[Coco] Suggested RAM area for ML program to be used from BASIC?

[Arthur Flexser]

There's some space available above the end of Super Extended Basic that you
could use for the CoCo 3 version (which would also work for the CoCo 1/2 if you
copied ROM to RAM first ONLY for the earlier machines--don't do that for the
CoCo 3 or you'll knock out Super Extended Basic).  I don't have my reference
materials handy, but if your program was at $FC00 or thereabouts, that'd
probably be high enough to clear the top of Super Ext. Basic.  Perhaps someone
here could chime in with a more precise answer.  There's a character set used by
HPRINT up there somewhere, then above that is garbage you can safely overwrite.

A small correction to my earlier statement about CLEAR:  if your program is at
$7F00, you probably need to use CLEAR 200,&H7EFF--the extra byte, I believe, is
needed only for the CoCo 3.

Art

On Sun, 8 Jun 2008, Fedor Steeman wrote:

> Thank you guys and especially Gene for the fascinating story. I was already
> getting a feeling that all useful memory would be used up in a CoCo3.
> 
> I am not sure yet how big it would become and I need to preserve all of
> BASIC, so using the cassette buffer, although an interesting suggestion,
> wouldn't be it.
> 
> I think I will proceed with the CLEAR statement.
> 
> However, I wonder, if (still) only 32K would be available in Super Extended
> Color Basic, what is all the memory at the bottom of RAM, supposedly 'Unused
> by Basic' used for (0-5FFFF)? Maybe I can have a CoCo1/2 version reside at
> E000-FEFF and a special CoCo3 version somewhere else?
> 
> Cheers,
> Fedor
> 
> 2008/6/8 Arthur Flexser <flexser at fiu.edu>:
> 
> > On Sat, 7 Jun 2008, Frank Pittel wrote:
> >
> > > I don't remember where I got this from but I seem to remember a way
> > > to reserve memory for machine language programs from within a basic
> > > program. Seems like the best way to do it to me.
> > >
> > > Frank
> >
> > You're thinking of the CLEAR statement:  if the ML program is at $7F00, do
> > a
> > CLEAR 200,&H7F00 to protect the program from Basic and reserve the usual
> > 200
> > bytes of string space just below it.  This would generally be in the first
> > line
> > of any Basic program that has to coexist with the ML.
> >
> > Art
> >
> >
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> >
> 
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