Re: tethered Forth

Newsgroups	comp.lang.forth
Date	2013-09-10 20:47 -0700
References	<7xli38v3gj.fsf@ruckus.brouhaha.com> <laqdnac8I6t7C7bPnZ2dnUVZ_q2XnZ2d@supernews.com>
Message-ID	<e0c1ccbb-e855-4c4b-a14f-59d73353b330@googlegroups.com> (permalink)
Subject	Re: tethered Forth
From	hughaguilar96@yahoo.com

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On Saturday, September 7, 2013 2:13:10 PM UTC-7, Andrew Haley wrote:
> Paul Rubin <no.email@nospam.invalid> wrote:
> > Is idt normal when using one, to develop against the target from
> > beginning to end,
> 
> Yes.  IME there really isn't much point developing on the host.
> 
> The traditional reason for developing on the host was that the
> environment on the target was crap.  Once you make it not crap -- by
> using Forth -- all reasons for developing on the host evaporate.

MFX developed on the host. It wasn't that the target environment was "crap" --- the target processor just didn't exist yet. Throughout most of the development of MFX, the MiniForth itself was under development. The definition of the MiniForth changed on an almost daily basis. Both MFX and the motion-control program were completed using simulation prior to the MiniForth existing as a physical chip.

This is the best way to develop a new processor. I think it is a big mistake to develop a new processor and then afterward develop a compiler for it --- because you don't know what instructions you want until you have the compiler working and discover that your compiler is generating inefficient code with the instructions that you have, and would generate better code with a different instruction set. The processor and the compiler are developed in conjunction so that each can be molded to fit the other.

It is true that developing on the host and uploading entire programs to the target, is not very interactive. With a tethered system, you are uploading portions of code to the target on the fly, and the whole process is interactive, similar to developing on the target itself as in a traditional Forth. That is what I've heard anyway, as I've never used a tethered system.

After I left Testra, they used MFX to write a traditional Forth that ran on the target. Most likely, the just didn't know how to write a tethered system. I could do it, but I was gone by that time. Anyway, the MiniForth is a pretty big processor and it can support a traditional Forth easily, so a tethered system wasn't really needed. I think that tethered systems would mostly be useful for processors that are too small to support both a Forth compiler and an application program.

The problem with a traditional Forth on a processor such as the MiniForth, is that it can only be used to develop Forth code, but not assembly-language code. This is because the processor is Harvard architecture, with the Forth code and the data in one memory, and the machine-code in another memory --- the latter being memory that can't be written to by the processor itself. Because of this, Testra must still be using my MFX when they need to write assembly-language code --- it is just not possible to do that with a Forth running on the MiniForth itself.

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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