Sorry, I don't have any suggestions regarding the rolling picture issue, but that is a beautiful monitor!

To answer what I can simply: Since this monitor has TTL and Analog settings and I believe you said it shows a picture (if incorrectly) with VGA, that would make it a true multisync since those are vastly different types of video signals and require different horizontal scan rates.

I recently got my first Atari 1040STf so I have been dabbling in the Atari computer world and learning about their video standards.

The Atari ST line primarily used low\med resolution color modes (15.75kHz horizontal; which does not work on normal VGA displays) and a high resolution 640x400 monochrome mode (31.5kHz, which is compatible with normal VGA displays). These are both analog modes. Later Atari systems like the TT and the Falcon were also able to use VGA displays (I'm not sure if all of them were or the specifics of this), so that might explain yet another reason why this would be VGA compatible... it came out the same year as those computers.

As to why it has TTL support... Atari also put out a series of IBM PC compatibles (creatively named PC-1, PC-2, etc.) which would have started out with CGA and EGA displays, which are TTL.

I guess some models (TT030?) also supported a rather obscure ECL video mode which is a high resolution 1280x960 monochrome mode... though I doubt this monitor is meant for that.

So, what you have there is Atari's solution to make a monitor that works with basically all of their computers aside from the ones that only had RF or composite output. Most likely the rolling screen can be fixed and it will work with just about anything you can plug into it.

... oh, and as if it wasn't obvious, this seems to be an incredibly rare monitor. An actual working multisync that can handle TTL and analog signals is a unicorn of a find these days. I have three in various states of disrepair and have yet to find one working. The fact that you have one that is also Atari branded and is, presumably, pre-wired to work on those systems is awesome.

Just be careful having it set to the wrong thing when you connect a system... I have no idea what that would do. You will probably need adapters to use TTL (CGA\EGA) or other non-VGA modes if it supports them, but it sounds like you have this covered already. I am out of my wheelhouse though at this point so going to AtariAge forums may yield more helpful information about how to adapt this and hopefully how to fix it.

TTL/ANALOG are both 15khz modes

One being CGA the other 256000 color RGBs analog which is Amiga or broadcast tv based.

It is unlikely it is a full multisync though you should be able to adjust the sync dials for minor variations like 640x400-72hz

Given it’s for an Atari tt30 it likely is setup for the modes that machine generated.

Found something interesting here:
https://www-atari--computermuseum-de.translat … r_pto=sc#sc1435

Go to the Atari PTC1426 / TTC1434 section...

It seems the people running that site think that both the PTC1426 and TTC1434 are the same, but they do not have a TTC1434 themselves and yours is totally different than the PTC1426 pictured. The PTC1426 is a 640x480 31.5Khz monitor though, and the TTC1435 model before it is a 640x200 15.65kHz monitor. Perhaps the TTC1434 is the bridge model intended for both functions.

Considering the TT030 supposedly came with this monitor (same site says that here) and that computer has a (large) DA-15-pin video output that is compatible with both VGA mode (640x480) and the older ST modes, I am inclined to think this monitor has to be a multisync. Either the monitor or the computers would have come with the required adapters.

Also, it is worth reiterating that, as far as I know, the only Atari systems that used TTL signals are the IBM PC compatible models that use CGA and EGA so this monitor was definitely intended for use with different types of computers.

The TTL/Analog switch reminds me of the one in my Eizo 8060S. In that monitor, all the input pins are routed through that swich. In the TTL position, it has a CGA/EGA type input (I built an MDA adapter that routes the MDA video pin to green), and in the Analog position, it has a pinout compatible to PGC/NEC multisync (1=R, 2=G, 3=B, 4=HSYNC/CSYNC, 5=VSYNC, 6=Rgnd, 7=Ggnd, 8=Bgnd, 9=digital ground). Analog VGA monitors have a DC impedance of 75 ohms on the R/G/B inputs, and multiple ground pins. It should be easy to tell ground pins (75 ohms to ground), sync pins (typically some kOhms to ground) and ground pins apart just by resistance measurement.

I don’t think this monitor is identical to the PTC1426. That monitor has a fixed 15-pin VGA style cable which corresponds to the output connector on the Atari TT030. It has a switch on the back to select between TT frequencies and PC VGA (both analog but slightly different).

This one looks like it is primarily designed for CGA/EGA TTL, hence the 9 pin cable. But the fact that it has a switch for Analog mode means you should be able to bypass the RGB circuitry and get it to do VGA. It’s just a matter of finding the right pins. VGA really only needs 6.

Beerfloat wrote on 2026-02-07, 23:11:

I don’t think this monitor is identical to the PTC1426. That monitor has a fixed 15-pin VGA style cable which corresponds to the output connector on the Atari TT030. It has a switch on the back to select between TT frequencies and PC VGA (both analog but slightly different).

This one looks like it is primarily designed for CGA/EGA TTL, hence the 9 pin cable. But the fact that it has a switch for Analog mode means you should be able to bypass the RGB circuitry and get it to do VGA. It’s just a matter of finding the right pins. VGA really only needs 6.

I definitely think that site I linked to was incorrect in saying that the PTC1426 and the TTC1434 are the same, and the OPs monitor seems like proof of that. Most likely this monitor is just so rare and the documentation so scarce that someone assumed that "TTC1434" was referring to a more common model.

