On 3/24/2013 3:18 PM, Alex Freed wrote:
By the way sampling the bus doesn't have to be that fast. The Carte Blanche does it a 50MHz.Gentlemen, CB doesn't "sample" the bus at all. Instead it reacts to the 6502 accessing the bus. Just like say a memory card would. Totally different concept.
I stand corrected on my terminology. My CB, however, "reacts to the 65816 accessing the bus" ;-)
Video sync is a solvable problem. Either take the signal where it is available (IIe slot 7, etc.) or write a program that will allow the VGA card/software to sync.True. Maybe even write a signature to the beginning of the video memory and sync to it. Once in sync it should stay in sync till a reset, so the signature doesn't need to stay there longer than a few milliseconds. -Alex.
I would prefer a method that doesn't require interfering with the operation of the Apple.
I also don't understand why it would necessarily stay in sync. Is it safe to assume that the Apple's crystal and the Carte Blanche crystal are so close to the same frequency that they would not drift out of sync in a noticeable amount of time?
I think Sheldon's idea of putting the card in slot #7 and using the sync signal (pin #19) is a better idea because there is no need for programs and/or signatures and the card could continually check if it was in sync. Of course that leaves out the Super HiRes graphics modes.
Charlie