Hi everyone! I'm in Missouri, without direct access. So I'll be
unusually slow (sorry! sorry!) about reply to emails. This should
only last a couple of weeks.
-Chris
On Wed, 14 Aug 2002, Billy Eno wrote:
> Chris,
>
> This is from a month ago, I think I want to give it a shot.
>
> You say you hit the RSYNC half way through line 262. Then, you draw the
> next interleaved frame, which is also 162 lines. You said you have to play
> with VSYNC, how do you play with it, does it just need to be hit at the same
> time as the RSYNC, to get the display to start over at the top?
>
> And, did you actually get this working on the 2600 at one point, or are you
> talking about some other system?
>
> Billy
>
> > -----Original Message-----
> > From: owner-stella@xxxxxxxxxxx [mailto:owner-stella@xxxxxxxxxxx]On
> > Behalf Of Chris Wilkson
> > Sent: Sunday, June 30, 2002 11:46 PM
> > To: stella@xxxxxxxxxxx
> > Subject: RE: [stella] Higher Resolution through Interlacing
> >
> >
> > On Sun, 30 Jun 2002, Billy Eno wrote:
> >
> > > Interesting background on how TV's actually work. I certainly
> > was unaware.
> > > It would be pretty easy to write a demo to see if it worked (I
> > think), and I
> > > may try. But, if a TV interlaces two succesive Atari 2600 "frames" to
> > > create an image, how would you (or the TV)know if the first frame was an
> > > "odd" (to the TV) or an "even" (to the TV). If the you didn't
> > start with
> > > the correct frame, likely the graphics wouldn't look right.
> >
> > The 2 fields should properly look like this:
> >
> > ******************** xxxxxxxxxx
> > ******************** xxxxxxxxxxxxxxxxxxxx
> > ******************** xxxxxxxxxxxxxxxxxxxx
> > ******************** xxxxxxxxxxxxxxxxxxxx
> > ******************** xxxxxxxxxxxxxxxxxxxx
> > ******************** xxxxxxxxxxxxxxxxxxxx
> > ********** xxxxxxxxxxxxxxxxxxxx
> > field 0 field 1
> >
> > Notice that field 1 starts in midline, just where field 0 left off. And
> > field 0 starts at the beginning of the line, where field 1 left off.
> > If you draw these 2 fields sequentially, you see how the lines get
> > interlaced. Remember that the lines are actually drawn diagonally,
> > because the electron beam moves downward at a constant rate. It's hard
> > to draw in text, but I'll try. Heres a display with 2.5 lines per field,
> > or 5 lines per frame: (again, "*" represents field 0 and "x" represents
> > field 1)
> >
> >
> > * x
> > * x
> > * x
> > x *
> > x *
> > x *
> > * x
> > * x
> > * x
> > x *
> > x *
> > x *
> > * x
> > * x
> > * x
> >
> > -Chris
> >
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