The definitive using an MSX with a VGA monitor thread

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By mfeingol

Champion (293)

mfeingol's picture

15-04-2004, 07:09

I've seen this issue come up a couple of times in this forum, but I've never seen a definitive answer regarding the best way to use an MSX computer with a modern VGA monitor.

To begin, a sprinkling of facts:

  • Some people have an MSX with S-Video, and they like it.
  • Some people use RGB to SCART cables, and they like it.
  • Some people have 15 kHz monitors, and they like them.

However, my situation is that I don't like to stare at blurry RCA video on a television, and I have a very nice VGA monitor with two connectors. In an ideal world, my MSX would have VGA out in addition to RGB out and I'd just plug it into the second connector. However, the MSX can't output at 31kHz, and my monitor can't handle a 15kHz interlaced signal.

So I have two options:

  • Use a cheap TV card on my PC and pipe the MSX's RCA out into the card.
  • Get a scan doubler, like the XRGB2+.

I tried a TV card the other day, specifically an MSI TV @nywhere, and the A/V quality was incredibly poor. The edges were blurry, there were artifacts all over the screen and the audio was distorted. I tried direct line-in on the audio, which helped, but there was no fixing the eye-bleeding image quality. Needless to say, I returned the card the next day.

I'm thinking about pursuing the scan doubler option, but it's a difficult area to investigate because of the cost. What I was hoping to learn is whether others here have attempted such a thing, and whether it was worth the expense. I've seen Snout mention that he used a DISPL, but AFAICT he's never really given a thumbs-up or down with respect to image quality. Has anyone here been satisfied or unsatisfied by this kind of solution?

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By [D-Tail]

Ascended (8259)

[D-Tail]'s picture

15-04-2004, 07:52

I don't really know, I use RGB to SCART cables, and I am happy with it ^^;

But I don't think it's as easy as 'make a scan doubler'. I recall MSX-NBNO had such kind of thing. Last fair in Oss they used TFT monitors together with SVHS cables, but they had some kind of device that took care of the conversion of the RGB to the VGA signal. According to them, it wasn't as easy as putting a scan doubler between them.

But I could be wrong... Smile

By anonymous

incognito ergo sum (116)

anonymous's picture

15-04-2004, 13:49

Really? A lot of TFT monitors actually accept 15kHz...
Using a CGA monitor and constructing a RGB cable for that will get you better image quality than RCA video on a TV.
The dotpitch on modern VGA monitors is way too small for low-res graphics anyhow.

By Guillian

Prophet (3502)

Guillian's picture

15-04-2004, 15:25

I use a Pinnacle PCTV conected to my turbo R using S-Video, and I get a perfect image quality on my TFT monitor.
Then, I can take nice screenshots or video captures Wink

By Grauw

Ascended (10581)

Grauw's picture

15-04-2004, 18:46

A while ago, I read up a little on this subject concerning connecting a DVD player to a beamer through RGB... What I recall is that a VGA connector basically consists out of an R, G, B, horizontal sync and vertical sync signal. Fyi, SCART has R, G, B and a composite sync+video signal.

The problem which concerns the need for a scan doubler is the horizontal sync signal, an MSX indeed outputs at 15kHz while the common VGA frequency is 31kHz. Apparantly beamers e.d. generally support lower frequencies like 15kHz quite well - PC monitors do not however (or so I read).

About the vertical sync signal - some types of beamers accept the sync signals right from the composite output, sometimes even not needing a seperate hsync signal anymore, in other cases it has to be 'cleaned' and seperated (iirc not an expensive circuit, tho).

Anyways, seems that it's not exact science that we're talking about Smile. You can try to output a 15kHz signal to your monitor, and see whether it might work. On the other hand - it might break it. You never know. I have a little more faith in trying this out with LCD screens though Smile. Might very well be that they have a better tolerance for lower frequencies, as Guyver said, because they themselves already operate on a lower frequency than most common CRT monitors, and also because the technology processing the signal is very different from CRT monitors (it translates the signal to a digital one instead of letting it drive an electron beam like CRT's do). And, if I'm not mistaking, beamers also utilize LCD technology.


