MiST and RGB Output

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rittwage
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MiST and RGB Output

Postby rittwage » Wed Sep 14, 2016 7:14 pm

I just ordered a MiST. Previously I have owned a Chameleon, so I hope this is a similar device with even more core support! :)

Anyway, I noticed there is an SCART adapter and many cores support 15Khz output. I am in NTSC land- can I buy or make a cable that would work with my Sony PVM monitor? I can find cables with VGA to 5xBNC connectors on eBay, but don't know if the wiring would be right... Would I have to make my own custom cable - and does this even work well?

-Pete

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Re: MiST and RGB Output

Postby rittwage » Wed Sep 14, 2016 7:15 pm

Sorry for the multiple posts. The server returned an error when I submitted, so I figured it wasn't working.

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Re: MiST and RGB Output

Postby ijor » Wed Sep 14, 2016 9:35 pm

Hi Pete,

The MIST VGA is a standard VGA connector. I'm not familiar with that Sony monitor, but any adapter that is designed for standard VGA should work. And any old VGA monitor that supports 15kHz works out of the box with a regular VGA cable.

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Re: MiST and RGB Output

Postby rittwage » Wed Sep 14, 2016 10:40 pm

The Sony monitor has 4 BNC inputs for RGB- R, G, B, and Sync. There are cables on eBay with 3, and some with 5. I guess I will grab one with 5 and maybe I'll get lucky- unless the pinout on the MiST is special/non-standard.

Does the "standard" VGA pinut have a pin for CSYNC, or just separate HSYNC and VSYNC?

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Re: MiST and RGB Output

Postby Newsdee » Wed Sep 14, 2016 10:53 pm

Standard VGA has separate HSYNC and VSYNC at 31khz. I don't recall if the 15khz mode outputs CSYNC instead of HSYNC, but it ought to be compatible since people are using it with SCART TVs.

Just watch out not to run a 31khz mode.with the PVM. It's fine on my XRGB-mini using a sync combiner, but not sure if the PVM will like the frequency.

I have a BNC cable but didn't get a PVM yet. :) Tempted but they aren't cheap around me. Also I dont really have the room. :(
Last edited by Newsdee on Thu Sep 15, 2016 12:07 am, edited 1 time in total.

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Re: MiST and RGB Output

Postby rittwage » Wed Sep 14, 2016 11:24 pm

I'll give it a shot and report back. Just need a switchbox now...

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Re: MiST and RGB Output

Postby ijor » Thu Sep 15, 2016 2:45 am

Newsdee is right. I checked the Atari cores. They both output CSYNC at the HSYNC pin when configured for 15kHz. (Which means it won't work with old VGA or Atari RGB monitors, as I thought it would).

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Re: MiST and RGB Output

Postby Newsdee » Thu Sep 15, 2016 3:15 am

it's all configurable at core level... maybe we need an INI setting to say if we want CSYNC or HSYNC/VSYNC when the scandoubler is disabled

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Re: MiST and RGB Output

Postby Doozer » Thu Sep 15, 2016 9:30 am

Newsdee wrote:it's all configurable at core level... maybe we need an INI setting to say if we want CSYNC or HSYNC/VSYNC when the scandoubler is disabled


I would also love to see such feature coming to all cores because some arcade monitors have separated H and V inputs and not all accept CSYNC on H input. Currently, you need to use a LM1881 sync separator circuit to process the CSYNC to H/V.

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Re: MiST and RGB Output

Postby ijor » Thu Sep 15, 2016 11:25 am

Yeah, I know the cores can make it configurable. I was going to say that possible not worth, most people don't use old RGB/VGA monitors, but Doozer response shows is not that uncommon :)

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Re: MiST and RGB Output

Postby goev » Thu Sep 15, 2016 11:29 am

I recently made a cable to connect the MiST to a Nec Multisync II and it worked like a charm. I do have a pretty old ST core running, so don't know if anything have changed lately, but it works with my monitor at least.

