according to the Compatibility Matrix (as of 09/11/12) the VGA cape and the DVI-D with audio cape look like they will work together in the same stack. This looks like an error, but is it? Does adding audio capability to the DVI-D cape really let us have VGA and DVI-D in the same stack? (generally it appears that one can have but a single display cape in a stack, probably due to pin contention issues)
It really depends on the displays. There is nothing electrically that make them unable to be used at the same time. All the pins used are inputs to the cards. The issue becomes if the timings that are used on both interfaces can be the same for two different displays. If they can, then it should be able to drive a VGA and DVI-D to two different displays at the same time.
Audio and display interfaces are seperate and the VGA does not use the audio interface. So, you can have VGA and audio with this combination.
What’s interesting here is that the VGA and DVI-D with audio capes show as being compatible but VGA and DVI-D without audio capes not being compatible, thus my comment about adding audio to the DVI-D cape and suddenly having cape compatibility. If the DVI-D with audio cape is compatable then I’d expect the DVI-D cape without the audio circuitry to also be compatible. any idea why the addition of audio to the DVI-D cape suddenly makes it compatible with the VGA cape? You mention that you can have VGA and audio with the VGA cape + DVI-D audio cape combo, but what happens to the DVI-D video out in that combination?
Yes I know. This is brand new and still being reviewed and updated. I expect it to under go about 25 -30 revisions before I consider it solid. We need to add more information to it to explain certain corner cases and exceptions. It is just a start.
If you want something 100% perfect, then don’t look at for a month or so.
Again, I appreciate your work on this and unfortunately as more capes come available it just becomes exponentially more complex. Don’t expect it to be perfect but figured I’d ask about a case of interest. If there’s anything I can do to help work out what works with what, please let me know.
If you have any other observations, just send them on. The people putting this together are not exactly experts on these different capes unfortunately.