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Re: IIgs RGB to YPbPr Component experiment
jsnospam@cimmeri.com wrote:
Michael J. Mahon wrote:
Looks quite usable!
Oh, yes, quite. In fact, the text is the best I've seen so far after
the AppleColor RGB monitor. In my opinion, easily beats the Commodore
1084. The pictures here are not quite as good as the reality as the
shutter speeds were 1/8 sec and 1/4 sec respectively, and my elbows on
the desk comprised the bipod.
The 80 col text in GSOS is perfect. In Prodos, there is a barely
perceptible, negligible flaw (I think) if you look closely.
Yes, I see the occasional "thin pixel" vertical stripes. These
correspond to places where an Apple pixel maps to just one LCD
pixel, while most map to two adjacent LCD pixels.
The fact that the display is stable (no wriggling vertical lines)
indicates that the LCD sampler has locked to some rational fraction
of the Apple dot clock. The periodically varying widths of Apple
pixels as displayed on the LCD indicates that the sampler is not
running at an integer multiple of the Apple dot clock.
Given how much better this method is than the black box VGA
upconversion approach, I'm not holding out much hope that that method
will ever rival it. We'll see.
I'm planning two VGA upconverter tests: one using the Aussie's Highway
SCART RGB->VGA converter (more sophisticated than the earlier #41 board
I first reported about elsewhere here); and another using the Averlogic
chipsets.
A true scan conversion from NTSC scan standards to VGA *could* produce
a rock-solid display--if the sampler locks to the Apple II dot clock
(14.3MHz), but this would only work if the size of the Apple display
on the LCD caused it to occupy an equivalent number of LCD pixels,
which would call for some "windowing" in the converter.
For example, a 560-dot Apple screen could be beautifully mapped to
560 LCD pixels, or 1120 LCD pixels.
-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."