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Re: MiST and RGB Output

Postby rittwage » Fri Sep 23, 2016 12:40 am

The verdict: It works perfectly. I put the scandoubler line to disable it in mist.ini and hooked up the VGA->5xBNC and it comes up perfectly. I haven't tried all the cores yet, but fpga64 works so far...\

EDIT: Unfortunately not all cores support it... about half and half.

Most notably, Atari 800 and Apple II core do not work in 15khz.

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Re: MiST and RGB Output

Postby RobertK » Sat Sep 24, 2016 8:08 pm

rittwage wrote:Most notably, Atari 800 and Apple II core do not work in 15khz.

The Atari 800 and 5200 cores do support 15 kHz, but instead of adjusting the mist.ini file, you have to use a specific version of the core that is set to 15 kHz. You can find it in the "build_PAL_RGB" or "build_NTSC_RGB" directories on http://www.scrameta.net/autobuild/.

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Re: MiST and RGB Output

Postby ijor » Sun Sep 25, 2016 1:22 pm

Just out of curiosity, what's wrong with scandoubler mode? Doesn't "feel" the same as using 15 kHz on an old CRT monitor? Or is it for 50Hz/PAL, that most newer monitors don't support?

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Re: MiST and RGB Output

Postby rittwage » Tue Sep 27, 2016 8:42 pm

RobertK wrote:
rittwage wrote:Most notably, Atari 800 and Apple II core do not work in 15khz.

The Atari 800 and 5200 cores do support 15 kHz, but instead of adjusting the mist.ini file, you have to use a specific version of the core that is set to 15 kHz. You can find it in the "build_PAL_RGB" or "build_NTSC_RGB" directories on http://www.scrameta.net/autobuild/.


Thanks very much - I will try it out.

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Re: MiST and RGB Output

Postby rittwage » Tue Sep 27, 2016 8:50 pm

ijor wrote:Just out of curiosity, what's wrong with scandoubler mode? Doesn't "feel" the same as using 15 kHz on an old CRT monitor? Or is it for 50Hz/PAL, that most newer monitors don't support?


Yes, it's not the same. Generally scan lines are part of the look of the original hardware.

At 240p (15KHz) every other line is drawn twice every frame, at 60Hz. At 480p (VGA) "scanline" modes just turn off every other line, sending it once every other frame, making it darker, and technically only 30Hz- at least when displayed on an NTSC television.

VGA is of course higher scan rate and progressive, but the video is darker when you turn off every other line. That's why some of the cores have 25%, 50%, 75% scan lines.

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Re: MiST and RGB Output

Postby retrorepair » Tue Sep 27, 2016 11:55 pm

To be honest for me it's the authenticity of playing on an old TV as well as the fact that I use one in my setup of many game consoles so would be tedious to trot out a VGA monitor every time I wanted to use the MIST.

Some games take full advantage of the way old CRTs work as well to draw certain effects. Not to mention the fact on a CRT you can output the video at the exact correct refresh rate which is impossible on a VGA monitor.

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Re: MiST and RGB Output

Postby ericgus » Wed Sep 28, 2016 1:01 am

Nothing worse than "fake" scan lines on an LCD.. scanlines on an original CRT is fine, great even.. but for some reason the "fake" scan lines/filters people employ on emulators and such just seem to induce migraines and blurry vision for me and many people I know as well. Given the option on an LCD display (aka non crt) I always turn off those fake effects.

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Re: MiST and RGB Output

Postby rittwage » Wed Sep 28, 2016 12:27 pm

Atari core compiled for RGB does work and looks beautiful. Now to get the Apple II core in RGB. I was able to git clone the source, but don't know enough about VHDL yet to make modifications like this yet.

I did also try the NES core in RGB- looks great. The PCEngine core doesn't seem to work right in RGB- it rolls like it's doing separate H and V sync instead of CSYNC.

