Re: My Apple IIGS is back

["Michael J. Mahon" <mjmahon@aol.com>]

limtc wrote:
> Hi,
> 
> I have been doing this experiment ever since I got a ROM 3 Apple IIGS
> without a monitor. What will you see on the LCD TV connected to the GS
> via the yellow video cable? (there is a thread of discussion here).
> 
> The answer is surprising. In text mode, I always see clear nice
> monochrome text, regarding of the setting in control panel. When
> switch to graphics mode (from Lores to Super Hires), it shows the NTSC
> color (blur with color shift).
> 
> You can see the monochrome text here:
> 
> http://retromaccast.ning.com/photo/photo/show?id=1672786%3APhoto%3A17100&context=album&albumId=1672786%3AAlbum%3A15145
> 
> But in graphics mode, it looks like this:
> 
> http://retromaccast.ning.com/photo/photo/show?id=1672786%3APhoto%3A17305&context=album&albumId=1672786%3AAlbum%3A15145
> 
> Which is surprisingly good for graphics, but text is blur. Hard to
> read if it is 80 column text, 40 column is still fine. Whenever text
> mode is turn on, the text returns to clear monochrome text.

NTSC composite color processing generally does not preserve luminnance
information beyond about 3MHz, so 80-column text is usually unreadable.

In monochrome mode, there is more flexibility and your monitor may
make use of extended luminance bandwidth to render 80-column text
well.

> But in ROM 1 GS, it started fine in clear monochrome text, but once
> enter graphics mode, it stays in NTSC color.

This is standard behavior--a monitor cannot switch quickly (within
a frame) from color to monochrome and back.

The Apple II generates a color video signal anytime that graphics
are displayed, even if the screen is "mixed".

-michael

NadaPong: Network game demo for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

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