Re: Alternatives to an applecolor RGB?

[Daniel Kruszyna <dan@krue.net>]

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.

-- Daniel