scorp wrote on 2021-02-08, 20:20:

Which by the ways easy to get, I bought two used 1970NX for 10€ each, just couple of weeks ago.

I was talking about the CRTs

maxtherabbit wrote on 2021-02-09, 04:06:

scorp wrote on 2021-02-08, 20:20:

Which by the ways easy to get, I bought two used 1970NX for 10€ each, just couple of weeks ago.

I was talking about the CRTs

Oh, I see. But as far as I know, all the Amiga capable monitors do accept RGBS. Unfortunately, I have none, but I think, that my adapter would make it possible to run the MDA/CGA/EGA PCs with such monitors. Would be nice, if someone would test it 😀

scorp wrote on 2021-02-09, 08:16:

maxtherabbit wrote on 2021-02-09, 04:06:

scorp wrote on 2021-02-08, 20:20:

Which by the ways easy to get, I bought two used 1970NX for 10€ each, just couple of weeks ago.

I was talking about the CRTs

Oh, I see. But as far as I know, all the Amiga capable monitors do accept RGBS. Unfortunately, I have none, but I think, that my adapter would make it possible to run the MDA/CGA/EGA PCs with such monitors. Would be nice, if someone would test it 😀

An OSSC in line doubling mode (to convert 15.7KHz to 31.4KHz , 21.8 kHz to 43.6KHz, etc ) and an HDMI monitor which is tolerant of oddball horizontal scan rates might be interesting complements to your adapter , but OSSC only accepts composite sync through its SCART input .

For example, my current retro monitor (Philips 252B9, which is still sold new) claims the following horizontal frequency ranges are supported :
through HDMI or Displayport : 30 kHz - 96 kHz (a Mac IIvx's 512x384 @ 24.42KHz vertical frequency did not work in passthrough through the OSSC, but using the OSSC to line double to 48.84KHz worked fine)
through VGA (separate sync and sync-on-green are supported but not composite sync or at least not officially, but it would be worth a try) or DVI : 30 kHz - 85 kHz

@darry My adapter can not only composite sync, it also works in HV-Sync mode, where only the colors will be converted to analog RGB.

scorp wrote on 2021-02-09, 09:04:

@darry My adapter can not only composite sync, it also works in HV-Sync mode, where only the colors will be converted to analog RGB.

🤣, I somehow missed the HV sync support option even thoughI watched your MCE-adapter videos. I should have been more attentive.

darry wrote on 2021-02-09, 09:13:

scorp wrote on 2021-02-09, 09:04:

@darry My adapter can not only composite sync, it also works in HV-Sync mode, where only the colors will be converted to analog RGB.

🤣, I somehow missed the HV sync support option even thoughI watched your MCE-adapter videos. I should have been more attentive.

Hehe, such things happen to me all the time as well. I guess, this is the price we pay, if the brain is overrunning with ideas 😁

scorp, if you are referring to the 1084 line of monitors most have a TTL RGB input (meant for the C128 and the commodore pcs) and you can use a straight cable for CGA and LOW-RES EGA.
MDA will not work AFAIK and I have seen posts where people connected EGA cards, switched to high-res 25khz mode and the 1084 fried it self.

The adapter would only be useful with some 1084 models that omit the TTL RGB input I guess - again no 25k modes though so be careful!

Ofcourse there are multisync commodore monitors - they can sync to cga/ega/ega25k/vga with just a cable.

keropi wrote on 2021-02-09, 09:44:

scorp, if you are referring to the 1084 line of monitors most have a TTL RGB input (meant for the C128 and the commodore pcs) an […]
Show full quote

scorp, if you are referring to the 1084 line of monitors most have a TTL RGB input (meant for the C128 and the commodore pcs) and you can use a straight cable for CGA and LOW-RES EGA.
MDA will not work AFAIK and I have seen posts where people connected EGA cards, switched to high-res 25khz mode and the 1084 fried it self.

The adapter would only be useful with some 1084 models that omit the TTL RGB input I guess - again no 25k modes though so be careful!

Ofcourse there are multisync commodore monitors - they can sync to cga/ega/ega25k/vga with just a cable.

