[Coco] Re: again: CoCo RGB to VGA conversion

[jdaggett at gate.net]

VGA specs are th is

2 lines front porch
2 lines sync
25 lines back porch 
8 lines top border
8 lines bottom border

480 lines display 

total 525

sound familiar?

james

On 23 Aug 2004 at 21:09, Mark Marlette wrote:

Date sent:      	Mon, 23 Aug 2004 21:09:34 -0500
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
From:           	Mark Marlette <mmarlett at isd.net>
Subject:        	Re: [Coco] Re: again: CoCo RGB to VGA 
conversion
Send reply to:  	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
	<mailto:coco-
request at maltedmedia.com?subject=unsubscribe>
	<mailto:coco-
request at maltedmedia.com?subject=subscribe>

> At 8/24/2004 01:45 AM +0000, you wrote:
> 
> I would not add the composite mode into it......
> 
> Garbage in....garbage out. Keep cost down, RGB only.
> 
> I would have to review my TV course text book but you have vertical
> blanking which accounts for x number of lines. Heck that was 20 years
> ago.......
> 
> My approach would have a line counter so that you could double or run
> original size vertically.
> 
> Someone here will probably beat me to this project. Too many other
> CoCo projects in front of this one. Hardware talent all around. lets
> get some more software development going!
> 
> Can someone make more hours in a day? I'll buy a couple.... :)
> 
> Mark
> Cloud-9
> 
> 
> 
> > > > It's hard for a converter to scale up a line to a fraction of a
> > > > line, such as 1.5 lines (without some significant gray-level
> > > > anti-aliasing). Let's see, the VGA has 480 lines.  Straight
> > > > Coco3 has 384, or 80%, so you have 10% of the total screen
> > > > height blank at top and bottom.  Not too bad. RSBASIC and maybe
> > > > even OS-9 can be poked up to 200 high, or 400 out of 480. Some
> > > > BASIC hackers claim to have hit 225, or 450 out of 480.
> >
> >Where does the 384 come from? Is that vertical padding? With 225
> >lines to work with, that's 159 extra lines. Right? So the ideal thing
> >for this conversion hardware to do, would be to snip out those 159
> >blank scan lines, and mutliply the usable 225 by a nice integer,
> >namely 2. That would produce 450 scan lines, with a margin of 30
> >lines to fit within a 480 line screen. Piece of cake! :-)
> >
> >Oh, and a switch to choose either the analog RGB signal or the
> >composite signal would be nice. That way, users could have the best
> >of both worlds, RGB for most apps, and composite for software which
> >uses artifacting.
> >
> >David
> >
> >
> >--
> >Coco mailing list
> >Coco at maltedmedia.com
> >http://five.pairlist.net/mailman/listinfo/coco
> 
> 
> 
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco