programme.  It checks
to see if the screen is set to low
res or not.  If it is then nothing
happens, if not then it changes to
low res.  The mode being how many
dots appear on the screen.  More
dots means a better picture, but
less colours.

130 appear 6

This command makes the contents of
bank 6 appear to the screen.
However, if you move the mouse
around, then you will see that the
picture starts to disappear.  Do you
know why?  Well it is because the
appear command only places the
picture to the physical screen.
There is a Logical and background
screen as well. But as this is only
about loading and saving, I am not
going to go into the different
screens.  That will come in a couple
of tutorials time.

140 dir$="A:\"

This resets Stos to the root
directory of drive 'A:'.


[ ] is used to enclose direct
commands where you copy everything
except the [] and then press either
the RETURN or ENTER key.

It does not matter whether you use
capitals or not, but you must enter
everything enclosed within the [ ]
paying attention to full stops and
commas.

To load the file you type [LOAD
"T4LES1.ASC"]

Then enter [LIST] to have a look at
what has been entered.

Now we are going to save the file.

Type [SAVE"TRASH1.BAS"] or press
[F4] and type in the name and press
return.

Now enter [MODE1]

The screen should have changed, and
the writing on it should be smaller,
as we are now in medium resolution.

now enter [RUN]

It should have loaded a picture from
disk and displayed it to screen.
Because the picture is in the wrong
resolution it displayed a scrambled
picture to screen.

Then it waits for you to press a
key, before changing resolution and
moving the picture from bank 6 and
displaying it to screen.

So now you know what happens if you
use the wrong picture and screen
resolution.

enter [DIR]

Pay attention to the files on disk.
DIR displays the DIRectory contents
of whichever folder you are in at
the time.  Now delete line 140 by
typing DELETE 140 and pressing
return.  You could also just type
the 140 and press return to delete a
single line, as line numbers without
any code are not entered but are
deleted instead.

Now save the file as "TRASH2.BAS".
and use the DIR command again.  This
time the contents are different, and
there is no TRASH1.BAS.  Do you know
why?  Well, it is because you are
still in the STOS folder, and that
is where you have saved to.
TRASH1.BAS is out side of the
folder.

We have done three very important
things now.  We have learnt how to
load, how to save and how to move
from one folder into another within
Stos.

But now for something a bit easier.

enter [Dir$ = "A:\"]

enter [LIST]

You should see the lines of code
from 10 to 130, or to 140 if you did
not delete the last line, plus
memory bank 6.  Which if you
remember holds the picture.

Now, how do you get rid of what's on
screen?  Well if you just want to
tidy up the screen then you would
use the CLS command.

enter [CLS]  then [LIST]

You should see the same as before.

But what if you wanted to get rid of
the memorybank but keep the code or
perhaps the other way round.

enter [CLEAR} then [LIST]

To dispose of the memory banks you
use the CLEAR command.  This
disposes not only of all the banks
but also the value of all variables
as well - in this case we do not
have any variables so it does not
matter.

There is a way to get rid of just
one bank at a time, but that will be
discussed next time.

However, what if you wanted to keep
the banks but get rid of the code?
Well in that case you would use the
DELETE command.

enter [LOAD"trash1.bas"]

Now enter [list]



Now we start on something a bit
different. type [NEW].

Now type [DIR]  if you are not in
the root directory, then type [DIR$
= "A:\"] to move there and load the
trash1.bas file again.

Now to add some more lines to it.
150 SAVE "TRASH3.BAS"
160 SAVE "TRASH1.mbk",6
170 ERASE 6: SAVE "TRASH1.BAS"

You have now saved the picture to
disk from bank six, or you will have
when you run the programme.  Once
you have [RUN] the programme then
[DIR] again.

You will see something interesting.
Trash1.bas is not the same size as
trash3.bas.  And there is also a
trash1.bak file as well.

This is the important part of the
whole lesson.  Stos makes duplicates
of the BASic files when you save
them more than once, but it does not
do this to the other files.  So
what?  Well if you are pushed for
space on disk, you do not really
want the memory banks to be saved
twice, so it is better to split them
and save each separate.


Now, type [NEW] then
[LOAD"TRASH1.MBK,6"] then [LIST].

Notice the comma after MBK, and the
full stop before it, and that the 6
is included within the quotes.

You will see that there is no BASic
file, but there is a memory bank
file which is bank 6.  Stos tells
you it is a screen bank by its name,
but there are ways of saving screens
to banks other than as screen banks.

NOW type [APPEAR 6]

then move the mouse around the
screen.

Now type [CLS] then
[LOAD"trash1.bas"]

Then [LIST]  Then [APPEAR 6]

You will find that the memory bank
has been erased.  This is because
Stos deletes everything and erases
everything when it loads a BASic
file.

Now type [LOAD"trash1.mbk,6"] again.
and then [LIST].

This time you will see that the
Basic code has not been deleted, and
that the memory bank 6 has been
loaded.

Type [APPEAR 6] to make sure that it
is there.  I assume that you know
how to change resolution if you are
in medium res.  [MODE0] if you have
forgotten.