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Upscalers vs. Atari ST - OSSC, OSSC Pro & RetroTink 5X


I had a question from a supporter about the Atari ST and the new OSSC (Open Source Scan Converter) Pro. So I decided I may as well try it out with all of my scalers!


Hey everyone and welcome back to the second channel, hope you’re all doing well, and yes, in the quite recent past a video has gone out on my main channel, and I’m not 100% sure on the timing of all of this, so it’s going to be vague, but a video went out covering the OSSC Pro - which is this white box you see on the desk here, and this is an upscaler.

What it does is it takes a signal from these lovely old computers and games consoles, and it upscales them, or it line multiplies them - whichever mode it’s in - and basically it converts it into a higher resolution and refresh rates which are compatible with modern displays.

So of course we don’t need to use those old CRTs and things like that.

And I’m particularly interested as a YouTuber - I’m particularly interested in capturing the video from these old machines. Rather than actually playing on these displays I tend to split the signal and use an actual CRT and then upscale that and capture that as a separate thing.

I can’t play games through my capture device directly because it introduces too much lag, which thankfully the OSSC doesn’t.

And on the note of lag I must say that is something that I didn’t cover in the video for a few reasons: one being because my use case is predominantly as a YouTuber, wanting to split the signal and capture the video, so the lag’s not really that important to me.

The other reason being that I’m not really qualified to measure that, and there are channels like RetroRGB and DFRetro, who will, no doubt, in the very near future, be putting out very comprehensive videos with scientific measurements down to the specific individual frame, and they’re far better qualified to talk about that stuff than I am, and they’ve got all the kit to measure that.

So I thought I’ll leave that because it’s not something I know a lot about, it’s not something I’m actually qualified to measure.

The third thing being that I was actually testing the scaler mode specifically, and that does have- it has higher lag than the line multiplier mode, there’s no secret there, and Markus is very actively working on improving that, and it doesn’t make sense for me to report on something that’s so heavily in development and that’s going to be improving by quite a lot in quite the near future, if all goes to plan.

Yeah, and obviously bearing in mind all the stuff that I’ve previously said, so that’s that.

But one thing that did come up, and it was one of my patrons who asked me this question, and also a very good friend of mine, my good friend from the Netherlands. Goes by the name of Custardo on the internet, his real name is Erwin Bierhof.

Really lovely guy, met him a couple of times. Got drunk with him a couple of times, as you do!

And he asked about the Atari ST. Now, that video I did actually hook the ST up and test it, and I spent quite a bit of time testing this and recording it, and you know, I wanted to test the 50Hz mode and the 60Hz mode - low res, medium res, and all of that, and I didn’t actually test the high res.

Now, one bit of feedback that I did have on the RetroTINK when this first came out: a friend of mine - Chrissy is his name - was working with Mike Chi who actually designed this thing, to try to get the Atari ST dialed in properly, because they’re notoriously flaky.

Obviously they’re a product of that 1980s Tramiel era Atari - everything’s a little bit wonky and not 100% perfect, and quite a challenge for these scalers to actually be able to handle. And, as far as I know, they did get that sorted, working on that together, so it’d be very interesting to see how the OSSC Pro handles it.

I know from the limited testing that I did the other day that it does handle the low res mode perfectly fine, 50Hz and 60Hz. Looks great, looks fantastic, so that’s good to see. But I thought actually, obviously the high res mode is quite important to people, and I didn’t have this with me on the day, so I couldn’t test that.

This is an Atari ST to VGA adapter. I have the SCART cable here in the studio, but I didn’t have this, and of course the ST won’t output high resolution over SCART, so I need this adapter to be able to test that, which I now have. So I’ve got that, and I thought, you know what? Let’s just do a very quick video, a very informal thing, unscripted.

Sit down together, try out the ST with the various different video modes with these different scaler devices: so I’ve got the OSSC, I’ve got the RetroTINK 5X, and I’ve got the OSSC Pro. This is by no means a scientific test, this is just hooking things up and seeing if it looks any good, as usual.

So there we go.

I’ve updated these scalers this morning so this is running on the 0.9 firmware - there is a hardware mod that you can do and there’s a 1.x beta firmware that you can run on these that apparently improves a few things - I haven’t done that mod to this.

