Can you get a better 80-column picture?

martona · Newbie Joined: 06 Mar 2012 Posts: 27

On a modern, HDMI or VGA monitor, that is.

This is what I use:

http://www.ambery.com/rgbcgatovgac.html

This gives me a plain VGA (XGA) signal that I hooked up to a HP monitor.

And this is what I get:

http://i.imgur.com/nNtQs.jpg

Clearly not the best. Any thoughts?

eslapion · Posted: Thu Apr 05, 2012 2:55 pm Post subject:

The Ambery can convert to VGA of different resolution.

I suppose when you say (XGA), this means you set it to 1024x768, correct?

Since the Ambery can also convert from other types of sources, have you tried using it with RGB signal such as from an Amiga computer?

AFAIK, tha Ambery requires analog RGB signal while the C128 provides digital RGBi. How are you converting from digital RGBi to analog RGB? Maybe the problem is with this first conversion.
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martona · Newbie Joined: 06 Mar 2012 Posts: 27

Thanks... you may be right about the digital vs. analog problem. I'm not doing any conversion, I'm just using the Ambery CGA-to-15-pin cable that I got from them to connect the C128's 9-pin output to the Ambery's input. But Ambery specifically says their product is meant to work with CGA, and CGA is digital, right? In fact, I thought it was identical to the C128 output.

I haven't tried it with other video sources, simply because I don't have a cable for, say, the Amiga. I ordered a 23-pin-to-9-pin from Amigakit, it seems to have the right pinout, but it's not here yet and even if it were I'd probably have male/female issues with it.

Do I have any good options for the C128, other than using a vintage Commodore monitor?

tokra · Newbie Joined: 18 Feb 2011 Posts: 18

This is what you're looking for:

http://www.commodore128.org/in...2#msg19942

Sadly Richard42 sold all he built of those, but he posted instructions and diagrams so someone else should be able to build those again.

Basically this device converts the C128-digital-RGBI with 16 colors to an analogue RGB-signal which can be fed into converters like the GBS-8220 or the Ambery you own.

I own both the Ambery and GBS-8220 and before this small device came around connected the Ambery just like you did. Two problems:

- Signal levels are 5V when they should be 0,7V. Doing this may damage your hardware (so I've heard).
- you only get 8 colors because the I of the RGBI-signal is not converted.

The Ambery as well as the GBS-8220 claim to be "CGA"-converters, when in fact they are not. Sadly some time during the late 80s somehow the real meaning of CGA got lost and was used for arcade-machines monitors, which are in fact RGB analogue (like the Amiga). So in order to convert "true" digital CGA (= RGBI) you need the small device or some similar solution like this one:

http://sites.google.com/site/h...bi-s-video

I much prefer the GBS-8220 solution though. This produces a picture a lot better than the Ambery even with the RGBI->RGBA converter. Mine works with 50Hz as well. Also the GBS-8220 can be found on Ebay for about only $30-$40.

martona · Newbie Joined: 06 Mar 2012 Posts: 27

Thanks for the thorough explanation!

adric22

martona wrote:

On a modern, HDMI or VGA monitor, that is.

This is what I use:

This is just a curiosity. What do you actually intend on using the 80-column display for? I actually sold my 128 years ago because I just had no use for it. All of the software that runs on 80 columns was essentially productivity software, which I now use a more modern computer for. Everything else I wanted to run was C64 software.

dabone · Posted: Sun Apr 08, 2012 2:20 am Post subject:

I've got one of the RGBI to RGBA boards from Richard42, but I ran it thru a rgb to svideo convert from amigamaniac. It works for text mode on both my 15" and 20" lcd tvs, but the 20" won't display the risen demo (Out of sync I guess.).

This solution looks alot better than the pic you have posted, and allows me to have a single modern display for both the composite and rgb outputs without resorting to a scan converter.

Later,
dabone