Re: Apple II+ 80-col video conversion

[Michael J. Mahon <mjmahon@aol.com>]

Curtis Schroeder <publicpanther@gmail.com> wrote:
> First, let me say I know this is not a new subject.  But my recent
> research suggests it is time to revisit this topic because the previously
> recommended CYP CM-345S / 15K RGB Composite Sync to XGA Converter has
> been discontinued (more on this below).
> 
> What I am looking for: recommendations for stand-alone video converters
> that can render crisp Viewmax-80 video on an LCD monitor using either VGA
> or DVI *or* a PCIe 1x video capture card using either Ubuntu Linux
> (preferred) or WinXP.  Based on my research thus far, the unanswered
> question is whether a video product that specifically supports NTSC 4.43
> (60Hz) is likely to provide a satisfactory solution for scan converting
> ][+ 80-col video?  The specifications of the Apple /// monitor suggest
> the answer is yes, but I've not found any conclusive information.
> 
> I already have a Grandtec GRAND Video Console (also discontinued) that
> does an adequate job displaying the standard video modes output by the
> ][+ and does even better now that I have switched to the S-video input
> (feeding the composite video signal to both the luminance and chroma
> inputs), but it fails to sync with 80-col video.  At this point, I am
> actually more interested in a PCIe 1x video capture solution and I have
> not found any information in this group about this topic.
> 
> Regarding the previous FAQ answer, the converters.tv site suggests two
> possible replacements for the 15K RGB
> (http://www.converters.tv/products/pal_to_vga/100.html).  These are:
> - SCART Video to XGA / HDTV Converter
> (http://www.converters.tv/products/pal_to_vga/187.html),
> - YUV to RGB Converter(CM-333 / CYU-333)
> (http://www.converters.tv/products/rgb_to_rgb/28.html).
> 
> Another possibility might be the Ambery AV-9 (http://www.ambery.com/3x2vitohdvga.html).
> 
> Does anybody have experience with these converters with respect to
> IIe/c/gs video so the FAQ answer can be updated and additionally whether
> they support ][+ 80-col video?  Another information resource I've found
> in my search that may be of particular interest to IIgs owners is here:
> http://retrogaming.hazard-city.de/
> 
> Again, what I am most interested in is recommendations for a PCIe 1x
> video capture solution or more detailed ][+ 80-col video information that
> might allow me to make an educated selection, i.e. do I need NTSC 4.43
> support, advanced de-interlacing, or both?  What feature(s) made the 15K RGB successful?
> 
> Curt

The fundamental problem for any video sampling solution (any non-analog
solution) is the coherence of the video sampler with the Apple's video dot
clock--14.3MHz for most modes and 16MHz for IIgs SHR mode. 

If the converter dot sync range accommodates these frequencies, the output
can be sharp and alias-free. 

For good 80-column text, 14.3MHz is the critical frequency. Sampling at any
integral multiple of 14.3MHz will result in crisp, non-aliased text. 

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon