[Coco] Fahrfall, an arcade-style game for the CoCo 1/2

[John W. Linville]

On Wed, Jan 11, 2012 at 04:29:41AM +1100, David Roper wrote:
> I'm curious as to what graphics mode you're using, and how you're achieving
> those colours on a CoCo 2?
> 
> I'm from PAL-land, and have never experienced the wonders of a CoCo 2
> generating artifact colours 'natively' (only under emulation)
> 
> What gives, John?

Easy, now!  I plan to cover that in an upcoming blog entry...

But, rest assured that those are "real" colors coming directly from
the 6847 -- I don't know what the PAL CoCos did for conversion, but
I would guess that those should display all the colors reasonably well.

The video mode is Semi-Graphics 12 (SG12), one of the modes that the
CoCo2 does but that the CoCo3 (normally) can't do.  It is enabled
by the combination of the 6847 VDG and the 6883 SAM in the CoCo 1/2
(and the TDP-100 and the Dragon and the other "clones").  One of the
beauties of these modes is that you can have 8 colors + black + the
olive background of the inverse characters all on the screen at the
same time.  The downside is that the individual pixels are wierdly
shaped, and any given pair of pixels either have to be the same color
as each other or one of them has to be black (or they have to be a
piece of a text character).

Anyway, I intend to go into further detail on the blog -- be sure to
add it to your RSS reader! :-)

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