[Coco] Bubble Memory

[Gene Heskett]

On Tuesday 15 August 2017 14:01:07 Bruce W. Calkins wrote:

> The CoCo 3s GIME can map any 8k block from up to 2 megs of memory
> anywhere in the 6809s 64k address space.  The CoCo 1 & 2s SAM was
> pretty much limited to 32k blocks upper and lower.  OS-9 level 1,
> Release 2 was a little better than Color Basics ability to handle
> that, but without better hardware, that 32k limit does strangle things
> a bit.
>
> I have the PBJ 256k Banker and OS-9 needs a patch just to boot. To
> date no one seems to have come up with the patch for NitrOS9.
>
> Bruce W.
>
I think that would probably need some hardware hacking in the pbj to 
allow it to address translate on 8k boundaries like the gime uses. If 
that was done, then its possible the memory chips on the pbj could be 
swapped out to make a 2 meg kit out of it without too much more hacking.  
I wonder how many 256k pbj kits were sold back in the day. Does anyone 
have a better idea than my SWAG of 20?

> On 08/15/2017 11:12 AM, Brett Gordon wrote:
> > that limit is done and gone no?  Tormod's spinx card now can map
> > near 64k in and out.  I assume it would be trivial now-a-days to add
> > more granular banking if one desired, or a crap ton of banked
> > memory.
> >
> > Actually putting any such scheme to use software-wise would be
> > probably more work than the hardware involved.
> >
> > On Aug 15, 2017 8:31 AM, "Bruce W. Calkins"
> > <brucewcalkins at charter.net>
> >
> > wrote:
> >> One of the limits to the CoCo 1 & 2 memory expansion was the
> >> inability to
> >
> > shift small-to-medium sized blocks in and out of the memory map. 
> > Basically it was limited to 32k mapping blocks.  This applied to the
> > PBJ 128k & 256k expansions too.  That said; RAM Disks really did
> > speed up many processes.
> >
> >> Bruce W.


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>