The RetroTINK, that’s running on the latest firmware as of today.

The OSSC Pro, that is a prototype unit, but Markus is backporting all of the features and functionality from the final unit. There’s some very, very minor hardware differences, but it just means that you can’t run the final firmware on this thing. So he’s backporting stuff and this is fully up to date with with the prototype firmware as well.

So as far as I’m concerned all of this is fully up to date.

So yeah, let’s dive in and do some testing with the Atari ST with these various scaling devices - and as I’ve got the original OSSC plugged in and ready to go, I think we’ll start with that one.

So let’s see how it looks!

So this is the ST - this is actually my STE, I forgot to mention that at the beginning, but it doesn’t really make any difference whatsoever, the video output’s exactly the same. But yeah, this is my ST hooked up to the original Open Source Scan Converter, it’s running in low resolution mode just over SCART into the AV1 SCART input, and we can see that this is a 15kHz 50Hz signal, near enough.

I’ve got four times line multiplying on and there we go - I’m also simultaneously capturing this in OBS on my laptop so we can get a nice raw video capture. The monitor’s stretching the image but that’s just- I can’t be bothered with fiddling with things. I want to see how stuff just works straight out of the box without any configuration because it can only get better from here once you start tweaking stuff.

So if I just go in to “Set Preferences”, now changing this to medium resolution, I don’t think this is going to make any difference at all as far as the OSSC is concerned, I think the actual video signal is the same - it’s still a 15kHz 50Hz signal - so no issues there.

And if I just go in and the refresh rate on the ST is actually changeable- it’s software defined, it changes in software.

So a lot of earlier machines were kind of locked to 50Hz or 60Hz depending on what region they came from - obviously NTSC machines being 60Hz and PAL machines being 50Hz, but the ST was kind of one of these, kind of the first generation of these machines that could have that defined in software, which of course is the thing nowadays, it’s how computers have been ever since.

Not making any claims that it was the first or anything like that or that it was particularly special in that regard but what it does mean is that we don’t need separate PAL and NTSC machines to be able to test this and this is one thing that I wanted to show off in my first video just because I love showing this off - and this is the Atari STE port of Wolfenstein 3D and this is running- this STE has been upgraded to 4MB of RAM, they’re just 30 pin SIMMs in these machines so it’s literally just a case of dropping some SIMMs in there and job done. It’s unaccelerated - nothing fancy going on there, just the bog standard 68000 CPU with that 4MB of RAM. And this runs at 60Hz, so just another thing to test really.

And, you know, I love having an excuse to show this off. I did upload a video on this on my channel a while back, but that was quite a while ago and the channel has grown quite a bit since then. So this looks absolutely fantastic on this screen. A really, really sharp looking image. Obviously I’ve got the capture to be able to compare to as well.

Of course it’s not as fluid and as smooth as the original PC version. But yeah, bear in mind this is running on a 68000 CPU, so quite impressive really, and great game for testing out video modes and stuff like that.

But as we can see, that’s working great, no issues at all whatsoever with the original OSSC.

So let’s get that little VGA dongle hooked up and we we will boot into high res mode and see how it handles that.

So this is high res mode, and it’s a really weird video signal, it’s at 35.8kHz and 71.47Hz so that’s very odd - I mean, that’s just what the OSSC has detected it as.

As we can see, we have a picture here, but it’s not ideal, is it!?

I mean, it’s usable, I guess? But it’s off to the side. It’s got this weird banding thing going on where obviously stuff isn’t being scaled very effectively. Now, I don’t have anything, I don’t have Cubase or anything on my UltraSatan hard drive emulator thing here to be able to show you that.

Obviously, the menus and things are all off the top of the screen, so not not really all that usable. Now, of course, you can tweak all of the video timings and everything to your heart’s content with the OSSC. I’m not going to do that today - this isn’t a guide on how to get the ST working with the original OSSC.

I just want to see how it works out of the box - and as we can see with the ST’s high res mode, this is not ideal. So I think what we’ll do is we’ll move on to the OSSC Pro next and see if the situation has improved.

