[Coco] [Color Computer] 1M simms in Cloud9 SIMM upgrade kit

Paul T. Barton idezilla at yahoo.com
Thu Jun 30 16:26:36 EDT 2005


--- Mike Pepe <lamune at doki-doki.net> wrote:

> Paul, this is a hidden refresh cycle I take it.
> Or is it a CAS before RAS refresh?

CAS before RAS, not hidden.
Upon reading about it,
I found out that the DRAM has it's own
internal stuff to take care of this
type of refresh.

> Funny, I thought you had to run through an
> entire cycle of 512 addresses 
>   during that. This is really interesting.

No, not needed, the DRAM takes care of that.
I'm surprised no one else uses it, it's free.
All you have to do is guarantee CAS goes
active before RAS and not by much, either!
When they terminate both can go inactive
together, no worries.

> Paul T. Barton wrote:
> > Mike,
> > 
> > Yes. During HSync or VSync the ras/cas pairs
> > get swapped. No video there and only during
> > non-e timing (video accesses). I documented
> > this with a TEK 'scope on the old site.
> > http://home.wwdb.org/irgroup/scope.html
> > 
> > Paul

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