[Coco] 1 or 2 meg upgrade

[Gene Heskett]

On Friday 21 November 2014 22:43:56 Luis Antoniosi (CoCoDemus) did opine
And Gene did reply:
> But nowadays SRAMs like Triad does not need refresh :)
> 
> Luis Felipe Antoniosi

I had neglected to make note of that little detail.  And yes, it would 
simply the heck out of a 2 meg design to not have to supply that refresh.
 
> On Fri, Nov 21, 2014 at 10:27 PM, Gene Heskett <gheskett at wdtv.com> 
wrote:
> > On Friday 21 November 2014 15:43:31 Nick Marentes did opine
> > 
> > And Gene did reply:
> > > On 22/11/2014 6:35 AM, Josh Harper via Coco wrote:
> > > >   hi guys
> > > > 
> > > > I was just wondering how hard it would be to copy the 1 or 2 meg
> > > > memory upgrade boards from disto   as id love to have one of
> > > > these myself thanks
> > > 
> > > Would be nice to see Cloud9 release a 1/2Mb version of the triad.
> > > 
> > > Nick
> > 
> > The Triad is a 1/2 meg board, easy.  But to go to 2 megs you'll need
> > to design a circuit that will add 2 more addressing lines to drive
> > the memory mapping of the additional memory in 8k blocks.  One could
> > carry that to its logical conclusion at 8 megs, which has been done
> > but while it was described in the Rainbow, was not to my knowledge
> > ever a commercially offered product.  One of the disto complexities
> > was also the widening of the refresh counter, needed to deal with
> > the square architecture of 99% of the memory sticks out there.  For
> > 8 megs, the addressing IIRC expands to a full 24 bits, needing a 12
> > bit refresh driver, and thats 4 bits wider than the coco's built in
> > dram refresh counter.
> > 
> > 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>
> > US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS
> > 
> > --
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> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco


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>
US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS