Re: Let's pay a developer to make a VGA output card

["js@cimmeri.com" <js@cimmeri.com>]

Alex Freed wrote:
> S-video is only different from composit video in one respect - the color
> information comes on a different wire than the luminance. The way video
> is generated in apple 2, they are inherently mixed. So it doesn't matter
> much if you try to separate them at the computer side rather than inside
> the TV. A modern TV will likely do a better job with a comb filter.

   The Apple II/+ was designed for composite or RF, and likely would
best be utilized there forever.   But, looking at the schematics for
the Apple IIgs, I found that they used an MC1377 Color Television to
Pal/NTSC encoder chip after the VGC.    The VGC supplies RGB+Comp/Syn
to the RGB connector directly, and also supplies the MC1377 for
eventual composite video output.

   Looking at the specs for the MC1377, there is revealed some circuit
mods to allow this same chip provide S-Video!   The specs also discuss
the comb filter idea mentioned by Alex above.  But, the s-video sounds
like a very interesting prospect.    S-Video on my vid equipment is
significantly better than composite.   Does anyone have a feel if it
would be adequate for 80col display?

     My aim here with all the VGA stuff is not to get VGA resolution,
but rather, to find a monitor that will work with the GS down the road,
after these 1986-1988 RGB monitors die.   Prospects look dim so far.
Hooking up the IIGS to even my composite input LCD TV, produces
horrible results.   CRTs seem best.   CRTs made now use S-Video.

~ J