Since I never had an Amiga, I'm actually not sure, what I'm referring to. However, there are plenty of reports online, where people connected their Amigas through GBS-8200 to a VGA Monitor. One of the popular examples was RMC on Youtube. Well, the thing is, GBS-8200 can't handle TTL RGB (nor CGA neither EGA, despite, that they advertise this), but needs analog RGBS input signal. Since it worked with Amiga, I just assume, that its output must be analog RGBS, otherwise it would not work with GBS-8200. This leads me to the conclusion, that the CRT monitors, which were used with Amiga back in the days, supported analog RGBS (what is partially the same as SCART). If this is true, then you would be able to connect at least CGA and low-res EGA using my adapter to such a monitor. But this is just a theoretical assumption. If this is true, what you are saying in regards of 25kHz and killed display, then I would call it a really bad design 😁 Would be not the first one in the history....

just to be clear - a "full" 1084 monitor has:
- analog rgb input
- ttl rgb input
- cvbs input
- luma/chroma input

depending on the monitor number it could even have a normal scart connector, or omit the TTL RGB input or omit the luma/chroma one etc...
amigas output analog rgb so you would connect them to the always-present analog-rgb input.

keropi wrote on 2021-02-09, 10:33:

just to be clear - a "full" 1084 monitor has: - analog rgb input - ttl rgb input - cvbs input - luma/chroma input […]
Show full quote

just to be clear - a "full" 1084 monitor has:
- analog rgb input
- ttl rgb input
- cvbs input
- luma/chroma input

depending on the monitor number it could even have a normal scart connector, or omit the TTL RGB input or omit the luma/chroma one etc...
amigas output analog rgb so you would connect them to the always-present analog-rgb input.

I see, thank you! So, what exactly is TTL RGB on that monitor? Which format does it support - CGA, EGA? The thing is, that this digital standards don't only bring RGB, but also intensity signals and such things. The pinout is also different between MDA/Hercules, CGA/EGA and 64-colors EGA. Obviously, you can't connect MDA/Hercules, CGA and EGA to analog RGB. Independent from what TTL RGB on that monitor means, with my adapter you could convert at least the color signals of any of that standards to analog RGB. This should work at least for 15kHz CGA/EGA modes. If the display can manage 18kHz/50Hz, then also MDA/Hercules would work and if it would be able to handle frequencies above 21kHz/60Hz, also high resolution EGA would work.

P.S. And if you have a TV with SCART, my adapter should also make it possible to connect at least CGA/EGA to that TV and if it supports the MDA and high resolution EGA frequencies, also that ones. I think, there are plenty of use cases for this adapter, which would be interesting to test. At least with my NEC LCD1970NX, I can now use any of that graphics adapters and it works flawlessly 😁 On EIZO L365 display, unfortunately, only high resolution EGA works, the other frequencies are not supported 🙁

The TTL RGB input on 1084 monitors is 15khz - so cga and low-res EGA will work. The monitor also does the "brown fix" internally.
Overall the 1084s are 15khz-only monitors - just for encyclopedic reasons there is an extensive list of them here: https://gona.mactar.hu/Commodore/monitor/Comm … del_number.html

I have soldered a similar ttl->analog adapter in the past, you can see it here: Re: Hyundai SUPER-16TE xt clone: restoration and info (home-made vero board mounted in front) and in action here Re: Hyundai SUPER-16TE xt clone: restoration and info
an evolution of this adapter is the "cga2scart" adapter serdashop sells.

Yes, my solution is basically the same as cga2scart, but just slightly more sophisticated. In addition to what cga2scart does, my adapter can also MDA/Hercules in green/white mode, 64-colors EGA and you can select between Composite and HV-Sync.

keropi wrote on 2021-02-09, 11:18:

The TTL RGB input on 1084 monitors is 15khz - so cga and low-res EGA will work. The monitor also does the "brown fix" internally.
Overall the 1084s are 15khz-only monitors - just for encyclopedic reasons there is an extensive list of them here: https://gona.mactar.hu/Commodore/monitor/Comm … del_number.html

Interesting some 1084 monitors didn't support digital RGBi, but only analog RGB. For example such monitors would be subject for testing with my adapter as well. Unfortunately, I can't find any data about supported frequencies in that list, or am I blind?

EDIT: one link from that site gives the information http://www.msxpro.com/mon15khz.html. There seem to be a lot of CRTs, which do support everything between 15kHZ and 31kHz 😀

Your device looks a lot like the one from gglabs, which I have. Though yours have one big advantage for me, which is usb power input! I had to hack a usb cable just to power my CGA2RGB.

