February 16, 2018 at 9:39 AM #19339
In case anyone wonders how the OSSC handles a retro PC with VGA only output…
I’m in tears of joy, god bless you marqs.
It does 640×400 (native DOS and 99.999% games) and 640×480 marvelously!!!
640×400 runs in 384p Line2x mode but I adjusted V.Active to 480 so my screen shows it in 4:3 (1280×864),,,
In 384p (640×400) Line2x mode the result is super sharp and smooth 70Hz, just like a quality PC CRT from back then would but on a modern LCD with HDMI.
Yes, the screen has VGA input but the OSSC looks MUCH sharper in Line2x mode, as it would on a CRT.
Did I say the OSSC is great already? 🙂
February 16, 2018 at 10:28 AM #19342
Nice, I was meaning to test this more thoroughly. My TV won’t do the 70hz modes sadly (that’s to be expected).February 16, 2018 at 11:06 AM #19345
Although, it would be ideal to have 640×400 and 720×400 70Hz (449p) modes for PC RGBHV, because 384p is somewhat dodgy and requires extensive advanced timing tweaks, I don’t think it was meant for PC input anyway.
Marqs you there?
Proper 640×400 mode was added to firmware v0.81.July 25, 2018 at 6:23 AM #22588
Here are my advanced timing setting for 400 mode for retro PCs with OSSC firmware v0.81.
This will result in no overscan and will show in perfect 4:3 on a PC monitor (not TV) with HDMI input.
Note that 400p mode is 70Hz and TV don’t like that at all, but PC monitors do.
480p in sampler: VESA 640×480@60
Allow upsample2x: On
384p proc: Line2x
480p/576p proc: Line2x
TX mode: DVI
640×400 (PC mode)
H. Samplerate : 700
H. Synclength : 62
H. Backporch : 54
H. Active : 576
V. Synclength : 2
V. Backporch : 18
V. Active : 432July 25, 2018 at 4:27 PM #22594
Do these settings change for higher resolutions (800 x 600 or 1024 x 768)?
Can this work in 60Hz to use on an HDTV?July 25, 2018 at 10:43 PM #22601
Thank you for posting the screenshots. I see people using these old school PC’s with the OSSC, and am always interested in what is being played. Congrats, looks great!July 26, 2018 at 9:16 AM #22603
Can this work in 60Hz to use on an HDTV?
The OSSC does not change refresh rate, what comes in is what comes out.
I don’t think an HDTV will take 70Hz resolutions, so it’s mainly for modern PC monitors.
I may be wrong so give it a try.July 28, 2018 at 9:14 PM #22633
So I tried your timings, but they lead to no sync at all when in text mode. Since the DOS text mode is also 400 lines, I do not see an option to use those settings, apart from loading a preset when running a game, which I find inconvenient. I use these settings in VGA text mode (720×400@70 Hz) on my 286 PC (currently with Trident 9000, but also with ET4000):
H. samplerate 874
H. synclen 104
H. backporch 51
H. active 741
V. synclen 2
V. backporch 32
V. active 405
This is obviously the same settings that is used for 320×200 games under DOS.
Windows runs in 640×480@60 Hz using these timings:
H. samplerate 850
H. synclen 59
H. backporch 56
H. active 720
V. synclen 2
V. backporch 30
V. active 480
This leads to a good picture, although 2 lines or so at the bottom are missing. But so far I am not bothered.July 28, 2018 at 9:45 PM #22634
Interesting enough, using Line2X makes the 480 mode worse. See the screenshots below for an example. Both screenshots are shot with reset settings in 640×480@60 Hz:
And with Line2x disabled, but DTVP sampler I get this (it has some noise, black and white edges are flickery), it at least shows the whole screen:July 29, 2018 at 6:45 AM #22639
So I tried your timings, but they lead to no sync at all when in text mode.
These settings work perfectly well on all my LCD PC monitors in text mode 720×400@70Hz as you can see on the first post of this thread, playing Doom (320×200) and Norton Commander (640×400).
I do not see any artifacts nor the corners cut off (no overscan).
Note that the resulting resolution will be 1152×864 (XGA+) with 384p Line2x which is in a VESA standard and works on all PC Monitors, but when not using Line2x the base 576×432 resolution is NOT part of the VESA standard.
You can raise H.Samplerate if you have overscan and recenter with Backporch and/or Synclength.
With 640×480@60Hz (320×240) modes, I see no artifacts nor overscan.
Note that when using upsample2x you should always use Line2x for 480p modes since upsampling requires higher resolution to not look jaggy.
Remember that using Line2x for 480p will output 960p, that PC monitors love, but TV’s hate.
What PC monitor are you using?
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