By [D-Tail]

Ascended (8259)

[D-Tail]'s picture

15-04-2004, 22:49

Well, what I actually meant with that TFT/S-VHS thing and that kind of scary device, those were independent things. Last fair in Oss, NBNO had two sets of computers (A1GT) connected with TFT monitors using S-VHS cables.
Way before that, I think it even was 1999 or so, NBNO did a similar trick, but then with a HUGE adapter print which converted the RGB signal to VGA, thus enabling connectivity with a VGA monitor.
So it actually were seperate things ^^;
ma bad Tongue

Concerning your question, mfeingol, you'd better try it with a TFT monitor with S-VHS cables (provided your computer has some kind of S-VHS out (don't use SCART to S-VHS though, quality is poorer than poor!) and the TFT has a S-VHS in).
But I think you'd pose specific questions at MSX-NBNO, you'd probably be better off there. They did the trick, at least Wink

By mfeingol

Champion (293)

mfeingol's picture

15-04-2004, 23:23

I didn't see any information about those devices on NBNO's website or forums, but I will probably ask them about it. Do you know if their projects were intended as a demo, or for production?

CGA monitors do accept 15 kHz signals, but they have the same problem that Grauw mentioned - separate HSync and VSync signals that would need to be separated from an MSX's RGB CSync signal. I suspect that same issue applies to all "VGA" CRTs or LCDs that accept 15 kHz signals.

My own MSX (an FS-A1WX) is not blessed with an S-Video signal - I'm stuck with either the RCA composite cable, which has proven itself to be unacceptably lame, or the RGB out. I have no doubt that S-Video is good enough for most people, especially if they have a nice TV.

Therefore, I don't see too many options except:

1) Find an old Commodore or MSX monitor, and make/find a cable that will connect to the Japanese RGB out.
2) Go the scan doubler route.

I see the second option as more sustainable in the long run, because at some point it will become hard to find working 80's monitors in good condition. That's why I'm very interested in hearing people's experiences with such devices.

By snout

Ascended (15187)

snout's picture

15-04-2004, 23:27

I indeed own and use the DISPL upscan convertor. It gives nice image quality, I was actually qutie surprised of the image quality when I hooked up my GFX9000. However, the newer XRGB 1, 2 and 2+ (hmm.. that naming reminds me of something) surpass the DISPL at any level. I think you will surely enjoy either one of those upscan convertors. There are quite some reviews about 'em on the web, by the way...

By mfeingol

Champion (293)

mfeingol's picture

15-04-2004, 23:35

Thanks, Snout.

Would you say that the DISPL gives you comparable or better image quality than you would get from, say, a 50 or 60Hz Philips MSX monitor using an RGB to SCART cable? What VGA resolutions/refresh rate does the converter generate? Is the aspect ratio correct? Does the DISPL provide an option for scanlines, or blurring?

By snout

Ascended (15187)

snout's picture

15-04-2004, 23:39

The image quality of a DISPL can't be compared to an MSX Monitor. An MSX monitor is small and blurry with 'round' pixels. in MSX-DOS, it feels like you're working on VGA all of a sudden. (See: MSX Emulators). The DISPL has a 640x480 output, 50 or 60 Hz. I never checked the aspect ratio, but it looked fine to me. No extra options for scanlines or blurring, just a brightness controller, and red, green and blue drive controllers. In my case (but I think that's because it's an OLD, rugged device) these controllers have to be set very carefully to create a good image, otherwise there are vertical stripes on the screen.

So, my advise: at least get an XRGB-1.

By karloch

Prophet (2157)

karloch's picture

15-04-2004, 23:44

I'm connecting my MSX to the TV card of my PC (Avermedia TV Studio) using S-Video and the image quality that I get is really nice (TFT Monitor). You can take a look at some screenshots here.

The only problem is that I have to boot up the OS of the PC in order to use the MSX. If you wanna to have your MSX fully independet, you should get the XRGB.

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