So this is the new OSSC Pro, just running the exact same input that I first started with on the original OSSC - so this is a SCART connector into the ST’s RGB monitor port, completely bog standard setup. This is running in low resolution at the moment. As we can see, it’s detected that 15kHz, 50Hz video signal, and it’s already looking much better - the positioning on the screen is absolutely perfect, the scaling is absolutely perfect, so that’s a very very nice initial win for the Pro.

Now, you can actually operate these with the original OSSC remote, I think, as far as I know but I haven’t paired it - there’s a process you have to go through to train it like one of those universal remote things, and I couldn’t be bothered with that. The buttons on the front are more than sufficient for operating this thing.

So I will just show you what the situation is. So here we have the mode that this is in, the output mode is line multiplier mode, same as we had the original OSSC in. There is also - if I just change this - there’s also a scaler mode which works slightly differently. Basically this just locks the output signal to a nice steady 1080p 60Hz signal and basically whatever you throw at it, it will output that lovely steady signal.

So really, really cool - not just a basic line multiplier and that’s the mode that I’m going to predominantly be using this in. But we’ll go back to the basic line multiplier just to make this a fair test.

There we go!

And if we just pop out of this and go to the line multiplier options, we can see this is in Adaptive mode.

There is another mode that this supports - I’ll just change this to Pure - and yeah, I’m not really sure what kind of difference that makes, I think Adaptive does some intelligent stuff with the output to try and make sense of it, which is obviously why the aspect ratio and stuff is correct. So we’ll just leave all this stuff on the completely default options as we had before to make it a fair test.

So we’ll go back to our resolution thing - obviously change this to medium resolution just to test that out - obviously looks great.

I mean, the picture quality is a big improvement - there is still some banding and stuff and that can probably be tuned out a bit just by tweaking the specific settings on the Pro, but I think that’s a great basis to work with.

You know, great starting point, I should say - and again, let’s go down to Wolf3D and we’ll run that just in the name of completeness.

As you can see, that has switched to 60Hz, I hope you can see that, and yeah, so that thing that pops up, the Sirius Cybernetics Corp, they’re actually a demo group who do demos for the Atari ST, and they’re the ones that actually made this game.

And I’m not showing it off here, I’m not actually capturing audio, but it does actually have music and sound effects as well, which is quite cool.

I do love this, it’s a fantastic thing - a wonderful effort on their part.

So we’ll just load this up just to see how it looks and obviously get some footage captured from this on the old Cam Link through OBS.

That’s just switched resolution, no problems at all.

…and we’ll just have a little play through, but looking absolutely fantastic on the OSSC Pro. I think this is- and you know, it’s not, it’s not a big night and day improvement, but- just on the default settings, just as a starting point to start tweaking from - hopefully you’ll agree that it does does look a little bit better than it did on the old OSSC.

Now this is quite exciting because obviously, as you can see, this is immediately a massive improvement. Obviously a bit weird with the old scaling and stuff - this is completely default settings, like I say, on the line multiplier mode. But yeah, a bit weird on the default scaling and screen position but we have an image which is-

I think it’s looking a lot better than it was on the original OSSC. So if we just change the output to the scaler, let’s see how it handles that.

Yeah, it’s still a bit weird, but it’s slightly bigger. We’ll switch back.

So yeah, that’s very interesting - very interesting indeed.

What am I doing!?

So I will just go back to- let’s try that Pure mode and just see what happens with that…

Actually, that’s kind of pretty much exactly how it was looking on the original OSSC. So that’s just the pure output. So it’s actually the Adaptive mode that’s, that’s kind of fixing that picture.

And again, of course, you can tweak video timings and stuff like that - and It’s part of my job to actually test this thing, so I will also be feeding this back to Markus as well.

But yeah, that’s the high resolution mode, and that’s running over the VGA connector, but that’s looking really clean - I mean that’s very usable, and of course you could tweak the image position and stuff like that from there.

You know, if you’re using Cubase or one of those applications on the ST that requires that high resolution mode, that’s very usable and very nice.

So, of course, I did promise at the beginning that I would be testing out a third scaler which is the RetroTINK 5X, so let’s compare that to the other two and see how that works with the ST.

So we’re now running on the RetroTINK 5X, like I say, this is running the absolute latest firmware available for this as of today, and it’s connected over that SCART cable from the ST’s RGB monitor socket, as before.

