Shareware Grab Bag/Shareware Grab Bag.iso/007/forth83.arc/F83.DOC

Text File | 1984-06-20 | 7KB | 150 lines

.PO 3

    WELCOME TO FORTH

     This   is  a  public  domain  system,  and  may  be   freely
distributed  and copied, as long as the authors are given  credit
and  no copyright notice is placed upon it.  If we catch  someone
selling this system as their own proprietary product, with  their
copyright notice , we will do our best to make them regret it for
the rest of their lives.  You have been warned!!

     By  now  you may have looked at some of the files  with  the
cp/m TYPE command.  You can have a printout of these instructions
by using Control P and entering  TYPE FORTH.DOC

     In  what  follows the <CR> symbol  represents  the  carriage
return  key  on  your terminal.  To enter  Forth  from  the  CP/M
environment,  insert  the disk containing the F83.COM  file  into
drive  A of your computer, (after booting it of course) and  type
F83<CR>

     Forth will reply with:

8080 Forth 83 Model 1.0.0
Modified 11Oct83


Forth is about ten years old now (1983) but some of the  features
of F83 are relatively new to the Public Domain Forth Model.

     The  VIEW command is one of the best. VIEW <word> <CR>  will
find  the screen that contains the code for the <word>,  provided
that  the  file that contains <word> is on the  currently  logged
disk  drive.  If you can fit all of the source code on  a  single
drive,  VIEW works great, and takes care of opening the file  and
displaying the screen for you.

     We  have  also  tried to make extensive use  of  the  shadow
screen  concept.  In this regard, the A word moves you  from  the
current  screen  to  it associated  shadow  screen.   The  SHADOW
vocabulary  contains  a  bunch  of  words  that  are  helpful  in
maintaining  shadow screens.  COPY allows you to copy not only  a
screen, but also its associated shadow.  SHOW allows you to  list
each source screen across from its shadow when you want to  print
them.   Finally CONVEY allows you to move groups of  screens  and
their  associated shadows.  To see what words are in  the  SHADOW
vocabulary simply type SHADOW WORDS<CR>

     There  is  also  a decompiler  present  which  reverses  the
compiling  process, producing source code from object code.   The
user  interface to it is the word SEE <name> where <name> is  the
name  of  a  Forth  word  you  wish  to  decompile.   While   the
information  SEE  gives you is not as complete as that  given  by
VIEW,  a  least it is always available, and  not  dependant  upon
whether  or  not  the correct file is present  on  the  currently
logged in disk drive.  For a real experience try decompiling  the
words STATUS, which is a DEFERred word, ie and execution  vector.
SEE  calls  itself recursively in this case and tracks  down  the
definition.  This can be quite handy.

     To  see a list of the words that are in the dictionary  type
WORDS.   You will see lots of words.  Each is a command and  each
can be VIEWed.  Let's look at the word SHOW by typing VIEW  SHOW.
Assuming  all is well you will see a Forth screen containing  the
definition  of SHOW along with some other words. Type  A  L  (cr)
and  you will be rewarded with the Shadow screen that  goes  with
it.   A  L  (cr)  will Alternate List you back  to  the  original
screen of code.  Look at it and when you see a word that  doesn't
seem fully self evident, VIEW it and read the shadow screen.  The
word  SHOW and it's source code that we have been viewing,  is  a
command  that  prints out three source screens along  with  three
shadows  for  a  total of six screens per page.   There  are  two
versions of SHOW.  The vocabulary you are in determines how  SHOW
will print out.  If you are in the SHADOW vocabulary, six screens
of  code  and shadows will print.  If you are in FORTH  all  code
screens will be the mode.

     Now  for  some more commands.   N is next screen  and  L  is
list.  N L  lists the next screen and  B L lists the next  screen
back.   N ED will edit the next screen etc. Now lets  printout  a
few  screens that will detail some of the editor  commands.  Most
are from Starting Forth but some are new ones.

Type this: EDITOR VIEW JOIN<CR>

You are looking at a screen of editing commands.  Lets go to  the
shadow  with the  A L  command and do some exploring.   While  we
are  in  the  shadows lets look at the next five  or  six  shadow
screens  that  should be editor words.  Use N L.  If you  have  a
printer  you may print these screens now as follows.   Type  VIEW
WIPE  for example.   If wipe is the first of 6 screens of  editor
words remember the screen number.  If for instance it was 80 then
type  80 85 SHADOW SHOW<CR>

     If  you  are new to Forth your best bet is to  purchase  the
book  STARTING  FORTH by LEO BRODIE.  It  costs  about  seventeen
dollars  and is available at most large book stores.  On page  84
you  will find the commands for the line editor.  The  F83  model
follows both the book and the Forth 83 standard.

     The  Forth  Interest Group ( FIG ) has meetings on  the  4th
Saturday  of  each  month, currently at  the  Chabot  College  in
Hayward,  CA.  Call the FIG hot line if you wish to double  check
the location ph 962-8653 or the FIG Tree BBS (300 baud)
at 538-3580.

Henry Laxen                                  Mike Perry
1259 Cornell Avenue                          1125 Bancroft Way
Berkeley, CA 94706                           Berkeley, CA 94702

.pa
             Standard System Documentation Requirement

1.  The  system  dictionary space is CPU  dependant  and  can  be
determined by typeing HERE U. <CR>

2. The application dictionary space is also CPU dependant and  is
the  difference  between  the  top  of  the  dictionary  and  the
beginning of the parameter stack.  The location of the  parameter
machine.   The application dictionary space can be determined  by
typing SP@ HERE - U. <CR>

3. The data stack space is the same as the dictionary space.

4.  The return stack space was arbitrarily set at 256 bytes.   It
can be altered by remeta-compiling the system.

5.  No  mass  storage block ranges are reserved  by  the  system,
other than the contents of the files that are distributed.

6. The user has available to him blocks 0 thru 65534.  Note  that
block  0  may  not be used for loading.  Block  number  65535  is
reserved to indicate the buffer is missing.

7. Any ascii terminal should work with this system.  If the  user
has  a  cursor  addressable terminal, the editor  can  be  easily
modified to take advantage of the terminal's characteristics.

8. System action taken upon error conditions:

     ' <name> ['] <name>  not found results in ? error message

     */ */MOD / /MOD MOD UM/MOD  all division by 0 errors  result
     in a 0 quotient

     : in the case of an error, a ? error message will be printed

     DO if a nesting error occurs, the system will crash. (if you
     are lucky)