Hey, I didn't say "Mine is the best" I said it was the best I have seen I really wanted to compare the output but sadly those photos just don't show for me.
It's true that they all mostly work the same way but there are some facts that greatly change the quality of output.
A logic based solution is better than a passive based one. Trying to get the intensity bodged in with resistors and diodes/transistors is never going to look as good as doing it all in logic then using a DAC to get the output. Any logic based solution is going to be judged on the speed of the logic chips used. Not only is absolute speed important (if they don't switch fast enough you get poor edges on the colours) but having the gates switch at the same speed is critical too. There are more gates involved in the brown colour than just r/g/b etc. This can lead to artifacts on the edges of certain colours.
So there is a whole wide scope of variation in adapter. When I started making mine it was pretty much the only design other than the basic resistor circuit out there... I did it to encourage more use of the VDC and 80 columns. I think I achieved my goal, it's great to see other people working on it and more people using the 80 column chip. Even if it is a little bit late.
No, Pyrofer, I am not aware of your adapter! Can you post a screen-shot or a schematic diagram (or, preferably both) so forum members can compare? Or at least a link? Thanks! [Edit] To be fair, here are some links to most of my published adapters:
I think my latest, "Ultimate" version (published in this thread) is a great compromise between quality and cost/complexity. Of course this is just my 100% biased opinion, so everyone feel free to comment! [/Edit]
Last Edit: Mar 10, 2017 9:30:47 GMT by hydrophilic: added links to demonstrate "reality" to Pyrofer who talks without any support
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??
Thanks RobertB! I thought those old forum posts were forever lost!! Well it seems the attached images are missing, which is really, REALLY bad... but we can't blame RobertB for that
Richard42 used an array of DACs plus some other hardware; I am *GUESSING* (due to missing images) he used at least 4 chips (based on text): 2 Dual Op-Amps (LM 358s?), a 74LS244 buffer, a 7427 Tri-NOR for "Brown"; and a dozen or so diodes and customized resistors. Without confirmation by text or photo, we really don't know what resistor values!! Does anybody have a full schematic of Richard42's converter? Can you post it for us? Thanks!!!
I think the colors of his and mine compare very well (based on my memory... we seem deprived of photo-comparison). So really, if you agree the quality is the same, it only comes down to which version you think would be cheaper / easier-to-build / or more reliable. He used GBS-8220 for VGA while I used Ambery VGA adapter. I have actually tried both; the quality of the VGA is similar, but the GBS-8220 is known to fail at PAL vertical frequencies; I have no reports about Ambery VGA at PAL frequencies (and I can't test because 1. I sold all the VGA adapters I built, and 2. I only own NTSC Commodore and Monitor).
Although I know my VGA "Ultimate" adapter is great, it would be nice to truly compare it to Richard42's circuit. Based on text (sadly, no images), it seems like he designed a high-quality (ultimate) device too. My design only uses 2 chips (or 3 if you want 12V->5V conversion) and an array of diodes and 2K resistors, while he used at least 4 chips and an array of custom resistors (whose values seem lost to history?).
Anyway, I would like to know more about Richard42's solution (so we all can compare)... so if anybody knows anything (or bought an adapter from him), please let us know. Thanks.
It's a single chip solution (because I used programmable logic) with 7 resistors for the DAC (2 per colour and one for sync).
Awesome! I always wanted to get into programming GALs / PLAs / etc. but never did. Your solution looks really simple (assuming you have the ability to program a GAL). Thanks for sharing! Your circuit board is really tiny and looks WAY more professional than mine. The images you post have great color quality and detail too. Bravo! So I have to admit, your solution is more "high tech", but I think mine gives good results for low-tech Really, I think it is great there are so many options available for all the die-hard C128 enthusiasts!
My only question is... isn't there some "schematic" / "program logic" for the GAL shown on your web page? I didn't find a link on the page you referenced. It seems really useless without that technical detail... So if I (or another C128 user) wanted to build your device, what other data is needed?
Wow, RobertB! You sure are good at finding things buried in the web. Due to the amount of travel you do, I am beginning to think you work for the NSA/MI6/KGB for data mining operations! I am sure will deny this, as a covert government operative must do!
To answer your question, you might create a new thread under C128 (root) / hardware / video, with a title like "Recovered Details of Richard's Video DAC". Of course that is a very nerdy title (call me a nerd), so maybe you can think of something more artistic / poetic ?
However you share it, I think the C128 community would be enlightened (and should be grateful for your "archaeology").