On 10/6/2011 9:28 PM, Michael J. Mahon wrote:
Charlie wrote:On 10/6/2011 5:13 PM, IUnknown wrote:
>>> snip <<<
Until a hardware device is available that will perform a 'true' conversion of the IIgs video signal to VGA, we are pretty much stuck.A hardware device doesn't have to 'convert' the IIgs video signal to VGA. It can generate the VGA directly from the video data in the Apple memory. This is the way the Second Sight card works (I believe) as well as the Carte Blanche card. However, solution 1 (finding a compatible monitor) is probably still the easiest and cheapest and overall gives adequate results.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.
By the way the biggest problem I 'do' see is rendering a faithful double hires mode instantly. There seems to be no algorithm available for determining the pixel colors in all instances.
Converting the video output is by far the most compatible approach, and it's not difficult--it's just that none of the currently available devices was designed to convert video generated by an Apple II (or an Apple IIgs, for which SHR is a special problem because of its 16MHz dot clock).
I shouldn't argue since I don't know how to do it myself, but to my knowledge no one has made an Apple IIgs video converter. It seems to me that if it is easy then someone in the Apple II community would have done it by now. I believe there have been people working on it for some time. On the other hand there is the Second Sight card. I don't own one so I can't testify to its video quality but it was at least made for the IIgs.
> snip < Charlie