Moe Posted June 23, 2020 Share Posted June 23, 2020 Hey everyone, I just got a Commodore 128 last week, and I also ordered a OSSC about 2 weeks ago (I should receive it in a few weeks, I hope). If I want to run my C128 in 80 column mode I need to use the RGBI output. Can I connect the RBGI port, on the C128, directly to the VGA port on the OSSC? Or do I need to use a CGA2RGB to convert the digital RBGI signal to analog, before feeding it into the OSSC's VGA port? I have seen a few posts about doing this with a GBS-8200, but none using a OSSC. Any information you might have will be greatly appreciated. Cheers, Moe Quote Link to comment Share on other sites More sharing options...
carlsson Posted June 24, 2020 Share Posted June 24, 2020 The RGBI uses TTL levels (nominally 5V, I believe). All documentation about the OSSC warns from connecting such signals directly, so you need a converter to make it analog RGB. I don't know about the CGA2RGB specifically, but if you are into soldering it is relatively easy to build a voltage divider per one of the SCART schematics online. Quote Link to comment Share on other sites More sharing options...
Moe Posted June 30, 2020 Author Share Posted June 30, 2020 Thanks for the info! The CGA2RGB can convert from RGBI to RGBs (https://gglabs.us/node/2063), and the OSSC can accept an RGBs signal. I order a CGA2RGB to test with my C128 and OSSC. Once I receive the CGA2RGB I'll update this topic with my results. Cheers, Moe Quote Link to comment Share on other sites More sharing options...
djc6 Posted August 22, 2020 Share Posted August 22, 2020 On 6/30/2020 at 2:06 PM, Moe said: Thanks for the info! The CGA2RGB can convert from RGBI to RGBs (https://gglabs.us/node/2063), and the OSSC can accept an RGBs signal. I order a CGA2RGB to test with my C128 and OSSC. Once I receive the CGA2RGB I'll update this topic with my results. Moe, what was the final verdict? I'm trying to attempt the same - CGA2RGBv2 / OSSC / C128 in 80-column mode. Any settings you had to tweak on the OSSC? Thanks! Quote Link to comment Share on other sites More sharing options...
Moe Posted August 25, 2020 Author Share Posted August 25, 2020 On 8/22/2020 at 11:31 AM, djc6 said: Moe, what was the final verdict? I'm trying to attempt the same - CGA2RGBv2 / OSSC / C128 in 80-column mode. Any settings you had to tweak on the OSSC? Thanks! Thanks for asking, it forced me to get back to it! Yes, I was able to get 80 column mode working with the CGA2RGBv2 & OSSC. CGA2RGBv2 DIP1 to DIP4 = off Jumper J4 - pin 2-3 I created a USB 5V power cable to power the CGA2RGBv2, since the OSSC does not provide the power. OSSC AV3 - RGBHV Cheers, Moe Quote Link to comment Share on other sites More sharing options...
djc6 Posted September 8, 2020 Share Posted September 8, 2020 (edited) I was able to dramatically improve the picture of the CGA2RGBv2 & OSSC combination by doing a deep dive into the OSSC settings with help from VGP forum: https://videogameperfection.com/forums/topic/commodore-128-cga2rgbv2/ Attached are some photos - it looks a lot better in person, for example none of the color fringing in the GEOS128 photo is present in person. Settings I am using: 240p / Line2x H. samplerate 1016 H. synclen 20 H. backporch 241 H. active 640 V. synclen 3 V. backport 36 V. active 200 Sampling Phase 11 degrees Edited September 8, 2020 by djc6 2 Quote Link to comment Share on other sites More sharing options...
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