VDC conversion to VGA/HDMI

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).

Still waiting to hear if you actually mean RGBI to VGA or just to RGB (does it output 15khz or 31khz?)

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??

[Edit] I was thinking of Richard42, who posted a converter for sale on the former Commodore 128 Alive forum. [/Edit]

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!