[Coco] DMA access for cartridges?

[John W. Linville]

The CART line is routed through one of the PIAs (or the GIME) and
can generate an FIRQ signal on the CoCo1/2 and either IRQ or FIRQ on
the CoCo3.

On Thu, May 07, 2015 at 04:54:28AM -0400, Kip Koon wrote:
> Hi John,
> The only 2 signals from the 68B09E/63C09E that are not connected to the CoCo Slot Expansion bus are the IRQ and FIRQ signals.  All other signals from the cpu are present, so if you can implement DMA without those two interrupt signals, then I would say go for it.  Otherwise some special interface is needed to utilize those 2 interrupt signals.
> 
> Kip Koon
> computerdoc at sc.rr.com
> http://www.cocopedia.com/wiki/index.php/Kip_Koon
> 
> 
> > -----Original Message-----
> > From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of John Berry
> > Sent: Thursday, May 07, 2015 2:53 AM
> > To: coco at maltedmedia.com
> > Subject: [Coco] DMA access for cartridges?
> > 
> > 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.
> > 
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> 
> 
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-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.