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This is the file README and belongs to version 0.9.4a of May 8, 1994
of the portable Forth-environment.
--------------------------------------------------------------------
What is it?
===========
This package contains all neccessary ANSI-C source files to build a
running Forth-environment on most UNIX machines, on DOS and on OS/2.
The Forth-system is closely modeled along the new American National
Standard for the programming language Forth. I implemented every word
of every word set mentioned in the dpANS-6 document of june 1993.
Additionally it is compatible to Forth-83.
This set of source files is distributed under the GNU general public
license for libraries. See the file COPYING.LIB for conditions.
I chose that one to point out that I don't consider programs you write
on top of it a 'derived work' of the portable Forth environment. To
violate these conditions you have to do two things together:
- you use a modified pfe to run your program
- you keep these modification secret
Should be easy to avoid.
Why did I do it?
================
For fun. As an excercise in unix programming. And there was no such
thing. See below, design objectives.
Design objectives
=================
With two elaborate standards at hand, one for C, one for Forth, it
should be possible to build one language in terms of the other and
thus provide both where at least one is available.
While I leave the writing of an ANSI-C compiler in Forth to those who
really believe in Forth's superiority and universality, I concentrated
on the manageable part: Providing a Forth-system in ANSI-C that is
- CORRECT this means not just "no bugs" -- it means all
the interaction of all parts works as specified
by the standard AND by traditions.
- COMPLETE with powerful computers on the desk and power-
ful programming environments there is no need
to and no use in strategies like "here kernel,
there xyz word set" that might be appropriate
on a microcontroller.
- PORTABLE I hate to rewrite code because of environmental
dependencies. Most of the system should be a mere
interface between two well defined languages.
There are of course such dependencies. I tried
to resort to a common subset of all UNIX bahavior
known to me. Fortunately this in fact allowed
porting to DOS and OS/2 thanks to the great
emx-package.
- USABLE A sole kernel helps noone. It should be a
development environment. You should be able
to manage multiple-source-file-projects from
within.
- SIMPLE or transparent. At least to my taste.
Maybe you miss the design objective SPEED. It was not my goal to
provide the fastest C-based Forth-environment. This would have led to
conflicts with much more important goals. We all have fast computers,
haven't we?
After all pfe isn't slow. With a little tuning using GNU-C's global
register variable feature it is pretty fast. But obviously it cannot
compete with assembler implementations.
Status
======
Did I achieve the above objectives?
Some of them. I'll continue working on it.
The system is in use for fifteen month now. Several quite obvious and
several quite subtle bugs have been fixed. While there surely are some
more, they are not as obvious since the system passes several test
programs, some of them rather sophisticated.
Once you get the system running, you'll have
- All ANSI Forth word sets with the exception of the assembler
hooks `CODE', `END-CODE' etc. Nothing else is missing.
- Several more words provided for compatibility and convenience.
- An interface to a text editor to edit plain text sources
and the ability to include them.
- A word star lookalike block file editor to write
source in the old style block format.
- A simple source level debugger -- maybe I should better
say "single stepper".
Thus you'll be able to edit, compile an run programs in a moderately
comfortable way. For the final design of the development environment
your suggestions still are welcome!
If you try this system, please keep in mind that it is still under
development. Sometimes new --even stupid-- bugs are introduced while
enhancing functionality or while fixing old ones. I appreciate every
hint to a bug and I fixed every bug I've been told about in the last
months. So please don't hesitate to tell me about whatever seems
wrong. Please check for the latest version via anonymous ftp from
roxi.rz.fht-mannheim.de:/pub/languages/forth/pfe-?.?.?.tar.gz
(accessible from germany only) or
sunsite.unc.edu:/pub/languages/forth/pfe-?.?.?.tar.gz
Please send suggestions and bug reports via e-mail to
duz@roxi.rz.fht-mannheim.de
Usage
=====
For installation refer to the files `install' and `tuning'.
Once you have it running and see the "ok" prompt after typing return
you can interactively type in forth words. If you mistype, you can
edit the command line and recall old command lines with the arrow
keys. (If you can't then your termcap doesn't work all right and you
can resort to wordstar-like control keys.)
To write some more statements try "EDIT-TEXT filename". This will
invoke your favorite text-file editor on the given file. If it
doesn't, first check the environment variable EDITOR, then check the
file "const.h" for the #defined symbol "EDITOR".
Having written some code you can load it by "INCLUDE filename".
If you prefer the old style block files, give a file to use as
block-file with the -b commandline option. Alternatively you can say
`USING filename' or if the file doesn't exist yet: `USING-NEW
filename'. Then you can edit a block by `n EDIT-BLOCK'.
If your termcap-mechanism works well, the arrow keys and some other
function keys should be active. Quit the editor with ^U and load
blocks with "n LOAD". If it doesn't work well you might not even get a
picture.
For more commandline options try the option -h.
The interrupt key is remapped to ^U and leads back to the FORTH input
loop. Use it to break out of infinite loops.
To terminate the system, type BYE at the command-prompt or press the
keyboard quit key of your system (usually ^\).
Documentation
=============
I started writing a documentation in texinfo format. This will allow
you to view it online or print it in good quality. There's also an
outdated and hopefully soon superseded man-page that explains some of
the command line options. All documentation is highly unfinished.
For more information please try to get the dpANS-document, which is
an EXCELLENT REFERENCE to this system! You can (could?) ftp it at
ftp.uu.net in the directory /vendor/minerva/x3j14.
Contributions
=============
are welcome! After the kernel is finished now it makes much sense to
share the burden of creating and improving a well rounded programming
environment for all tasks a Forth programmer wants to do. PFE is YOUR
tool. Get involved in it's design!
There is a mailing list on pfe which you should subscribe to if you
want to be up to date with the development of the system. Send e-mail
to duz@roxi.rz.fht-mannheim.de if you want to subscribe to that
mailing list.
Acknowledgements
================
I want to express my gratitude to the people who put their efforts in
the precise descriptions I found in these documents:
- draft proposed American National Standard -- Programming Languages
-- Forth (X3J14 dpANS-6, June 30, 1993)
- FORTH-83 Standard (August 1983)
- fig-FORTH Installation Manual -- Glossary, Model, Editor
(Version 1.3, November 1980)
Thanks for providing superb development tools:
- Richard Stallman and the FSF, Linus Thorvalds and all who
contribute to Linux and Eberhard Mattes.
Several nice people gave me valuable hints to bugs and possible
improvements, were patient enough to try the very first releases, made
ports to machines I never saw myself and kept me from frustration. If
pfe is stable now it is thanks to it's users. Most notably:
Lennert Benschop, Sean Conner, Holger Dietze, Kevin Haddock,
Rob Hooft, Giorgio Richelli, Marko Teiste, Guenther Thomsen.
Thank You.
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