Dual-stack (Forth) processors

Martin Euredjian wrote:
> 
> Davka wrote:
> 
> > Is there a community that is actively involved in discussing and/or
> > developing FPGA-based Forth chips, or more generally, stack
> > machines?
> 
> I've thought about this in terms of internal use.  As much as I like FORTH
> (used it extensively in the 80's and early 90's) the reality seems to be
> that C is the way to go.
> 
> It's a matter of the business equation more than a technical
> rationalization.  FORTH is very cryptic for non-FORTH programmers and
> finding skilled FORTH programmers is not as easy as C programmers.  And,
> while productivity with FORTH can be substantially greater than with C or
> Assembly, you are, eventually, forced to contend with code maintenance,
> reuse and changes in design teams (Oh, no! Our only FORTH guy left!).

You had to go and say that, didn't you!  This is being posted to the
Forth newsgroup and you will hear a few comments about this...  ;)

All that I will say is that I was quite happy coding in Pascal for a
long time.  I switched to C when Pascal compilers were not already
available at a new job.  And I must say that it was a lot harder to
write a working program for a newbie.  

-- 

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

"Davka" <mygarbagepail@hotmail.com> wrote in message news:<T%XXb.70$pM3.121810@news.uswest.net>...
> I want to bring my knowledge about Forth processors up to date, so I'm
> posting some questions.
> 
> Who is currently selling Forth processors?
> 
> What happened to forthchip.com?
> 
> Is there a community that is actively involved in discussing and/or
> developing FPGA-based Forth chips, or more generally, stack
> machines?
> 
> Has anyone done any substantial DSP work in Forth?  Are there libraries
> of code available?

Hi
 I have written a target compiler for Forth to run on the ADSP218x
parts( analog devices ). It is not intented to be used to write
the lowest level of DSP functions, like FFT, IIR or FIR but is intended
to work in parallel with this code written in assembly. As a forth,
I benched it compared to a Novix NC4000. With a 2181 running at 33Mhz,
it executed Forth code at about the rate of a 10Mhz NC4000. That isn't
to bad at all. The code is available on the FIG site someplace.
Dr Ting has also written a full eForth for the same processor. It
is on the CDROM that he sells through Offette Press. I don't know
how it compares to mine. But it does come with an interpreter
and mine is just a target compiler so you'd need to write your
own interpreter and create your own dictionary structure ( you
might look at Chuck Moore's CMForth for a good example of a simple
dictionary/interpreter ).
Later
Dwight

> 
> How about hardware Forth implementations that include dedicated DSP
> hardware?
> 
> Thanks in advance!

Rick,

True, but it works in the window you have in focus.  A previous poster summarized
why I prefer top posting as well.  I can get through tons of posts jsut clicking
in the tree view if they are top posted (no key strokes, so I can do it while
drinking my coffee).  Bottom posted ones require a click in the preview followed
by a keystroke or scroll to get to the bottom.. a two handed operation that is
slower.  Thanks, I'll stick to my top posting

rickman wrote:

> MaI don't know diddly about Outlook, but in most windows programs you can
> go to the bottom of any display by using <ctrl>+<end>.  I belive Jerry
> said that in one of his posts.
>
> --
>
> Rick "rickman" Collins
>
> rick.collins@XYarius.com
> Ignore the reply address. To email me use the above address with the XY
> removed.
>
> Arius - A Signal Processing Solutions Company
> Specializing in DSP and FPGA design      URL http://www.arius.com
> 4 King Ave                               301-682-7772 Voice
> Frederick, MD 21701-3110                 301-682-7666 FAX

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930     Fax 401/884-7950
email ray@andraka.com
http://www.andraka.com

 "They that give up essential liberty to obtain a little
  temporary safety deserve neither liberty nor safety."
                                          -Benjamin Franklin, 1759

rickman wrote:

> > It's a matter of the business equation more than a technical
> > rationalization.  FORTH is very cryptic for non-FORTH programmers and
> > finding skilled FORTH programmers is not as easy as C programmers.  And,
> > while productivity with FORTH can be substantially greater than with C
or
> > Assembly, you are, eventually, forced to contend with code maintenance,
> > reuse and changes in design teams (Oh, no! Our only FORTH guy left!).
>
> You had to go and say that, didn't you!  This is being posted to the
> Forth newsgroup and you will hear a few comments about this...  ;)

I realize that.  No flames please.  I have two decades of Forth experience.
I'm from the days when you built your own computer from chips, wrote a
monitor, got Forth in there, wrote your own editor and then developed your
apps.  I enjoy and love Forth.  I truly do.  I also love a language called
APL.  I think it should rule the World.

