[Coco] Kicking the Z-80 butts...

[John W. Linville]

On Tue, Apr 28, 2015 at 02:20:41PM -0500, Zippster wrote:
> Well, it is late ‘70s technology.  Earlier that decade the first microprocessors were introduced.
> I guess the 6847’s major weak point is probably the terribly limited 32 column text display.
> Other VDGs of the time were pretty low-resolution as well.  But you have to remember there 
> wasn’t much resolution available on the display devices either, even if you would have had the silicon for it.

IMHO, the only real problem with the 6847 is the available colors.
Even the individual colors aren't terrible, but the inflexible
combinations seem to have been chosen by a colorblind sadist...
Only being able to have green or white (depending on color set chosen)
for the background color is also...painful.

The 32-character line width in text mode isn't great, but it is a lot
better than the VIC-20's 22×23 text layout.  And at least with a power
of 2 for the line width, you don't have to do the arithmetic gymnastics
required by the Apple II when computing a character's offset in memory!

Overall the resolutions for the 6847 aren't too bad given the time
it was released.  The fact that it was "off the shelf" should have
made it very attractive for a variety of uses.  In fact, I know of at
least one industrial "over computer" that shows-up on eBay from time
to time that used it.  If the color palette had been more flexible
then I'll bet it would have been much more highly regarded...


> Video is just a massive amount of data once you start to move past 300x200 or so and just a few colors.
> Even the 6809 will start to choke pretty quickly heading in that direction.

Which is why the coco3 probably should have had a blitter...

> Although it is a pretty incredible 8-bit CPU with an interesting story behind it.
> It should have been more popular.

How popular were Defender and Robotron? :-)

> 
> - Ed
> 
> 
> > On Apr 28, 2015, at 1:28 PM, Gustavo Ranaur Schoenaker <ranaur at ranaur.net> wrote:
> > 
> > Really amazing.
> > 
> > The more I know the 6809 the more I think the problem with the chip was no
> > t the processos, but the 6847. Maybe it was the reason Tandy made the GIME
> > chip on CoCo 3. Video is really the upper limit of the plataform. At those
> > times the video chip make a huge difference.
> > 
> > Nice job Luis!
> > 
> 
> 
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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.