Re: IIgs video modes...

[dempson@actrix.gen.nz (David Empson)]

Linards Ticmanis <ticmanis@gmx.de> wrote:

> Michael J. Mahon wrote:
> 
> > The answer is in the schematic--the NTSC color signal is created
> > not by the multiple-of-3.58MHz pulse scheme that is the Apple II
> > standard, but by a chrominance modulator driven by the RGB signals.
> > Therefore, its color rendition is not dependent on its pixel rate.
> 
> Does this apply only to SHR modes, or also to IIe compatible modes?

Probably all modes.

The IIgs RGB output emulates the colour behaviour of 8-bit Apple II
video modes, e.g. alternating green/violet pixels in HGR mode, with an
odd coloured pixel every 14th (yellow or brown).

The NTSC composite output can generate a proper colour burst derived
from the emulated colour, producing the right effect on NTSC, but with
proper colour encoding rather than a simulated colour burst and having
to rely on timing tricks.

-- 
David Empson
dempson@actrix.gen.nz