Hoewever, when all the smoke and bullshit clears out, you have to run a
business, hire people, survive design team changes, hire consultants,
maintain code, etc. and the "business equation" I refer to can take
precedence.  C is pretty hard to avoid.  I have a current project that I did
in Assembler out of being a snob and not a day goes by that I don't wish I
had done it in C.  We'll have to re-write it eventually, I already know
that.

I also draw from the experience of a good friend who started a biotech
company about fifteen years ago with a product done entirely in Forth.  It
worked great.  He developed it on his own.  Made tons of money.  And then,
he got stuck with it.  He couldn't find decent Forth programmers to remove
himself from that position.  Anyone can write programs in Forth.  Not
everyone can write efficient, well engineered programs tough.  And, not
everyone can walk-up to hundreds of screens of source code and figure it out
without lots of coaching.  He eventually hired me to convert the whole thing
to C.  After that he could hire just about anyone to support and expand the
product.

The only reason I could see to do a Forth machine in an FPGA is that you
might have valuable Forth code that needs to run 100x faster than the
microprocessor curretly hosting it.  So, you do a 6502 (or whatever) on
steroids or a true Forth machine in a fast FPGA and solve your problem.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian

To send private email:
0_0_0_0_@pacbell.net
where
"0_0_0_0_"  =  "martineu"

On Fri, 20 Feb 2004 09:32:49 GMT, "Martin Euredjian"
<0_0_0_0_@pacbell.net> wrote:

>I also draw from the experience of a good friend who started a biotech
>company about fifteen years ago with a product done entirely in Forth.  It
>worked great.  He developed it on his own.  Made tons of money.  And then,
>he got stuck with it.
...
>And, not
>everyone can walk-up to hundreds of screens of source code and figure it out
>without lots of coaching.
...
>The only reason I could see to do a Forth machine in an FPGA is that you
>might have valuable Forth code that needs to run 100x faster than the
>microprocessor curretly hosting it.

What a lot of interesting points! The first paragraph is IMHO about
the cost of converting (competent) programmers to Forth. MPE almost
never hires Forth programmers as permanent staff. In general, learning
the business takes much longer than learning a new programming
language.

The second paragraph illustrates that learning two new things at
the same time is vastly more difficult than learning one. Screens
so often trigger "corporate immune syndrome" that we gave them
up long ago regardless of their technical merit. The quality of
the code is a management issue, not a technical issue.

The third paragraph illustrates what I consider to be a fallacy
these days. Forgive me if I have drawn a wrong inference. With
modern optimising Forth compilers such as MPE's VFX, code quality
for performance is as good as the ouput of compilers for any
other language. The limiting factor is then to find hardware
(with the right price/performance ratio) to run the application.

Stephen
--
Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads

In article <pan.2004.02.20.00.04.34.373349@gurney.reilly.home>,
Andrew Reilly  <andrew@gurney.reilly.home> wrote:
<SNIP>
>
>Well if you were happy with 64k, then the segmentation wasn't a problem:
>you could be in "tiny" mode all the time (which is how the CP/M converters
>worked, I believe.)  The x86 had some more instructions and better
>addressing modes than either the 8085 or Z80.  Probably not necessarily
>nicer than the 6809 though (but I only read about the latter: never got to
>actually play with one.)

I can. I've recently been involved in getting two Forths working on
6809 boards (for fun and education). Where the 6502 is the nicest
true 8 bit processor, the 6809 is the nicest 8/16 hybrid processor.
Its reputation is well deserved, it really is a brilliant design
and a joy to program for.
(If you ever manage find the description of the 8086 by its designer
Morse. It is actually not such a bad design.)

Last saturday I gave a talk for the Dutch fig chapter about assembly
programming in Forth. I shaved off 16 states from the 44 states inner
cycle of UM/MOD (Camelforth version). I would be interested if an
optimising compiler could get UM/MOD down to that ...

