OSSC and old PCs

Discussion about old graphics cards, monitors and video related things.

OSSC and old PCs

Postby arncht » 2019-2-09 @ 08:23

Hi

I plan to buy the ossc for my retro pcs. I would like to cover the 90s, dos/windows, but my modern monitor does not have analog input.

It looks fine for the vga input, but i did not find too much information about the higher, and the trickier vesa resolutions. Many demos uses special vesa modes, eg 512×384, 400×300, and i also would like to use for windows with 1024×768.

Can these modes work fine? Thx!
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Re: OSSC and old PCs

Postby root42 » 2019-2-09 @ 09:22

The OSSC is a brilliant device, however it is mostly aimed at consoles. For that the support for PC resolutions is not optimal. I needed quite a bit of fine tuning of the timings to get 720x400 text mode (which includes 640x400 and 320x200 graphics modes) and 640x480 VGA resolutions to work well. But it is possible and the picture quality is excellent. 800x600 also worked great in Windows 3.1. My tests with 1024x768 were not so good, since my Trident card back then only supported interlaced mode. Which works well with consoles outputting interlace, but sharp Windows graphics were not its strong point.

I did a short video on capturing retro PC stuff with the OSSC: https://youtu.be/i_r90B5VG1c

All in all if your monitor does NOT have a VGA in the OSSC is probably the most versatile solution you can get. You can even simply attach a console via RGB or SCART, next to the PC. The OSSC will definitely also do the special modes, albeit you might again need to adjust the detailed timings on the OSSC. The problem might lie on your monitor side, since the OSSC will basically put through the input signal, so it has to be supported by the monitor. You can do 2x or 3x line doubling/tripling, but for some weird resolutions this will not help getting them to a standard resolution. So YMMV with the monitor you use.
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80386DX@25 MHz, 8 MiB RAM, Tseng ET4000 1 MiB, schlae AdLib, PC MIDI Card + SC55MkII, XT CF Lite, OSSC 1.6
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Re: OSSC and old PCs

Postby arncht » 2019-2-09 @ 14:10

is the remote worth the price?
how does it switch between the modes? is it completely manual, or it detects, just you can override it?

i tested just with the nvidia control panel, there is possible to set custom resolution. i dont know, they are "real" output resolutions or not - but many critical resolution worked. i created a table for testing the 2x-4x resolutions with a specific frequency.

https://docs.google.com/spreadsheets/d/ ... sp=sharing
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Re: OSSC and old PCs

Postby root42 » 2019-2-09 @ 14:22

Without the remote the OSSC is tedious to control at best. You need the remote mainly to navigate through the menus or to switch scanlines on or off. But once you have your favourite settings you can save them as presets.
Soldering, retro game reviews and more on YouTube and Bonus videos
Me playing games on my 286 and on my Sega MD2 on Twitch
80386DX@25 MHz, 8 MiB RAM, Tseng ET4000 1 MiB, schlae AdLib, PC MIDI Card + SC55MkII, XT CF Lite, OSSC 1.6
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Re: OSSC and old PCs

Postby arncht » 2019-2-10 @ 06:59

root42 wrote:Without the remote the OSSC is tedious to control at best. You need the remote mainly to navigate through the menus or to switch scanlines on or off. But once you have your favourite settings you can save them as presets.


and do you need for the presets? or it switches automatically between them?
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Re: OSSC and old PCs

Postby root42 » 2019-2-10 @ 09:11

I think you have to switch manually. But mostly one profile will be enough. I think you only need that with multiple devices. The remote also allows you to more easily switch between profiles:

http://junkerhq.net/xrgb/index.php?titl ... te_control
Soldering, retro game reviews and more on YouTube and Bonus videos
Me playing games on my 286 and on my Sega MD2 on Twitch
80386DX@25 MHz, 8 MiB RAM, Tseng ET4000 1 MiB, schlae AdLib, PC MIDI Card + SC55MkII, XT CF Lite, OSSC 1.6
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Re: OSSC and old PCs

Postby SirNickity » 2019-2-11 @ 07:51

For your first one (or only one), get the full package - remote, PSU, etc. It's worth the minor outlay to make it truly functional out of the box.

I have four PCs (386 to Pentium II with Voodoo 5) that only have VGA ports. They all go through a KVM and into the OSSC. You do have to fiddle with the timings to get the screen aligned and sized correctly, but once you get it right, it's smooth sailing. I have each PC saved to its own profile. The 16 profiles will save all the settings from that input, and can either be tied to the input (switching to Video 3 [VGA] in sets it to profile X) or vice versa (loading profile X sets it to Video 3), or they can remain independent. One profile saves settings for each resolution that you've customized.

It detects the resolution well enough most of the time. I've had it guess wrong a couple times, but setting the sync timing a little one way or the other usually gets it right on track. My TV is a little particular about some of the timings, and I've had the OSSC lock to the correct res and the TV still not show a picture. You can sometimes fix this be tweaking the X or Y active area by a few pixels. It gets to be a tiny bit of trial and error combined with a gut sense of what you might have to do to get a particular res working. In the end, my TV has been willing to accept more resolutions through the OSSC sampling VGA than it would from a direct DVI to HDMI feed.

I've done 1270x768 and beyond. Not sure what the highest resolution is that it'll successfully lock to. I want to say I've had it up to 1600x1200, but I could be mistaken. Suffice to say, for vintage VGA-only PCs, it's normally higher than the card can do comfortably and still run games at a reasonable frame rate.

No regrets. I bought it for 240p sources and was THRILLED at how great it work with PCs. But your TV has to cope with 70Hz for those DOS resolutions. The OSSC can, but it won't fix a TV that doesn't.
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