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Re: Let's pay a developer to make a VGA output card
Scott Alfter wrote:
As a quick experiment, I tried plugging a IIGS into my HD LCD TV. Instead
of running a cable from the composite output on the computer to a composite
input on the TV, I ran it from the composite output to the Y input on one of
the TV's component inputs. The image wasn't 100% stable (there was some
flickering), but 80-column text was easily readable. I suspect that a
CRT-based TV (SD or HD) with component input would work better. A
higher-resolution LCD and/or one intended for computer use (which will have
a button to make graphics more stable for the currently-active mode) might
also work better.
Most LCD displays don't extend their "fine sync" option to composite or
S-Video input. The way these modes work is to phase lock to the dot
clock of the incoming video, but the usual assumption is that TV video
is analog, and does not have a dot clock to lock to.
It should be possible to make an adapter to convert the IIGS's RGB output to
component video that would be usable on a growing number of TVs. Since no
scan doubling would be necessary, the design should be simpler and cheaper:
a handful of op-amps to convert from RGB to YPbPr, and something to mix the
composite sync provided on the GS's RGB port with the Y signal. There are
even computer monitors with component input, so you could use one monitor
with your GS and your newer boxen. (I saw a 21" widescreen Samsung at
Costco last week that would be a nice upgrade from what I have
now...somewhere near 1600x1000, with all the inputs you could possibly need:
DVI, VGA, component, S-video, and composite.)
I suggested this approach a year or so ago, and even pointed someone to
an App Note that explained how to use the ubiquitous video op amps to
do the conversion, but I never heard any results.
It's pretty simple, with three op amps and a handful of resistors...
There remains a more fundamental problem: That 280x192 is not very many
pixels, so they will never look good if they subtend more than a small
solid angle in your visual field. In other words, if you get close to a
large screen display of Apple II graphics, you will not like 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."