CD ROM Paradise Collection 4/CD ROM Paradise Collection 4 1995 Nov.iso/program/4th86_v4.zip/TUTORIAL.TXT

Text File | 1994-01-25 | 10KB | 364 lines

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  Welcome to 4th_86 implementation of the FORTH language.

 It is recommended that you print out and read the file INTRO.4TH as this
 will explain the concept of FORTH as an operating environment. However --
 if you prefer the "learn by doing" approach -- carry on with this tutorial.

 Use keys 4 F2 N and 4 F1 N to page forward and back. At the last  page F2
 will cycle you back to the beginning page. F1 action ceases at  page 1.

             To leave 4th_86 and return to DOS type   4 BYE  N
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 The blue window is used for tutorial text. The Brown window is for you to
 enter commands and view results.

 The power of 4th_86 lies in the "integrated development environment" FORTH
 as a language permits. Do not be discouraged initially by the "strange"
 symbols used -- or the "reverse" method of inputting variables and
 parameters. You will soon adapt to this as easily as you could to i++ and
 ++i or the perverse niceties of the semicolon in the C language -- or to
 the complex printf style formatting commands in Pascal; Fortran; or C.

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 Try typing each of the following commands as you would if you were in MsDos

 **NOTE**  although commands are shown in upper case ( capital ) letters you
  can type them in either upper or lower case. 4th_86 is not case sensitive.

      4  DIR  N   4  DIR \*.SYS  N    4  5 SECDELAY  N   4  TM   N

 If you get in trouble -- use keys   4  F2 N or  4  F1 N to get  back to
 the tutorial and try again
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 Now let's try two more forth WORDS which will give you some background
 details -- but will temporarily erase the colored windows.

 Do not panic when all the tutorial instructions disappear!! You can easily
 get them back by using keys   4 F1       4 F2    -- or if that doesn't
 work, by typing   4  HELP

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 So let's try it --- type  each of the following commands -- again just as
 you would if you were in MsDos

                4  INFO   N                 4  INTRO  N

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 Here is part of the the  4 STATUS   display
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 When you are using 4th_86 seriously as a programming tool -- you will not
 usually be working in a colored window -- or half screen environment --
 though you can if you so choose.

 In this exercise; once again all the tutorial text will disappear -- but
 this time  4 F1     4 F2    will not function. Only  4  HELP
 will return you to the tutorial text.

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 Write down the following commands to try once you exit windowed mode

         4  DIR   N   4  STATUS  N   4 DDICT  N  4  FILES  N

         4  DD GOTOXY   N   4  DD SECDELAY  N

 Then type  4 FULLSCREEN  N to leave tutorial mode.
              Remember -- enter  4 HELP  N to return
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 4th_86 also allows you to use your own favorite DOS editor with a
 considerable degree of automation. You will need to configure the file
 EDITR.BAT to make this work - so let's leave that till you've read
 INTRO.4TH.

 FORTH is both an INTERPRETER and a COMPILER. It's much much more than
 BASIC is -- but let's use the concepts of BASIC and C as a starting
 point.

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   C version                Basic version
   ---------                -------------
  main(void)                10 for i = 1 to 10
 {                    20 print i
 int i;                    30 next
    for (i=1; i<=10; i++ )
    printf ("%d \n", i) ;        Forth version
 }                    -------------
                : test1 10 0 do i . crlf loop ;
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   C version                Basic version
   ---------                -------------
  main(void)                10 for i = 1 to 10
 {                    20 print i
 int i;                    30 next
    for (i=1; i<=10; i++ )
    printf ("%d \n", i) ;        Forth version
 }                    -------------
                : test1 10 0 do i . crlf loop ;
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 The C version has to be compiled and linked with a library to form an EXE
 file before the program can be executed. The file can be named TEST1.EXE.

 The BASIC version can be run in INTERPRETER mode by typing the command RUN.
 It can be saved as a file TEST1.BAS -- but this is not an executable file.
 If a COMPILER rather than an INTERPRETER is used -- an EXE file can be
 created -- but BASIC interpreters and compilers are separate utilities.

