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Re: Apple][VGA - finally available
Mark McDougall wrote:
Michael J. Mahon wrote:
Another method is to eavesdrop on the Apple II peripheral bus and
completely recreate Apple II/IIgs graphics modes using another processor
and frame buffer, from which VGA video is generated. This has the
advantage of extreme versatility, combined with the disadvantage of
extreme versatility. ;-) It invites the invention of graphics modes
with no support on the Apple II platforms. To the degree that is simply
aims to emulate the native Apple II graphics modes, it takes on the
responsibility of a full emulation--ideally even including frame buffer
timing for "mixed mode" displays--which is quite complex and apparently
was never fully done...
I can't agree with your assertion that an "[invitation to invent]
graphics modes with no support on Apple II platforms" is a
"disadvantage" of this approach.
I meant that in the sense that the creation of new graphics modes
unsupported by software is a tantalizing but ultimately useless
effort. I could be fun for the person doing it, though. ;-)
However I do agree that it takes on the responsibility of full
[graphics] emulation.
If it isn't clear ;-), I think that the latter approach--the one
taken by the Second Sight card--is a failed strategy.
I'd say that it's an approach that has yet to be sufficiently implemented.
And I'd say that if it's been this long without sufficient
implementation, then the design complexity is too great.
There is no value in offering modes that are not supported by any
meaningful software base or tools. And the job of fully emulating native
modes is much more subtle than designers first realize.
There is no value to you perhaps, but can you speak for others? However
I whole-heartedly agree that the job is more subtle than it would appear.
I have no problem at all with it being a playground for the developer.
But I cannot regard it as a solution to the very practical problem that
many people have expressed: a simple, affordable way to use a VGA
monitor with their Apple II or IIgs.
Put another way, Woz designed the Apple II to make color on the rather
imperfect analog NTSC monitors of the day, and legions of game designers
designed their graphics for these monitors, since they knew that
practically all of their customers would be using similar monitors to
view them.
Absolutely! And whilst I agree that any solution that cannot offer a
comparable viewing experience is inferior, I don't believe that this
approach necessarily dictates that it will be the case for any derived
solution.
OK. I only note that, for me, any acceptable solution must be capable
of replacing the NTSC color monitor without compromises in graphics
quality or rendition. Looking like a traditional "RGB card" is not
such a solution.
There is a whole spectrum of users, each with their own needs and
expectations, and I don't think anyone can speak for them all. Anything
short of a vintage RGB monitor will not satisfy a purist - likewise some
users are happy to simply play Lode Runner on the Applewin emulator. And
in between we have yourself, Geoff & I.
A vintage RGB card does not satisfy the purist in me!
I want the best of all worlds--great monochrome for text, great analog
RGB for SHR and the occasional non-pictorial graphics, and great NTSC
emulation for most traditional graphics.
The Apple][VGA achieves all this insofar as it applies to 8-bit Apple II
machines. It would be nice to see a similarly successful card for the
Apple IIgs.
Personally, I prefer the bus snooping approach because of the
"(dis)advantage of extreme versatility". Granted, it's more work and
perhaps even impossible to get *exactly* right, but I believe it's very
doable and would produce acceptable results for most users who want a
comparable viewing experience in each video mode, but can't justify the
space or expense of a dedicated Apple II monitor.
If the aim of the "versatility" is simply to allow a perfect recreation
of the existing Apple II graphics, then it is of little use (since the
Apple II already emulates itself perfectly ;-). It seems to me that it
is useful only as a vehicle for experimenting with novel graphics modes
not widely supported by software.
If that appeals to you, more power to you--but I think the vast majority
of those who have expressed themselves on this topic are motivated by a
desire to "cut the cord" to Apple-specific monitors and get their Apple
systems to share modern VGA monitors.
-michael
AppleCrate: An Apple II "blade server"!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it's seriously underused."