Re: Apple][VGA - finally available

[Mark McDougall <msmcdoug@no.spam.iinet>]

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.

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.

> 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.

> 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.

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.

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.

Regards,

--
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"