 The FORTH version is COMPILED **as it is being written**. It has a name
 TEST1 and can be immediately executed by typing TEST1. It can be saved
 either as an executable file TEST1.COM -- or source TEST1.4TH
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  You could now type in the following four FORTH definitions

  4: test1 5 0 do i . crlf loop ;    4: test2 15 0 do i . tab  3 +loop ;

   4: test3 10 0 do i . 2 spcs  loop ;     4: test4 20 5 do i . loop ;

 However we have done it for you in a file called EXAMPLE1.4TH
 so all you need do is type    4 FLOAD EXAMPLE1.4TH
 and then execute each word in turn by typing   4TEST1    4TEST2  etc
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 Note that definitions can continue over several lines
 : test1
    10 0
       do
         i . crlf
       loop
  ;

 So that once you have entered a COLON sign -- 4th_86 will attempt to compile
 every statement you make -- up to the point at which it detects a SEMICOLON

 This causes few problems if you forget the semicolon -- because 4th_86 will
 rapidly be given some text it doesn't recognise -- at which point it will
 give an error message.

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 The same applies to comment delimiters -- a CR does NOT end a comment. This
 can cause mysterious hangups as text you thought was being entered as a
 definition is being treated as an ongoing comment.

  : test5 20 0 do i . loop ;

  ( the above was test 5

    : test6 15 0 do i . 3 +loop ;

    ( that was test 6 )

   test5 has been entered as a definition. test6 however -- and any more
 text that is typed in -- is ignored by 4th_86 as a comment; because the
 right hand ) delimiter after " was test 5 " has been missed out.

  You must take care to ensure brackets match -- as do colons and
  semicolons. If 4th_86 appears to have gone to sleep -- it is most likely
  due to an unclosed comment string.
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 The same care must be taken to match double-quote marks  "  in strings

  Load the file EXAMPLE2 by typing  4 FLOAD EXAMPLE2.4TH

   Once you have loaded the file try out the words
     4  HEADER      4  FOOTER     4  DOLOOP      4  DOLOOPTEST

  As you have not yet configured EDITR.BAT -- you can use the command
    4  TYPE EXAMPLE2.4TH  if you want to view the definitions again

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    Practice printing out some strings. It can be done in IMMEDIATE
 mode ( ie -- not within a word definition ) just as in BASIC.

    Take care to leave a space after the first quote mark

    " this is a test"  ."     will print correctly

    "this is a test"   ."   will give an error message
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  Note that control characters such as LF  CR  TAB etc can be inserted
 inline provided they are enclosed by up-arrow delimiters

  " this is ^9^ a test ^0dh 0ah^ to see ^13 10^ what happens " ."

    The 9 represents TAB.  CR is either 0dh ( hex ) or 13 ( decimal )
                           LF is either 0ah ( hex) or 10 ( decimal)

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 Here are the definitions you've entered to date.
ddict 
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  Go back to the previous screen and select a word somewhere in the middle of
  those listed under USER DEFINITIONS -- then return to this screen

  Let's suppose the word you chose was HEADER

   type  4  FORGET HEADER

  and again return to the previous screen
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  You will find that HEADER and all the words defined after it have
  now been deleted from 4th_86.

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  Now let's define a new word -- type in
     4  : new-word " this is a test " ." ;

   you can make sure it works by typing  4  new-word

   Now let's try to re-define the same word
          4  : new-word " this is not another test " ." ;

    when you get asked if you want to redefine -- answer Y

    Now test by again typing   4  new-word

    type  4  forget new-word   and then  4  new-word

    you will see that the original definition has been restored

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  by now you should be reasonably comfortable with how 4th_86 functions
    ( see next screen for window manipulation commands )
  repeat the last screen if unsure -- and then type

     4  w2    followed by  4 splitat 0      and

     4  ddict
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    Now define and redefine some words -- use DDICT to examine the
 dictionary -- FORGET some words and use DDICT again.

    If you're feeling really brave, leave thhis tutorial by
 typing  4  fullscreen  N  and enjoy the freedom of a full size screen.

    Configure EDITR.BAT and ASMBL.BAT and work through the examples
 in the documentation.

    You can always return to windowed mode by the words
     4  splitscreen  N  or  4  help  N
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    W1  places cursor in upper window
    W2  places cursor in lower window
       W1INIT and W2INIT clear windows
    SPLIT divides windows equally mid-screen
    SPLITAT N divides windows at line N
       ( if N > 23 it's truncated to 23 )
        SPLITSCREEN is the same as SPLIT
        FULLSCREEN is the same as UNSPLIT

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    The source code for the tutorial / windows is included
    as 7TUT04.4TH

    All source code is pure ascii and can be printed as-is
        or edited with any ASCII type editor.

    examine the code to get further ideas of how to use FORTH

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