Re: Apple][VGA - finally available

["geoff" <geoff@a2central.com.remove-oci-this>]

  To: Michael J. Mahon
Apparently, this is where you and I disagree.  I believe the model which the 
Second Sight uses to generate Apple II graphics modes is far superior (reading 
video from the bus) than what else can be accomplished.  I don't disagree that 
the Second Sight card with its 10 MHz CPU and the OTI SVGA chipset is less 
attractive today.  Neither would be a problem if redesigned with modern 
components.

Before we can close the door and say that the Second Sight is a failed model, 
there is code out there that provides GS/OS desktop on the SVGA resolution 
screens.  It never got released and I don't know how complete it is.  Perhaps 
there should be an attempt to ask for it to be open sourced since there 
doesn't appear to be any commercial support for it now.  Maybe somebody else 
would be interested to pick up where it was last left off.

Geoff

 > geoff wrote:
 > >   To: Michael J. Mahon
 > > TYhe Second Sight performs various functions, including an Apple II/IIgs 
 > > video to VGA converter (this is how most Second Sight owners use their 
 > > card).
 > 
 > > The nice thing about the Second Sight is that if you don't like the RGB 
 > > display is generated, you can write your software code to make it do 
 > > something different.  You don't have to burn your ROM--just write a 
 > > driver when the OS boots.  Jut because nobody has done this doesn't mean 
 > > that it doesn't have the capability.  It becomes really easy to support 
 > > enhancements when no hardware changes are needed.
 > 
 > The fact that nobody has done this is a testament to the difference between 
 > making a thing *possible* and making it *probable*.  ;-)

 > That this possibility is even discussed sounds like saying "it's 
 > programmable, so if the designer(s) didn't make it work well, you
 > can fix it yourself".  ;-)

 > > If you want to immediately make HGR look horrible by adding NTSC 
 > > artifacts, there is nothing to prevent you :)
 > 
 > Actually, I think you would find that the Second Sight doesn't have
 > nearly enough processing to provide proper NTSC effects digitally.

 > You may be missing some of the context...

 > This is part of a protracted and intermittent discussion on how to best and 
 > most economically provide the capability of connecting an Apple IIgs to a 
 > modern VGA display--both because of fears of analog RGB monitors failing 
 > and because of the convenience of being able to share monitors with modern 
 > machines.

 > As with any engineering problem, there are several possible approaches.

 > One is to tap into the RGB signals (digital preferred, but analog OK) 
 > inside the IIgs and, with as little fuss as possible, use them to
 > create a VGA RGB stream.  A few have had good success with converters using 
 > "NTSC" scan standards RGB in and providing VGA RGB out.  There
 > have been experiments using the digital RGB in a similar way, but no 
 > product yet.  (Critical issues are the relation of the sampling clock
 > to the Apple dot clock, and the bandwidth of the video processing--not
 > too much, not too little.)

 > 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...

 > If it isn't clear  ;-), I think that the latter approach--the one taken
 > by the Second Sight card--is a failed strategy.

 > 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.

 > Finally, the vast majority of Apple II graphics are not IIgs graphics-- 
 > they are Apple II graphics designed to be viewed on analog composite 
 > monitors, where the subtleties of color and the pleasant lack of
 > detail (that cannot be represented in Apple II video) is an artistic
 > match to the designer's intent.

 > I certainly wouldn't want to use it for text displays, but there are 
 > hundreds of hi-res screens that only represent their designer's intent when 
 > viewed with limited color bandwidth, and that look positively gruesome in 
 > standard RGB modes (think dithering).  So any VGA converter should offer 
 > the *option* of processing the video with NTSC artifacts.
 > Not offering this option would mean that I would need another monitor
 > on my desk just to view these graphics properly.

 > 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.

 > > Geoff
 > 
 > >  > Dave Althoff, Jr. wrote:
 > >  > > Ferdinan Meyer-hermann
 > >  > > <ferdinan.meyer-hermann@a2central.com.remove-rw3-this> wrote: :  > 
 > >  > > Why did you not add support for the IIGS?
 > >  > > : So you'll have to wait until someone designs a "GS2VGA"...
 > >  > > : A real GS2VGA would also have the advantage of being cheaper and 
 > >  > > drawing less : power than a combined solution. And it is likely to 
 > >  > > cause less trouble
 > >  > 
 > >  > > Anybody remember the Second Sight board?  8-)
 > >  > 
 > >  > That's not a IIgs video to VGA converter.
 > > 
 > >  > The Second Sight was a much more problematic "VGA card for the IIgs" 
 > >  > with the consequent need to support new graphics modes, as opposed
 > >  > to simply converting IIgs RGB video into VGA video.
 > > 
 > >  > The trickiest part of such a conversion would be a mode to handle 
 > >  > NTSC-like color rendition (instead of the much higher bandwidth and, 
 > >  > for many graphics, less attractive "digital RGB" modes) for Apple II 
 > >  > video.
 > 
 > -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."