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Post by hydrophilic on Jun 1, 2021 7:09:49 GMT
I've been informed by a Canadian Commodore enthusiast of a possible run of RGBI-> VGA boards. These can be used to connect your 80-column VDC to a VGA-compatible monitor. Some (mostly older CRT-type) VGA monitors will work DIRECTLY with C128 native horizontal frequency of 15.75KHz... a few modern/LCD monitors will also DIRECTLY work. If your monitor REQUIRES a higher frequency (31.5KHz) then a CGA(aRGB)->VGA converter would also be needed. Below are two sides of a production mock-up board he provided: If this is something you are interested in, please comment and I will forward your messages to him. With enough enthusiasm I might persuade him to join the site and post comments directly. I assume (but can't guarantee) that more responses will push this prototype into production. It seems his biggest concern, currently, is that various monitors respond differently to H/V sync. He has a plan that should hopefully work with most/all monitors, but is currently under active research.
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Post by robertb on Jun 2, 2021 7:29:24 GMT
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Post by hydrophilic on Jun 6, 2021 12:00:40 GMT
Thanks RobertB for link to BIT-C-128... I've never heard about this before! I've never used BIT-C-128 myself, so I can only speculate... I searched the website you referenced, but although they have pretty pictures, I never found any electrical schematic so I can not say what is different / better / etc. What I can say is that is that Kilbert's board is based on an electrical schematic that is publicly available here. I will tell him about the board you posted... more options are better for the C128 community!
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Post by robertb on Jun 6, 2021 18:57:11 GMT
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Post by hydrophilic on Jun 10, 2021 7:27:52 GMT
Thanks for the info. My search, per your suggestion, gave many results, but this one seems to be the most relevant. I remember contributing (well at least posting in response) to RichardB's design of a Video DAC. I didn't realize that John Carlsen had made a production run, announced in this thread, of RichardB's design (if I understand correctly). Anyway if it is based on RichardB's design, then it should be very similar to the one in the first post of this thread. The only difference I can imagine is the handling of Orange and Dark Gray. It seems like there was analog mixing with RichardB's Video DAC, while the one by the Canadian (original post in this thread) uses a digital circuit. As long as it works for Commodore users, I don't care. I'll inform the potential manufacturer about all of this.
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Post by robertb on Jun 10, 2021 21:20:29 GMT
I didn't realize that John Carlsen had made a production run... He has made several runs of his C128 Video DAC. John's design has accurate 80-column colors, compared to Richard's which Richard himself said to me had incorrect colors. That brown fix was important, Robert Bernardo Fresno Commodore User Group - http:/www.dickestel.com/fcug.htm Southern California Commodore & Amiga Network - www.portcommodore.com/sccanNov. 6-7 Commodore Los Angeles Super Show - www.portcommodore.com/class
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Post by hydrophilic on Jun 15, 2021 6:38:33 GMT
Totally agree, the "brown" is important. One issue is vocabulary! Many (most?) people wouldn't describe that color as brown... from my memories of C1902 monitor, comparison with VICE, and various discussions about CGA/RGBI across the web, it is more like a dark orange. "True/Digital" brown would be low-intensity version of yellow, but the CGA/monitor manufacturers/IBM-standards fudged the RGBI value with a lower (50% standard) green ... which effectively means increased red.. I hope we all agree dark yellow + red = dark orange! I'm glad John reports accurate colors. Richard's design used analog, while the solution in initial post is all digital, so hopefully just as accurate as John's. Since I couldn't find any technical data on John's website this is speculation, but seems reasonable to me. I built and tested my design before publication, so I can tell you my design looks like dark orange on either VGA monitor (direct) or with CGA/VGA adapter (at least Amberry model I tested). This new Canadian design seems to be the same, but I haven't received a prototype from him to test myself. Anyway, thanks for sharing robertb . I've sent an email to the speculative producer about all this, but haven't seen a reply yet... I guess I need to go check my email
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Post by blindguy on Jun 15, 2021 19:09:10 GMT
My buddy Sven Pook is making his version of a 40/80 col C128 adapter. V5 now has SVIDEO support. c128adapter.pook.nl/
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Post by tokra on Jun 15, 2021 20:47:15 GMT
That one has a nice design and is very affordable, but it does not have the "brown fix" (not a surprise at that price-point). I am currently using this adapter right now: github.com/JDet-74/C128toSCART_SMTYoutube: www.youtube.com/watch?v=qOvFwwrAEIkAt 38 EUR it is more expensive for a built unit, but comes in a nice box, has the brown fix and provides S-Video for 40 column as well (it can also be switched to FBAS/composite). The only thing missing is an option to turn off the "brown fix" so you get dark yellow. There just might be a reason in the future you want dark yellow... Otherwise it is close to perfect I think, but I am still probably going to need Sven Pook's adapter for "dark yellow"
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Post by robertb on Jun 16, 2021 18:01:51 GMT
...so hopefully just as accurate as John's. Since I couldn't find any technical data on John's website this is speculation, but seems reasonable to me. FWIW, John designed his C128 Video DAC by testing the colors with two Commodore 1084-S monitors. Truly, Robert Bernardo Fresno Commodore User Group - www.dickestel.com/fcug.htmSouthern California Commodore & Amiga Network - www.portcommodore.com/sccanNov. 6-7 Commodore Los Angeles Super Show 2021 - www.portcommodore.com/class
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