Another problem I had was using their adapter on a Scart TV. I don't know if you do it differently, but simply combining H and V to make a composite sync isn't enough for some TVs; I had to hack my cable and use the Composite video output that is thankfully present on my Tandy 1000, and also on some EGA cards. I don't know if this sync problem can be solved easily, but maybe some extra pads and a jumper to select an external sync setting?

[edit] another thing that wasn't present on my adapter, is the ability to pass power to the Scart cable. 5V and maybe 12V are needed to switch the TV into proper RGB mode. VGA pin9 is +5v but is really almost never used. I don't know if you do.

jarreboum wrote on 2021-02-21, 21:04:

Your device looks a lot like the one from gglabs, which I have. Though yours have one big advantage for me, which is usb power input! I had to hack a usb cable just to power my CGA2RGB.

Another problem I had was using their adapter on a Scart TV. I don't know if you do it differently, but simply combining H and V to make a composite sync isn't enough for some TVs; I had to hack my cable and use the Composite video output that is thankfully present on my Tandy 1000, and also on some EGA cards. I don't know if this sync problem can be solved easily, but maybe some extra pads and a jumper to select an external sync setting?

[edit] another thing that wasn't present on my adapter, is the ability to pass power to the Scart cable. 5V and maybe 12V are needed to switch the TV into proper RGB mode. VGA pin9 is +5v but is really almost never used. I don't know if you do.

Yes, just looked at the gglabs solutions, it is very similar indeed. They seem to have an RGB amplifier at the output. My adapter doesn't have it, but at least in my tests, I didn't see a necessity for that one. It makes this adapter more expensive, but may be more monitors would work with it. However, all I tested worked flawlessly without the amplifier as well. Furthermore, I try to do all my DIY with TH components to make it a simple soldering joy for every beginner. And in regards of features, as far as I can see, the solution by gglabs doesn't support 64 colors EGA. My adapter does. May be I overlooked something...

scorp wrote on 2021-02-23, 16:06:

jarreboum wrote on 2021-02-21, 21:04:

Your device looks a lot like the one from gglabs, which I have. Though yours have one big advantage for me, which is usb power input! I had to hack a usb cable just to power my CGA2RGB.

Another problem I had was using their adapter on a Scart TV. I don't know if you do it differently, but simply combining H and V to make a composite sync isn't enough for some TVs; I had to hack my cable and use the Composite video output that is thankfully present on my Tandy 1000, and also on some EGA cards. I don't know if this sync problem can be solved easily, but maybe some extra pads and a jumper to select an external sync setting?

[edit] another thing that wasn't present on my adapter, is the ability to pass power to the Scart cable. 5V and maybe 12V are needed to switch the TV into proper RGB mode. VGA pin9 is +5v but is really almost never used. I don't know if you do.

Yes, just looked at the gglabs solutions, it is very similar indeed. They seem to have an RGB amplifier at the output. My adapter doesn't have it, but at least in my tests, I didn't see a necessity for that one. It makes this adapter more expensive, but may be more monitors would work with it. However, all I tested worked flawlessly without the amplifier as well. Furthermore, I try to do all my DIY with TH components to make it a simple soldering joy for every beginner. And in regards of features, as far as I can see, the solution by gglabs doesn't support 64 colors EGA. My adapter does. May be I overlooked something...

By 64 colors in EGA, do you mean the ability to display 16 colors from the 64 color palette in 200 line mode ?

No, by 64 colors I mean 64 colors. EGA has two modes, RGBI and RGBIrIgIb. The gglabs adapter seems to support only the first one - RGBI. If you connect an EGA graphics adapter in hi-res mode (350 lines) or try to play a game, which supports 64 colors EGA mode in low-res (200 lines), then your colors will be all messed up. There are not many games, which support 64 colors in 200 line mode however. One example would be "Ironman's super offroad racer". However, for 350 line 64 colors EGA mode, there are a lot of examples. Lemmings is a famous one.

Dude, RGBIrIgIb EGA is 16 out of 64, even with those non standard clones that can pull it off in low-res.

Oh! I somehow read it wrong. Sure, 16 out of 64 color pallet. But still, if I understood it right, the gglabs adapter can only RGBI with 16 colors pallet. I might be wrong however, since I don't own one.

tested mce in cga-mode on tandy1000 rl/hd with nec71vm.
it works great. minor issue, textmode and graphicsmode differ up to 5mm to the left.

will check if I can get a smaller image-setting so everything is visible.