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Re: MiST and RGB Output

Postby RobertK » Wed Sep 28, 2016 2:16 pm

retrorepair wrote:To be honest for me it's the authenticity of playing on an old TV.

Exactly. Here you see what we are talking about. My MIST (outside the picture) connected to a small CRT TV via SCART, running the C64 core.

2016-09-06_MIST_TV_via_SCART_800px.jpg

Those of you who don't have an old CRT TV anymore should try to get one as long as they are still widely available. Just ask all your friends, they might still have one in their basement and will be glad to get rid of it.

rittwage wrote:I was able to git clone the source, but don't know enough about VHDL yet to make modifications like this yet.

Same here. It seems to require only a few lines of code (I had a look at the Spectrum core), but as a complete newcomer to VHDL I was quite hopeless...
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Re: MiST and RGB Output

Postby rittwage » Sun Oct 02, 2016 5:46 pm

It actually has the scandoubler_disable defined in user_io.v, but I don't think it's referenced anywhere.

I can't find what but_sw[4] actually is mapped to...

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Re: MiST and RGB Output

Postby RobertK » Sat Feb 04, 2017 2:55 pm

Discussion from the NES core on MiST thread continued here.

mahen wrote:Hi everyone ! I have a little issue ! For the first time I'm trying the NES core with a 15 KHz screen. An old TV from my wife's teenager bedroom :)
I'm quite happy with the result !

However, NES games (both in PAL and NTSC mode) appear quite off-centered, and especially quite a few columns are missing on the left as you can see here : https://postimg.org/image/urw5d5h1b/ (yes pics are awful, I have an old phone :)


I have exactly the same problem on my 36cm TV (bought in the early 2000s):
2017-02-02_MIST_TV_via_SCART_NES_01_800px.jpg

And it seems that on this TV the picture of most cores via SCART is a little off-centered to the left. On those systems that have a thick screen border (like the C64 or the Spectrum) this is no problem, but for others it is: for example, on the new PET core you see "EADY." instead of "READY.".

Two posts above you see a photo of the C64 core on that TV, showing that the picture is a little too far to the left. But on my 72cm Panasonic TV (bought in 2004) the MIST's picture running the C64 core is well-centered:
2016-12-28_MIST_TV_via_SCART_C64_800px.jpg

So it seems that not all TVs are affected.

The Atari ST core allows adjusting the X and Y position of the screen. With X set to the maximum value of 100, the picture is centered. It would be great if this function could be added to other cores as well.

sebdel wrote:I think on these old monitor you have a setting to manually adjust the position and size of the image.

We are not talking about monitors, but about old TV sets with a SCART connector, and to my knowledge no CRT TV allowed the user any adjustments to the picture size or position. Only if you were a TV technician you could open it and make some adjustments inside, but - as a TV technician told me a few years ago - to a more limited extent than the adjustments possible on a CRT computer monitor.
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Re: MiST and RGB Output

Postby Sorgelig » Sat Feb 04, 2017 3:18 pm

try this version.
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Re: MiST and RGB Output

Postby RobertK » Sat Feb 04, 2017 6:55 pm

Thanks, but unfortunately I don't notice any difference. :shrug:

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Re: MiST and RGB Output

Postby jaildesigner » Mon Feb 06, 2017 7:51 am

rittwage wrote:I just ordered a MiST. Previously I have owned a Chameleon, so I hope this is a similar device with even more core support! :)

Anyway, I noticed there is an SCART adapter and many cores support 15Khz output. I am in NTSC land- can I buy or make a cable that would work with my Sony PVM monitor? I can find cables with VGA to 5xBNC connectors on eBay, but don't know if the wiring would be right... Would I have to make my own custom cable - and does this even work well?

-Pete


I do not know if I'm too late, but that's the setup I'm using and it works like a charm. Mist RGB is like any other RGB signal, so you can connect it to the PVM like you do with the SuperFamicom, MegaDrive, etc..


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