VGA / SVGA Card / Adaptor for the ][+?

[robc638@startmail.ca (Robert C.)]

Is it possible to make a card or adaptor that will convert the
composite video signal generated by the Apple to display on a VGA /
SVGA monitor, maybe even increasing colour quality?

I have been looking at a way of doing this, but I am stuck on how to
decompose the video signal. One possibilty would be to tap directly
into the Apple's portion of RAM where the video image is stored,
taking into account the lo-res, hi-res and text areas, and switching
the memory locations, and then convert this into RGB for output to the
VGA monitor.

Another approach would be to have the Apple "write" to a memory bank
equivalent of the monitor, then "read" back this "memory map" through
RGB to the SVG output.

Sync-ing would be done using a PLL running as a multiplier of the
Apple frequency to achieve the 72Hz required for VGA sync.

Any ideas or suggestions?

Thanks.