And we can instantly see - and this is an issue that I have come across with the ST before with the RetroTINK - and if you look very closely, you can see that there’s actually this flickering that’s happening kind of halfway down the screen, which is to do with the video timings and stuff not being quite right and quite matched up.

Of course, the RetroTINK does have some advanced options for tuning the timings and things, I’m not going to go into it here because obviously this is just a test of how stuff works straight out of the box. I know it probably sounds like a bit of a cop out and, to be honest, it partly is - but also, you know, I’m very lazy. I just like stuff to work. You know, if I plug it in and it works, then that’s great, I’m going to go with that option rather than the one that requires a lot of fiddling. That’s just how I am. And of course there is the, there is the RetroTINK 4K that’s out now as well in quite limited quantities. I know Mike has released a few batches of those, so it’d be interesting to check that out as well if and when I finally get my hands on one.

record scratch

Huh, strange - so actually, scratch what I just said about that weird video interference because I’ve just rebooted the machine - I messed up and launched the wrong thing by accident and had to reboot it and… it’s gone! So yeah, it’s sorted itself out. Not quite sure what was going on there. I know my friend Chrissy worked with Mike Chee to get these video timings and things a bit more dialed in on the ST so hey, that’s good!

That’s gone, and we’ll just go in and we’ll just double check the medium resolution again - no need to do this, but I’m gonna do it anyway to show you what it looks like, so there we go.

Oh, by the way I should probably say that this this STE is running Rainbow TOS - I think it’s 1.62 - one of the later ones with lots of fixes and things built in.

And let’s go down and we’ll just try to launch Wolf3D again, check out that 60Hz mode and see how that lor-


I can’t speak today! Anyway…

So, looking really nice in this 60Hz video mode, and one thing I should point out - this frantic flickering of this “Get Psyched” loading thing, this is nothing to do with the scalers themselves, this is just to do with the unpacking process on the ST, and however it loads this game into memory.

I’ll just double check my capture still running, yes it is.

Right, so… This is running in that 60Hz mode, and I actually think that this is the best of the three out of the OSSC, the OSSC Pro, and the RetroTINK 5X.

I mean, this picture is really, really nice, this is absolutely perfect, and you can tell they’ve put a lot of work into getting this dialed in perfectly.

Of course, we did see the usual banding and stuff on the desktop, but to be honest, I think that’s just an ST thing.

You know, Atari made their own little CRT monitors for these back in the day and that was kind of how they were designed to be used so it was never designed to be upscaled and displayed on a 1080p or a 4K display but yeah, that’s that.

So, of course, that’s the low resolution and the medium resolution mode tested - that weird flickering issue that we initially saw has gone away, I don’t know if that was to do with the machine itself, that is something I have seen previously on the 5X but hey, maybe rebooting it meant that it redetected the video timings and stuff so that’s all good.

But how are we going to test the high resolution mode?

Well, I think I have something that might work, but it also might not - so let’s have a look at that.

So this is where we potentially run into a problem because the adapter that I’ve been using is this one, which goes from the ST’s built in RGB monitor connector to a standard VGA cable. And the other cable for the low and medium resolution mode is this one, which goes to a SCART connector.

Now the RetroTINK 5X has a SCART connector on it, as you’ve as you’ve probably seen - it’s the wrong way round which is a bit of a bone of contention but that is fixed on the new RetroTINK 4K. But it doesn’t have a VGA connector on it, which is a bit of an issue.

And the ST actually detects what kind of monitor it has plugged into it - so back in the day, if you had the high resolution monochrome monitor and plugged that in, then it would output in high resolution mode. If you had the standard RGB color monitor, it would only allow you to output in low and medium resolutions - and these cables do kind of mimic that with the pins that they have connected internally.

And you can’t output the high resolution signal over a SCART connection because why would you? It doesn’t make any sense! It’s a 70Hz signal, it’s not going to work on any kind of TV that has a SCART input.

So I do have a solution but I haven’t actually tested it - I’ve never actually managed to get this thing to work properly!

And this is called a VGA2SCART - it says on it “Produced by Retro Upgrades - - designed by RetroTINK”.

So this is the official RetroTINK VGA to SCART adapter. So it’d be very interesting - and I know I’ve tried this with a much, much older firmware, and it didn’t work at all. It didn’t even recognize that there was a signal there.

