Re: Mockingboard output through IIgs internal speaker?

["Charlie" <charlied@NOSPAMbboard.com>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
20031215142840.08176.00000965@mb-m16.aol.com">news:20031215142840.08176.00000965@mb-m16.aol.com...
> Charlie wrote:
>
> >"Roger Johnstone" <roger@ihug.invalid> wrote in message
> >20031215193734463+1300@news.inv.ihug.co.nz">news:20031215193734463+1300@news.inv.ihug.co.nz...
> >> In <bri3lp01oso@enews1.newsguy.com> Charlie wrote:
> >> >
> >> > I've always wondered why the "monochrome" display setting only worked
> >> > for Double HiRes when using an RGB monitor.
> >> >
> >> > Charlie
> >>
> >> Because double hi-res really has two modes: 560 pixels per line in
> >> monochrome and 140 pixels per line in colour. The older computers had no
> >> way of telling which mode you wanted, so the IIe composite colour
> >> monitor has a switch on the front to turn off colour! The IIgs replaces
> >> that with a softswitch. Some IIgs-aware programs which use DHR graphics
> >> will automatically change the setting themselves e.g. IIRC PublishIt!
> >> uses DHR and will switch a IIgs to monochrome while it's running.
> >
> >Thanks for the information.  I had always thought that DHR graphics had only
> >one mode (140 pixel color) and that the composite color monitor switch just
> >turned off the color burst signal.
>
> The switch on the monitor _does_ simply kill the color decoding.
>
> For any 8-bit Apple (non-IIgs) with DHR, the only difference between
> 140 16-color pixels and 560 monochrome pixels is how the monitor
> interprets the video signal.

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?

> If the 8-bit Apples could disable the color
> burst for graphics modes, then they could control that interpretation.

> The colors on a composite monitor result from chroma decoding of
> four monochrome pixels, and are sometimes known as artifact colors.
> (The design of the Apple II graphics system is based on artifact
> colors.)

This I understand.  In fact I did a hardware hack on my old Apple II+ years ago
that allowed me to kill the color burst part of the signal (by accessing a
softswitch) sent to the monitor or TV.

Charlie