Re: Alternatives to an applecolor RGB?

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

Charlie <charlieDOTd@verEYEzon.net> wrote:
> On 10/7/2011 5:04 AM, Daniel Kruszyna wrote:
>> Charlie<charlieDOTd@vereyezon.net>  wrote:
>>>> The problem is that any device that proposes to generate VGA video from an
>>>> Apple II (of any stripe) must also faithfully (instantaneously) render the
>>>> results of rapid video mode switching--a very difficult feat for non-native
>>>> video generation.
>>> 
>>> I'm not sure I see the problem.  To switch video modes you need only "watch"
>>> for accesses to the appropriate soft-switches.  When a soft-switch is
>>> accessed the card switches to the appropriate circuitry, probably faster than
>>> the Apple II.  While "playing around" with the Carte Blanche VGA video I
>>> often have two monitors (one with the native Apple video and the other from
>>> the Carte Blanche) side by side and I see no perceptible difference when
>>> video modes are switched.  The hardest part (for the designer) is knowing
>>> what happens when certain soft-switch combinations are accessed.  The
>>> documentation is a little vague on some modes.
>> 
>> The difficulty arises when soft switches and video ram are changed _while the
>> screen is being drawn_. In this case, the converter must be synchronized to the
>> native video scanner.
>> 
> 
> In the case of the Carte Blanche card the video RAM and soft-switches are
> being used in a very similar way to the native Apple.  Any problem that
> would arise from changes to the video RAM/soft-switches while the screen
> is being drawn should be the same for both.  The Carte Blanche and
> presumably the Second Sight card do not generate the VGA "on the fly" but
> buffer the video RAM and internally mimic the status of the
> soft-switches.  The speed of the card is much faster than the Apple so it
> can easily keep the buffer "up to date".
> As Alex has pointed out, the GS specific modes are not supported "out of
> the box".  Still with limitations (mostly with the number of colors) you
> can have a very sharp (some would say too sharp :-) Finder Desktop.  See
> the picture at this link:
> 
> http://noboot.com/charlie/cbnotesgs1.htm
> 
> Charlie

Are you saying that a SecondSight or Carte Blanche will correctly render an
Apple display in which a "window" of a different video mode (say, hi-res)
is created by synchronous mode switching within a page of a different mode
(say, text)?

That's a pretty tall order...

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon