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Re: Let's pay a developer to make a VGA output card
Mark McDougall wrote:
heuser.marcus@freenet.de wrote:
Give me a graphics option that looks like the output of an old 14''
color monitor of yore. Give me pixels that aren't square or blocky
but smear into their neighbours. Give me pixels that get "thicker" in
height and width the more contrast the picture has.
Seems there are two distinct schools of though here...
The primary reason for wanting VGA of course is being able to use
existing VGA monitors, whether that's simply for space-saving (which
would be my reason), an ever-depleting stock of compatible monitors, or
simply convenience.
One 'school' would appear to be happy with 'perfect' display quality -
the crispness of modern displays as is possible on the emulators.
Arguably, a simple 'scan-converter' is out of the question for this
purpose. To add complexity, there's also the 'artifact' mode which would
have to be implemented, even if it results in a similarly 'crisp' display.
Then there's the school that want an exact replica of the old analogue
output with features such as Marcus has listed above. These features are
ironically more difficult to produce artificially from a pure digital
source. Perhaps a scan-converter of sorts would be more suitable here.
Personally, I like the idea of the 'bus snooper' with its own frame
buffer to produce VGA output. Yes, without any processing it would
result in the 'clinically sterile' output but with a more capable (and
costly) design these issues could be addressed somewhat.
I've had some experience with FPGAs and VGA generation and I am sorely
tempted to build a prototype card... I have a few ideas of what else
could go on the card as well. But can the A2 hobbyist market support the
cost of even just producing such a card? I'm debating that myself...
I understand your preference, but I think you would find it much simpler
in reality to build an "Apple scan doubler" that grabbed the dot clock
from the Apple (AUX slot?), sampled the composite video signal (it's
digital, after all), and "played it back" at 2x the scan frequency for
a VGA monitor, using an appropriate RGB conversion. This would produce
an "emulator style" VGA display, which, I expect, would satisfy many
users--though perhaps none perfectly. ;-)
-michael
Parallel computing for 8-bit Apple II's!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it is seriously underused."