[Coco] clearing memory for other uses

[Barry Nelson]

 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