Note to forum master: a sub-thread with a title like VIDEO seems appropriate (C128 > hardware > video).
Anyway, I wanted to tell everyone about my "new" RGBI-VGA solution. Personally, I have posted (in the past) several COMPOSITE solutions, and one or two VGA solutions.
However, none of my former "hardware hacks" gave "true" C128 colors... usually the "brown" would display as "dark yellow". (Look HERE)
But I finally did it!! I made a device that gives all 16 VDC colors (including the bastard "orange/brown"). I built it for some guy on eBay who paid me a generous amount of money... anyway, it works great and I want to share this idea with everyone in the CBM community.
Although there are many alternate ways to build such a device, my solution is quite simple... it requires only 2 "standard" (easy to buy) ICs... I would tell you what they are, but my Microsoft PC is being a bitch right now... In other words, stay tuned... I will update this page with a complete solution (after I discover why MS sucks)....
I am interested in all these options to convert composite and / or RGBI to VGA. But also I would be interested in finding out what is available as a kind of switch selector to the VGA monitor for the two signal coming in.
As far as switching is concerned your best bet is a passive VGA switch box. These are only a few quid on eBay now.
My monitor supports both 15khz and 31khz on the VGA input so I can switch between real VGA signals and the CGA on the 80 col with ease. Sadly the S-Vid to VGA looks like total shit so my plan to use that on the VGA monitor is on hold. I must try the actual composite picture to see how that looks. I don't even have a composite cable at the moment!
I am still interested in hydrophilic's solution with only 2 chips More details please!
(btw, I obviously say that MY version is the best. I would recommend it if I could actually build them as fast as I sell them).
I built an RGBI-to-VGA converter (all 16 colors) for a customer last year (2016). I haven't had the time to publish the details (shame on me). Anyway, once I get some time, I will publish my solution for everyone/anyone to use/build it for themselves. Of course, if you want HDMI, then an extra layer (VGA->HDMI) would be needed...
(Damn it!!! I tried to add extra images/details, but failed... stay tuned for more!)
I am also interested in that answer! I currently have a flat panel monitor (actually, two of them but one has no stand) which will display S-video for the VIC-IIe screen, plus another dozen or so not currently in use which almost all take DVI, and I’ve been watching with great interest the recent developments concerning native VGA generation by the VDC, but I haven’t yet decided on a specific method of converting standard CGA output to any of the suboptimal formats supported by my extensive collection of lightly damaged thrift-store flat panels.
The world’s only gsteemso
Agitator-in-chief for the Seattle Retro-Computing Society
Hello everyone who has been waiting for an answer, and greetings to anybody else who just popped in to see "wutz-up"! (It's been a long time since I posted...)
Anyway, I just want to tell you about YET ANOTHER RGBI -> VGA solution. Although I've published several RGBI converters (to Composite / S-Video / VGA) in the past (trust me or search...), this new one is, perhaps, the Ultimate!
This adapter gives all/true 16 colors (and from my limited testing, works for all 4 "standard" VDC modes:
Standard Text (80x25)
Interlaced Text (80x50)
Standard Bitmap (640x400)
Interlaced Bitmap (640x800)
I am sure there are other posts about an RGBI adapter that gives all 16 colors, and I thought they were made by "RichardB" ?? But I've searched this forum and couldn't find those posts... Perhaps I am thinking of the old C128 Forum hosted in Australia??
Since I can't find those old posts, all I can do today is give you my opinion ("fuzzy memory") of how that old adapter (might have) worked and how my recent adapter (definitely) works...
As I recall (flame me if wrong), RichardB used an array of DACs (digital-to-analog converters) to produce a "suitable" RGBa output using the C128/VDC (RGBI) as input. As I recall (again, flame me if wrong), there were 4 DACs, (one for each of R/G/B/I), and each DAC had associated resistors (etc).
Hopefully someone can find/post his circuit for comparison...
Regardless, I am here to tell you about a relatively simple circuit (minimally 2 chips and about 10 components [resistors/diodes]) which I have designed, built, tested, and sold. Basically you need my RGBI -> RGBa circuit plus an "off-the-shelf" RGBa->VGA converter. The following describes the use of the Ambery VGA adapter, but there other adapters (even non-VGA, like S-Video) which work with my circuit...
I think I posted this before, but just in case, here is my simple RGBI -> RGBa circuit...
My circuit gives "crisp" outputs for all 16 colors, including the pesky "Dark Gray" and the notorious "Brown". My circuit needs [in general] to be connected to a "VGA Converter" (like the Ambery model) for use on a "modern monitor"... but you can also connect my circuit to an S-Video Converter (changes may be required). Anyway, if the final (VGA/S-Video) converter works correctly, then my RGBI "Ultimate" circuit should give you maximum color fidelity (in particular, the bastards "Brown" and "Dark Gray").
Just in case anybody thinks I am making-up, $h!T, bellow are two "real-life" images. The first is the circuit board (made from the schematic above) which I personally assembled, and the second is a photo of a real VGA monitor (showing all 16 true. colors of the C128/VDC).
I like to think of this solution as the "Ultimiate". But that is my opinion... view all the images on this page (above and below) before you make a conclusion. Once you decide, please report your opinion... I will love your regardless!
Last Edit: Mar 12, 2017 10:06:27 GMT by hydrophilic: Added links to Richard42 and his old Commodore128-Alive! forum post
I use a programmable logic device to turn RGBi into RRGGBB with the brown fix done digitally inside the logic. I then use a 6bit DAC to convert the new RRGGBB to RGB Analogue.
So far, I have not seen any adapter that comes close to the quality of the output from mine and sadly your photos are not showing so I can't compare. I do get from your text though that you have only done the digital to analogue part of the circuit (same as me) with no scanrate conversion. I designed mine to work directly with the Gonbes by having a 15pin VGA style connector for it's output which connects directly with a common cable to the gonbes for VGA upscaling.