Re: Mockingboard output through IIgs internal speaker?

[Jeff Blakeney <CUTjblakeney@sympatico.ca>]

On Mon, 15 Dec 2003 16:05:59 -0500, "Charlie"
<charlied@NOSPAMbboard.com> wrote:

>Well, now I have to admit I'm pretty confused.  My original post was meant to
>be about the Apple IIgs monochrome display setting only working with DHR
>graphics when using an RGB monitor.  I understood Roger Johnstone's answer to
>mean that on an Apple IIgs there is actually two different DHR modes.  One that
>is used to generate the signal for a composite monitor and a second for an RGB
>monitor.
>
>If this is not true then I still don't understand why it only works for DHR
>graphics on an Apple IIgs with an RGB monitor.  Why not LoRes, HiRes, SHR as
>well?

It was sort of mentioned but I guess it can easily be overlooked.
Having the monochrome control panel setting only give you monochrome
with DHR graphics when using an RGB monitor is so that you can
actually use programs like PublishIt! and the Star Trek: First Contact
game that use monochrome DHR graphics.  If you couldn't force the DHR
screen into monochrome then the display would be practically
unreadable for those programs because each set of four monochrome
pixels would be interpreted and displayed as a single colour pixel.
If the control panel setting didn't work the way it did, the only way
you could use those programs would be to hook up a composite monitor
and use those programs on it.

The other modes never get switched into monochrome mode on an RGB
monitor because there is no need.  You will always be able to read the
screen with colour turned on so the monochrome control panel setting
only affects the other modes for the composite video output where you
might not be able to read some of those displays using a composite
monitor due to colour bleeding.

That said I'll confuse the issue further by mentioning the fact that
some people did do monochrome hi-res graphics that won't display
properly if the colour burst is still on.  In fact, from at least the
Apple II+ on up, it has been possible to do 560x192 monochrome
graphics (with limitations but we're used to those :-) using only the
hi-res screen.  By plotting a single dot on the screen it is only
using half of that pixel on screen and by setting the high bit of the
byte that that pixel is sitting in, you can shift that one dot to the
other half of the pixel.  I remember typing in a demo program from a
magazine that demonstrated this method many years ago but have never
had the desire to try to put it into use.  :-)

-- 
 Jeff Blakeney - Dean of the Apple II University in the
                 Apple II Community on Syndicomm.com
 CUT the obvious from my address if you want to e-mail me