Re: Supercard

mdj wrote:
Michael J. Mahon wrote:


Actually, the "sliding window" approach, with 8 or 12 bits, would
do a fine job of creating accurate artifacts. This should be
particularly easy to try in an emulator, but it could also be used
with a hardware VGA adapter.

There would only be as many horizontal pixels as there are on an
Apple II, so if you wanted to fill the screen, you'd have to scale
it up, of course (integer multiples are easy).


Just conscious of the fact that there's not that much more raster
resolution, even on a modern display. If conserving the aspect ratio is
a part of the goal, it's quite tricky. You need a 560 wide raster
pattern, which is easy enough to do as VGA with a basic scan doubling
technique, but to drive higher res it's much harder.

A target for me would be digital panels, as I'm essentially removing
VGA monitors from my house. You basically have two target resolutions
in that case: 1024x768 or 1280x1024 on the larger panels. 1280x1024
would probably be ok, as a 1120 wide raster would be reasonably close
to Apple II aspect, but you still only have 8 pixels to play with for
the colour information, which might not produce a very nice emulation.
Proof of course is in trying it :-)

Of course there are just 560 Apple pixels, so a full screen display
may look pretty fuzzy if you're close. Quarter screen might be just
right.

I'm not sure what you mean about "8 pixels to play with", since each
VGA pixel can be any color, and the sliding window shift register
algorithm can index into 256 (8-bit window) or 4096 (12-bit window)
entry palette tables. The luminance info would be included in the
RGB values, of course, and could (optionally) be kept quite "sharp".

Most current RGB adapters keep the luminance maximally sharp, so
that the individual "1"s in the video are quite visible. Some may
like that look.

I'd just like to see a good RGB/VGA emulation of a composite display,
so that many more things would look as they were designed to look.


Same. The main thing to keep in mind is that (double) hires really
needs mono and colour handled seperately, as this was usually taken
care of by a physical switch on the composite monitors. DHR mono
applications (ie. most of them) are unusable on a colour display unless
you implement the colour killer, but even then it's worse than a
monochrome display.

Of course a monochrome mode would be a must-have, and trivial, since
only two colors need be displayed. Full bandwidth would characterize
the mono display.

All of these rendering options (faithful composite, traditional RGB,
and monochrome) are easily accomodated by a look-up table change
as I see it.

-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."
.

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