Jason wrote:
On 2009-05-02 14:40:07 +0700, "Michael J. Mahon" <mjmahon@aol.com> said:Jason wrote:On 2009-05-01 19:16:32 +0700, gozarcollins@SPAMTRAPhotmail.com said:Jason <jasonb1963@yahoo.com> wrote:Video: I'd like to use an existing LCD panel display I have (with VGA input). I note that several companies manufacture composite video to VGA converter boxes for $40-$60. Can anyone comment whether this produces an acceptable display? I'd prefer to avoid dealing with an older CRT if I can avoid it.I use a 15" LCD TV for my 800XL and it's ok. The colors seem a little subdued. It has composite/s-video/VGA inputs. Here's a picture of it (if you want I can take a more up close picture, in fact, I could plug my IIc+ into it and take a picture)): http://gtia.com/wp/2005/12/29/old-school-meets-new-school/It would be interesting to see how it works on on the //c+.For the Atari, I hear the best thing to do is to pick up a set of custom s-video cables (the 5-pin DIN connector has s-video output on it) and use that to drive an s-video input or an s-video to VGA converter box. Others have claimed this works really well. From the pictures I've seen, I'd have to agree.S-video represents color information as QAM on a 3.58MHz subcarrier, so all chroma is fundamentally limited to 3MHz, and practically to bandwidth in the 1MHz-2MHz range. The effect is that fine detail can only change color slowly, so fine vertical lines that have the same luminance (brightness) levels as their surround, differing only in chroma, will have their contrast and chroma noticeably diminished.Yes -- approximately 160 colors per horizontal line. Still, S-video looks a lot better than composite video and was quite popular up until Y2K or so.
I agree that it is considerably better than composite, mainly because the luminance bandwidth need not be limited by the chroma subcarrier frequency. This permits acceptable 80-column text rendering, though it doesn't guarantee it (depending on the LCD's resampling of the Apple video).
An excellent example of this fundamental limitation of S-Video is visible in a DVD of Star Wars connected to a monitor via S-Video. As the opening text scrolls "back" to infinity, the width of the font verticals diminishes considerably, and you can easily see that then characters, gold when wide, fade until all golden color is gone as they shrink. This effect does not occur when chroma information is provided with wider bandwidth, such as with Component or RGB connection.Which 8-bit vintage computers offered component or RGB (same thing) video output? Certainly neither the 8-bit Ataris nor the Apple // series. The Atari was ahead of its time by offering s-video output 3 years ahead of anyone else.With the 8-bit Apple // series, you are limited to composite video only. Sure, Alex has produced some FPGA-based boards with the ability to provide VGA output for the //, //+, and //e. This is great if you have a larger // series and can afford one. For those of us with the //c, we are stuck with composite video output for now -- at least until someone finishes one of the pieces of vaporware which were referenced earlier in this thread.
There were a couple of RGB adapters for the //c and //c+ (Video 7 is one I recall by name). These were small adapters that screwed onto the video expansion port. But I was simply stating the primary limitation of S-Video, not suggesting that you had to go to RGB. -michael ******** Note new website URL ******** NadaNet and AppleCrate II for Apple II parallel computing! Home page: http://home.comcast.net/~mjmahon/ "The wastebasket is our most important design tool--and it's seriously underused."