[Coco] DMA access for cartridges?

[John W. Linville]

On Thu, May 07, 2015 at 09:52:58AM +0300, John Berry wrote:
> Is it possible for a CoCo cartridge to directly access system memory?
> 
> Like, could you put a custom blitter chip or other hardware on a cartridge, for instance, like was done on some Nintendo carts?
> 
> Brainstorming fictional back story for a retro-ish game project, so practicality is not so import as possibility, but I'm wondering if it even is that.

Yes, I am sure it is possible.  A few years back someone even put a
Propeller CPU on a cartridge and could run the CoCo hardware through
the cartridge slot:

	http://www.coco3.com/community/2011/06/prococo-cart-a-propeller-based-tandyradio-shack-color-computer-2-cartridge/

Unfortunately, the original project page seems to have vanished. :-(

Anyway, some judicious use of HALT should keep the 6809 in check...?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.