Re: tethered Forth

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.forth
Subject	Re: tethered Forth
Date	2013-09-07 15:05 -0700
Organization	Nightsong/Fort GNOX
Message-ID	<7xr4d0mgn6.fsf@ruckus.brouhaha.com> (permalink)
References	<7xli38v3gj.fsf@ruckus.brouhaha.com> <vbWdnYxqlI_HErbPnZ2dnUVZ_q-dnZ2d@supernews.com>

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"Elizabeth D. Rather" <erather@forth.com> writes:
> FORTH, Inc. has used tethered cross-compilers exclusively for embedded
> systems programming since the mid-80's. 

Oh cool, so you don't use target-resident interpreters at all any more?
Interesting.  

> there was a considerable learning curve .... A lot of this learning is
> captured in the proposed cross-compiler standard,

I did look at that and it seemed doable though there was an issue or two
that I didn't completely understand.

> although the present documents omit any discussion of the design and
> operation of an umbilical link,

Is that considered secret sauce, or is it just a matter of it not being
standardized yet?  Are there any publications?  I had been thinking in
terms of hacking up the gdb remote stub that is typically available for
target processors these days, to handle the target-side communications.

> The only real disadvantage I know of is that it's more difficult
> technically to develop a tethered cross-compiler as a DIY project 

Yeah, that's the main part I wondered about.  It also seems to me that
the language has to be restricted a little, since you (e.g.) can't have
target words running and affecting the compilation of later words the
same way, or launching defining words or whatever.  But I hope this
isn't an issue in practice.

> For someone using one to write an embedded application, it's a pretty
> nearly ideal programming environment.

This sounds cool.

> If you're developing for a high-volume target that needs an absolute
> minimum amount of RAM, I would recommend using a target board during
> development that has generally the same configuration but more
> RAM. Your final code can be all resident in ROM or flash.

That makes sense.  I had figured the tiniest processors aren't really
feasible targets because the stacks eat a fair amount of ram.  I think
some AVR's have only 24 bytes or so of ram, but they have a lot of
registers (well, 32 minus a few special purpose ones).  Maybe a smart
enough optimizing compiler could get rid of most stack operations and
slots, using the registers instead.

> I'd really recommend that you spend some time using one of the
> available evaluation systems to get a good feel for what it's like!

One of these days I'd like to watch an expert hack on Forth code for a
while.  The thought processes seem different than other languages, which
is one of the reasons I find Forth interesting.

Regarding the evaluation systems, it's not real clear to me how one
targets the system to a specific board.  Are there docs about that?

Thanks!

Thread

tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-07 12:25 -0700
  Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-07 10:40 -1000
    Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-07 15:05 -0700
      Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-07 17:09 -0500
        Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-07 15:38 -0700
          Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-08 02:09 -0500
      Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-07 22:21 -1000
        Re: tethered Forth Lars Brinkhoff <lars.spam@nocrew.org> - 2013-09-08 11:39 +0200
        Re: tethered Forth "Ed" <invalid@invalid.com> - 2013-09-09 22:42 +1000
        Re: tethered Forth Matthias Koch <matthias.koch@hot.uni-hannover.de> - 2013-09-16 15:16 +0200
          Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-16 07:20 -1000
  Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-07 16:13 -0500
    Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-07 18:00 -0700
    Re: tethered Forth Brad Eckert <hwfwguy@gmail.com> - 2013-09-08 11:00 -0700
      Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-08 08:55 -1000
        Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-14 15:59 -0700
          Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-14 17:56 -1000
            Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-15 22:27 -0700
              Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-15 21:18 -1000
                Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-16 22:46 -0700
                Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-17 02:45 -0500
              Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-16 03:19 -0500
          Re: tethered Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-09-15 12:56 -0500
          Re: tethered Forth Brad Eckert <hwfwguy@gmail.com> - 2013-09-15 19:47 -0700
            Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-15 18:49 -1000
              Re: tethered Forth Brad Eckert <hwfwguy@gmail.com> - 2013-09-16 11:58 -0700
    Re: tethered Forth hughaguilar96@yahoo.com - 2013-09-10 20:47 -0700
  Re: tethered Forth bob.nash1@gmail.com - 2013-09-10 17:27 -0700
  Re: tethered Forth stephenXXX@mpeforth.com (Stephen Pelc) - 2013-09-11 12:54 +0000
    Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-14 15:53 -0700
      Re: tethered Forth stephenXXX@mpeforth.com (Stephen Pelc) - 2013-09-15 17:14 +0000
        Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-15 12:48 -0700
          Re: tethered Forth Gary Bergstrom <forthprgrmr@gmail.com> - 2013-09-17 13:46 -0700
            Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-17 18:55 -0700
              Re: tethered Forth "Elizabeth D. Rather" <erather@forth.com> - 2013-09-17 15:51 -1000
              Re: tethered Forth stephenXXX@mpeforth.com (Stephen Pelc) - 2013-09-18 11:19 +0000
                Re: tethered Forth Matthias Koch <matthias.koch@hot.uni-hannover.de> - 2013-09-18 15:46 +0200
                Re: tethered Forth Paul Rubin <no.email@nospam.invalid> - 2013-09-18 08:43 -0700
              Re: tethered Forth Brad Eckert <hwfwguy@gmail.com> - 2013-09-18 09:10 -0700
              Re: tethered Forth rickman <gnuarm@gmail.com> - 2013-09-18 20:20 -0400

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