We (=Dutch Fig chapter) got those boards for free. (Still plenty left
to dole out.) See also http:/home.hccnet.nl/p.c.wiegmans/6809werkgroup
In principle this is a Dutch page, however all programs and most
downloads are in English.

Coming up next are those 68020 VME crates. Studying the addressing
modes (18 in total!) gives the same feeling as the 80386.
It is going overboard with indirect base register with scaled offset
register plus internal and outside offset and such (I don't claim
to get that one right but you get the drift.)

>Idle curiosity: why pick the 8085 over the Z80, in that time frame?

Built in serial port. I like the Z80 but its serial companion chip was
a great pain.

>
>Cheers,
>
>--
>Andrew
>


--
-- 
Albert van der Horst,Oranjestr 8,3511 RA UTRECHT,THE NETHERLANDS
        One man-hour to invent,
                One man-week to implement,
                        One lawyer-year to patent.

In article <nvdZb.27841$A72.20220@newssvr25.news.prodigy.com>,
Martin Euredjian <0_0_0_0_@pacbell.net> wrote:
>Jon Harris wrote:
>
>> Ctrl-End.  I guess it's 2 key strokes, and you still have to click within
>> the message, though Tab will also move the focus from the tree view to the
>> preview pane.
>
>If focus is in the preview pane just "End" will get you to the bottom.
>
>Sorry for the off-topic nature of this. I scan-through and read hundreds of
>emails and newsgroup posts per day and just a few extra keystrokes can be a
>pain in the you-know-what.

Bottom posting is bad. It lures Windows Lusers into not snipping anything.
If a post doesn't fit on a screen (this one does) you are supposed to
warn [LONG] in the subject line.
What is a pain to you is not bottom posting but the people that are
in the habit of not snipping.

<SNIP>
-- 
Albert van der Horst,Oranjestr 8,3511 RA UTRECHT,THE NETHERLANDS
        One man-hour to invent,
                One man-week to implement,
                        One lawyer-year to patent.

In comp.arch rickman <spamgoeshere4@yahoo.com> wrote:
> 
> The older Xilinx parts have small LUT based rams that have true 3 port
> memory.  But how they implemented it shows that you can always make a 3
> port memory from a pair of two port memories.  They tied the two write
> ports together so that the two RAMs always were written with the same

This would also work with any ram arhicture, no?

> data.  But the read ports were kept separate allowing any two words to
> be read at the same time.  
> 

But there are other things you can do - you can convert the lack of 
ports into a scheduling restriction where you get a pipeline bubble
if one of the source operands is not being forwarded from a previous
instruction. 

The other option is doubling clock cycle and having two pipelines that
can pair instructions whenever there are enough ports (including forwards) - 
things like the right code mix and immediate argumnets (plus some help
from scheduling) can make for a very nice result. 

There are others.

-- 
	Sander

+++ Out of cheese error +++

Albert van der Horst wrote:

> Where the 6502 is the nicest
> true 8 bit processor,

Rockwell's R65F11 was a nice 6502 + Forth chip.  I still have a dozen or so
wire-wrapped R65F11 boards in the garage somewhere.  I built them back
around '85 for a light-industrial robot arm I designed as well.  One
processor per axis.  Hardware (as in wire-wrapped 'HC parts) PWM.  An
additional processor for supervision and yet another to communicate with a
PC/programming console.  That was a fun project.

Today you could probably stuff all of into a single FPGA.


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian

To send private email:
0_0_0_0_@pacbell.net
where
"0_0_0_0_"  =  "martineu"

In comp.arch, "Martin Euredjian" <0_0_0_0_@pacbell.net> wrote:

>Jon Harris wrote:
>
>> Ctrl-End.  I guess it's 2 key strokes, and you still have to click within
>> the message, though Tab will also move the focus from the tree view to the
>> preview pane.
>
>If focus is in the preview pane just "End" will get you to the bottom.
>
>Sorry for the off-topic nature of this. I scan-through and read hundreds of
>emails and newsgroup posts per day and just a few extra keystrokes can be a
>pain in the you-know-what.

Well, Outlook Express is crap as a newsreader. Most newsreaders have a
"single-read key" key that pages through a message, then skips to the
next unread one at the end. This is why you don't see users of other
newsreaders complain so much about skipping some text. Trimming the
quotes is a good thing, nevertheless.

Outlook Express is crap as a newsreader. I could go on and on about
it, but I bet you didn't know.