[Coco] clearing memory for other uses

[Jason M]

Yes, exactly, no plans to use anything in basic.

Am i correct in thinking that there is roughly 2k of memory at the top of
the 4th high-res page that is not used for video when in 320x200x16 mode?

I'm thinking of setting up mmu map 0 and map 1 to both have page 4 in the
same slot. That way even when I'm not drawing I can expect things to be in
memory in that high 2k.

BTW, I'm targeting this for a CoCo3 w/ 128K.


On Jan 30, 2016 12:05 AM, "Barry Nelson" <barry.nelson at amobiledevice.com>
wrote:

>  The short answer is you can get rid of the entire rom if you wish. This
> is what OS9 or NitrOS9 do when they load, they do not use the rom at all.
>
> > Robert Gault robert.gault at att.net
> > Fri Jan 29 22:51:46 EST 2016
> >
> > Jason M wrote:
> > > Sorry if this is a double post, I originally posted this morning as a
> > > followup to Robert's question asking if it is possible to disable SECB
> on a
> > > coco3, but it doesn't look like it went through ...
> > >
> > > Along these same lines, what else could be cleared out to make the most
> > > room for game program and data ?
> > >
> > > I came across this nobasic.c program (
> > > http://perso.b2b2c.ca/sarrazip/dev/nobasic.c) which made me start to
> wonder
> > > what else could go ...
> > >
> > > I'm planning to use high res graphics so I know (think) i need those 4
> 8k
> > > pages - and I think I read there are some things in the top end of of
> > > memory that are necessary - is everything else fair game ?
> > >
> > > thanks,
> > > JasonM
> > >
> >
> > Jason,
> >
> > If you are going to write your game and make no use whatsoever of any
> Basic ROM
> > code, you can use ALL of RAM for your game and graphics. While you have
> not been
> > very clear about this, it reads as if you want to use some of the ROM
> code but
> > not all of it. That being the case, you do have the option of running
> the ROM
> > code while in mixed RAM/ROM mode and running your game in all RAM mode.
> >
> > It is simple enough to have a routine in low RAM that switches between
> the two
> > memory modes as needed. You could also make dram at $FE00-$FEFF constant
> and use
> > that for your routine to switch between memory modes as needed.
> >
> > In short, all you need to retain to use Basic routines is some of the
> RAM from
> > $00-$0A00 depending on what ROM code you want to use. You will get better
> > answers to your questions as you become more explicit about what you are
> trying
> > to accomplish. "Make the most room for game program and data" isn't even
> close
> > to being specific enough. :)
> >
> > Robert
>
>
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