But it’ll be interesting to see if we can get the high resolution signal from the ST to actually display on this monitor via the RetroTINK, via this very convoluted setup with the whole SCART thing. So let’s plug this in.

And then this plugs into the…. Where are we?

That’s not plugged in anymore!

Good start.

So the VGA connector plugs into there. It has audio inputs on it as well, and the STE does have stereo phono - you know, RCA - audio output as well so I could connect that if I wanted to. I’m not going to bother because I’m not all that interested in audio at the moment, but obviously that’s quite convenient that that’s there.

And then this is just a standard fully wired SCART cable that just goes from our VGA2SCART into the SCART socket on the RetroTINK and I’ll just hit record on my video capture just in case something does happen… and that’s that.

The RetroTINK’s on, that’s all connected up. So let’s switch this on and see what happens!

A Few Minutes Later…

So as suspected, that looks like something that’s not been fixed on the on the latest firmware. Again, generally, SCART stuff doesn’t use 70Hz signals, so I can tell why that’s not supported. But just wanted to test that setup just in case, so obviously if you’re wanting to use the high resolution mode on the ST, the RetroTINK 5X doesn’t have that VGA input, so unfortunately I don’t think that’s going to be an option.

But hey, worth testing.

Obviously I can see that the ST is working, the power lights on, the light’s been flashing away on the UltraSatan there so that’s just loading up as normal, but it didn’t work.

So, an interesting set of tests I think, and hopefully that’s some useful information to somebody out there.

So, interesting, very, very interesting looking at the outputs from all of these various different scalers with the Atari ST, and I hope that’s been some useful information to someone out there. Of course, Erwin asked that question initially, and maybe that satisfied your curiosity as well - it certainly has raised some questions for me, as well as answering a few.

I would like to go through and tweak some of these settings and try and dial things in a little bit better, but that’s going to take some time, so I just wanted to do a very quick test. I am incredibly lazy, of course, I just like to plug stuff in and have it work.

I’m sure there’s plenty of other people out there who are just like me!

But yeah, interesting, interesting stuff.

So just a very quick recap, obviously:

High resolution mode: not an option on the 5X because it doesn’t support 70Hz over SCART and doesn’t have a VGA input, but low and medium resolution, which is what you’re going to use for all of the games that are out there, basically - you know, it’s only if you’re interested in Cubase and desktop publishing and that sort of desktop software that you’re going to be using that high res mode. Yeah, perfectly, you know, really great option - probably the best option for those lower resolutions.

The OSSC - the original one - doesn’t really like the high resolution mode at all!

You’ve got a bit of the screen there but it’s all scaled weirdly, and a big chunk of it was chopped off - so not ideal!

OSSC Pro looks absolutely fantastic, but it doesn’t quite fill the entire screen.

It’s looking very, very close, and hopefully that’s something that can be sorted in a future firmware update.

But at the very least I could capture that footage, and I could just crop it and resize it in my editor, and it would do.

And of course, speaking of firmware, there is the original OSSC, and there is a beta firmware and a hardware mod that you can actually do to these original OSSC units now, which changes the way that the video processing - well some of the video processing pipeline works - I don’t claim to understand it all in great detail, but it does involve some very fine soldering.

It involves removing a surface mount resistor and also soldering a little patch wire to the - I believe it’s to the video processor chip or maybe the FPGA chip to somewhere else on the board. I don’t want to do that today because I’m running out of time and I would have to rush it and I don’t want to risk breaking this thing because it has been so incredibly useful to me over the years so I’ll probably do a dedicated video on that mod, capture a load of footage before and after, and kind of try and show what difference that makes.

But again, hopefully that was useful to somebody, certainly useful to me. Thank you ever so much for joining me, and if nothing else I hope it was a nice distraction from - well, whatever it is you want to distract yourself from.

So, thanks again, don’t forget to subscribe to the channel if you want some more updates and some more testing on the OSSC Pro and more Atari ST stuff, more computer stuff, more additional slightly more laid back, unscripted, unstructured stuff alongside the main channel, ctrl-alt-rees, so thank you ever so much, and I’ll hopefully see you next time.

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Relevant Links:
OSSC Pro Testing Video:
Wolf3D STE Video:
RetroTink 5X / 4K:

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