15 kHz= 'scanlines'?

Started by zedrein, July 04, 2009, 08:47:16 AM

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zedrein

I've noticed that often times a CRT display that can sync with a 15 kHz source isn't always standard definition (480 vertical lines of resolution) sometimes their resolution is well over 600-1,000 lines of vertical res. My question is: Will the darkened scanlines that are present on 480-line displays (when displaying a 240 line or so image) still be on those high resolution displays as well?

Sometimes I will observe threads saying that any CRT display that can accept that 15 kHz sync signal is suitable for classic gaming in RGB, but if there is no darkened scanlines present to soften the image up, I'd think that would be a good reason NOT to invest in those high res monitors for most people.

Maybe it's important to make a distinction between 15 kHz displays that are high res and standard res for classic gaming needs?

RGB32E

#1
Quote from: zedrein on July 04, 2009, 08:47:16 AM
I've noticed that often times a CRT display that can sync with a 15 kHz source isn't always standard definition (480 vertical lines of resolution) sometimes their resolution is well over 600-1,000 lines of vertical res. My question is: Will the darkened scanlines that are present on 480-line displays (when displaying a 240 line or so image) still be on those high resolution displays as well?

In my experience, the answer is yes!  I had a NEC XM29 (accepts 15kHz-XGA) for a while and it displayed "scanlines" from 240p RGB sources just like a interlaced monitor would.  Hence, if you acquire a large multisync monitor, your experience shouldn't be any different than a monitor that doesn't accept progressive RGB (ie. VGA and above).  Hence, this holds true for the NEC and Mitsubishi multisync presentation monitors...  Unfortunately Sony didn't make any large multisync PVM monitors...  :-\

However, there have been others on this forum that have mentioned that there are discrepencies with certain newer arcade tubes (I believe the D series from Wells Gardner and the like).

Additional Comment:
While the larger multisync monitors do display scanlines with 240p RGB signals, they typically have a higher density of phosphors (so that high resolutions can be resolved)... so it isn't exactly the same as lower resolution cousins...  the net result is very similar though.  If the large CRT isn't a multisync and uses a processor to convert the low-res signals to something progressive (>=VGA), then the answer is no!

Multisync is the keyword here...  :P  :D

zedrein

That's delightful to know. I for one wouldn't want to experience my oldies with no scanlines anyway.

Thanks for the first-hand experience!

NFG

You're confused, zedrein.  a 'scan line' is simply the gap between the illuminated phosphors.  On a higher resolution screen the beam is narrower (more vertical pixels = narrower beam to pack 'em all in) and therefore the gap simply becomes larger.  Unless you're upscanning the low-res source, the high-res screen will not fill in those gaps.

So, ultimately, a high-res screen won't be the same for 15kHz gaming as a low-res screen, but it'll still be better than a scaled/interpolated LCD screen showing the same signal.

zedrein

#4
I suppose I should of asked, "Will a high-res 15 kHz CRT screen upscale a low res image in a way that will remove all my precious scanlines?"

But thanks for the reply. I am actually happy to know that they won't because in my opinion the less weird re-sampling, especially common among modern displays, the better. Here's another barb for ya: Mr. RGB said that these higher resolution 15 kHz CRT displays will actually yield "very similar results" to a standard resolution display even with all of the additional stretching, and you just commented that "A high res screen won't be the same..." In all y'alls opinion, is this difference negligible or can it be considerably annoying?

On a different {and quite frankly masochistic} note, is there anyway possible a person could somehow force a common VGA display to display a source in 15 kHz? I would wager not, but for curiosities sake I had to ask.

Thanks for your time!

zedrein

#5
UPDATE: I was cleaning about my apartment today when I noticed a little gem: A 19 inch KDS "Multi-Scan" CRT display! It has two inputs: VGA {15-pin D-sub} and 5 BNC connectors! {R G B H V} It was manufactured in April 1999 and is most certainly a high resolution unit. I only have my PC connected to it now {via D-sub VGA} which is scanning at a 59 Hz (vertical) and 63.9 kHz (horizontal). My God, I really don't know if this thing can do 15 kHz but I surely hope so. Isn't there a software that will add 15 kHz resolutions to my PC? This is surely an exciting day!

Fudoh

Soft15khz - just google for it. Very easy to use.

But chances are slim to nil that your old PC monitor accepts 15khz. There were only very few PC monitors which were able to do it.

kendrick

There's a pretty good reference for VGA monitors that can do 15 kHz synch here:

http://www.best-electronics-ca.com/monadapt.htm

It looks like a long list, but you have to remember that there have been literally thousands and thousands of makes and models. Unfortunately, KDS monitors don't appear anywhere on the list. BNC connectors usually mean that the monitor was used with Sun computing equipment, since many Solaris machines used plain old BNC video output. It was still 24 kHz output or higher though.

zedrein

I'm starting to think this thing can't do 15 kHz. Why, God, why?