Re: [LCtalk] Forth

[Matthijs van Duin]

On Fri, Feb 25, 2005 at 04:38:13PM -0000, Dave Black wrote:
> I was intrigued to hear that there is a Forth compiler hiding in my 
> LAN boxes. How do I get to it and what version of Forth are you using. 
> I keep finding hidden depths in this device which are not referred to in any 
> manual!! Is there a complete, concise CD or printed reference that would 
> allow code writers to really get to grips with the depths of these great 
> devices?

It contains a fairly complete 32-bit ANSI Forth system.  It is accessed 
by connecting to the LanBox serially (USB for LCX) using a terminal, and 
then type the command:  *b7#

When you press enter, it should give the "ok" prompt of Forth.  The same 
command (as a Forth word) will put the LanBox back into its usual mode 
so it can be used with LCedit+.

The Forth system in the LCX is complete with assembler, disassembler, a 
simple debugger, and built-in help system.  The LCM and LCE omit (due to 
size constrains) the help system, but I think is otherwise complete.

A full dump of the help:  http://www.xs4all.nl/~cdsmss/lcxfullhelp.txt

It's also useful to know there are two VALUEs which serve as hooks to 
get your own stuff done every tick:  'PreMixTick  which contains an xt 
which will be invoked after all I/O is done and right before the 
sequence-mix phase.  And  'PostMixTick  contains an xt which is invoked 
right after the sequence-mix but before the post-processing and DMX out.

A simple example would be:

   : my-postmix ( -- )
       MixerOut 1 + C@   MixerOut 2 + C@   MAX   MixerOut 3 + C!
   ;

   ' my-postmix  TO 'PostMixTick

Which would cause channel 3 of the mixer to always be the maximum of 
channels 1 and 2 of the mixer.  You could type this into Forth, use *b7# 
to go back to normal mode, connect with LCedit+ and see the results. 
(or in case of an LCX, you can connect with LCedit via TCP while working 
in Forth via USB at the same time)

Other than the help-dump given above, there isn't really any docs on how 
the firmware works and what things you can tinker (though the short 
answer on that is of course: anything, if you have the time :-).  If you 
have any specific interests, just let me know and I'll dig up the 
relevant info and/or give examples.

Regards

--
Matthijs van Duin  --  May the Forth be with you!