I am trying to research a new composite video to VGA/DVI solution, but I'm finding very little information on the web that describes the video specification of the ][+ 80-col video signal.
One can safely assume the 40-col video and hi-res graphics modes comply with NTSC 3.58 and I have learned that NTSC 4.43 displayed on a standard NTSC display results in a monochrome image, which would be consistent with ][+ 80-col video. Additionally, the specifications for the Apple /// Monitor reveal it supports more scan lines than the typical NTSC TV display and thereby can support the 525 scan lines required by NTSC 4.43. The use of additional scan lines is consistent with 80-col video having a different aspect ratio from the 40-col and hi-res graphics modes on the Apple /// Monitor.
Can anyone confirm the ][+ 80-col video is indeed NTSC 4.43 and is properly displayed by video converters or PC video capture cards that specifically support NTSC 4.43?
Best regards,
Curt
You may wish to review the extensive research that others have already done on the subject. Head over to comp.sys.apple2 with Google Groups and do some searches. You will find very much information, including that from experts on the Apple II video signals. Look specifically for responses from Michael Mahon.
Well, the Apple II+ never had an 80-column solution from Apple Computer, Inc., so that might be why. 80 columns came from third party add-on boards.
You can make no such assumption. Woz famously skirted the edges of NTSC and loosy-goosy televisions of the era were able to comply. That's why things really get erratic when you hook up an early Apple II to an LCD monitor that actually expects a signal that conforms to NTSC.
Again, from which card? Videx put out a number of popular ones. There were several others.
I have the Micromax Systems Viewmax-80, which I understood to be a Videx-80 clone and provided beautifully crisp 80-col text when I had access to my Apple /// monitor.
I apologize, I thought I had done adequate due diligence, having spent many hours scouring the web using Google prior to posting my question, but despite having been a regular reader of comp.sys.apple2 (and occasional contributor) two decades ago I confess had forgotten about it. I took your advice and conducted a more careful search of comp.sys.apple2 using Google Groups, but I didn't find much information specific to ][+ 80-col video conversion. Most of the information there centered around the unique video needs of the //gs and to a lesser degree the double hi-res output of the //e & //c, but their favored video converter, the CYP CM-345S / 15K RGB Composite Sync to XGA Converter, has been discontinued. I will pursue identification of potential currently available alternatives in the comp.sys.apple2 group.
I did find a small hint that was immediately useful. S-video converters support slightly higher frequencies than composite video converters, so one trick is to connect the Apple ][+ composite video feed to both the luminance and chroma S-video inputs. I have verified this allows my Grandtec GRAND Video Console (also discontinued) to output a slightly cleaner VGA video feed for both 40-col and ][+ hi-res video and is quite adequate for my ViewSonic VG2021m LCD. I also found one converter configuration that provided legible 80-col text, which was never possible using the composite input, but alas it was static, i.e. it did not update after the first frame capture by the converter. I expect the additional scan lines confuse the GRAND Video Console and consequently it doesn't sync properly. I believe this implies my Grandtec converter only supports NTSC 3.58.
The documentation that came with my Viewmax-80 and Grandtec converter are both sorely lacking of detailed video specifications, which is what makes this so difficult. I am still wondering if a video converter that promises NTSC 4.43 support would be sufficient for ][+ 80-col video conversion.