Regarding the connector, a lot of early VGA cards and monitors used a DE-9 as well, so the connector alone doesn't necessarily mean that it was not meant for VGA, though if there is a way to figure out the pinout that would explain a lot. The existence of an analog\TTL switch seems to imply that it was meant to be used on PC-compatble CGA\EGA systems (like Atari's PC line) in addition to analog displays. I suppose it is possible Atari put out a display that could only do EGA\CGA TTL for their PC line and the low\medium resolution analog modes (15.75kHz) supported by the older Atari ST line, but they used this monitor in the early marketing materials for the TT030 (which can output to a VGA monitor) while advertising that the system can do 640x480x16:
https://www.atari-computermuseum.de/pics/scan … /TT030_0890.pdf
https://www.atari-computermuseum.de/pics/scan … /TT030_0392.pdf

Honestly, there is so little out there about this monitor that cricket (OP) should probably contact the Atari Museum. I don't think they even know this thing exists outside of marketing materials and I don't think they know that it is TTL\Analog switchable.

One thing I don't really understand is why the monochrome (640x400) Atari ST monitors listed on the site are labeled as "TTL". Unless I am misunderstanding something, the ST does not output a purely digital TTL signal for any of its display modes, and they are all analog. Maybe just part of it uses TTL? I see some mention online of TTL sync signals. Anyway, I have hooked up a very simple adapter from my 1040STf to a modern VGA monitor and the monochrome high res mode works without any problems... if anything is done using TTL it must not be vital because an analog VGA monitor would not be working otherwise. The site also calls the SC1435 a "CGA" monitor, while also saying it is compatible with basically all ST models... I don't know what's going on there to be honest.

Anyway... yeah. Very rare monitor. I would be very careful testing things on it until you understand exactly what you're dealing with. I would suggest posting at an Atari specific forum to hopefully dig up some more concrete information on this. Feel free to give a link to this thread so they can see some of this additional info that has been dug up (it is mostly conjecture, but it may be helpful).

https://www.atari-forum.com/viewforum.php?f=57
https://forums.atariage.com/forum/20-atari-st … lcon-computers/

My suspicion is it only does multisync up to a tad below VGA frequency... at least it would do, if it was the US model. I think maybe they bodged it for sale with the German Atari ST only to German TV standard, and swapped an NTSC reference crystal out for a PAL one.... resulting in nothing else working, since CGA is derived off same crystal, possibly EGA can be too, at least low res.

I would try the following, analog mode, VGA physical pin converter, supported VGA card by the PAL version of one of these drivers (BIOS will still be scrambled, but pic should come in when you run it from the prompt) https://www.epanorama.net/circuits/vga2tv/driver_dos.html I have had VGATV working on PAL TVs with Cirrus Logic and Trident chipsets.

Ozzuneoj wrote on 2026-02-08, 02:57:

Regarding the connector, a lot of early VGA cards and monitors used a DE-9 as well, so the connector alone doesn't necessarily mean that it was not meant for VGA

Yes but I think most (all?) of those cards would typically only output their CGA/EGA compatibility modes over the 9-pin connector, not their VGA modes.

though if there is a way to figure out the pinout that would explain a lot. The existence of an analog\TTL switch seems to imply that it was meant to be used on PC-compatble CGA\EGA systems (like Atari's PC line) in addition to analog displays.

Yeah I reckon that was the idea, primarily for Atari PC1, PC2 or PC3, with a dongle for the TT.

Beerfloat wrote on 2026-02-08, 05:33:

Ozzuneoj wrote on 2026-02-08, 02:57:

Regarding the connector, a lot of early VGA cards and monitors used a DE-9 as well, so the connector alone doesn't necessarily mean that it was not meant for VGA

Yes but I think most (all?) of those cards would typically only output their CGA/EGA compatibility modes over the 9-pin connector, not their VGA modes.

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) cards that also have them.

I just grabbed one of the first things that came up in a google search, but there is a lot of info from a lot of knowledgeable people here on this subject:
https://forum.vcfed.org/index.php?threads/9-p … -pin-vga.50491/

I have some cards and some monitors that either have dedicated 9-pin VGA ports or in the case of some multisync monitors there are 9pin ports that double as either VGA or TTL depending on the switch (like the one in this thread, except without an attached cable).

Ozzuneoj wrote on 2026-02-08, 05:53:

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) card […]
Show full quote

Beerfloat wrote on 2026-02-08, 05:33:

Ozzuneoj wrote on 2026-02-08, 02:57:

Regarding the connector, a lot of early VGA cards and monitors used a DE-9 as well, so the connector alone doesn't necessarily mean that it was not meant for VGA

Yes but I think most (all?) of those cards would typically only output their CGA/EGA compatibility modes over the 9-pin connector, not their VGA modes.

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) cards that also have them.

I just grabbed one of the first things that came up in a google search, but there is a lot of info from a lot of knowledgeable people here on this subject:
https://forum.vcfed.org/index.php?threads/9-p … -pin-vga.50491/

I have some cards and some monitors that either have dedicated 9-pin VGA ports or in the case of some multisync monitors there are 9pin ports that double as either VGA or TTL depending on the switch (like the one in this thread, except without an attached cable).

Ok. I was aware that there are monitors out there that have 9-pin VGA inputs that rely on not-quite-standardized cables to connect to standard VGA 15-pin outputs (and hopefully this Atari is one of those).
But I've not come across any video cards with actual 9-pin VGA outputs. I'll take your word for it that these are a thing!

Beerfloat wrote on 2026-02-08, 06:39:

Ozzuneoj wrote on 2026-02-08, 05:53:

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) card […]
Show full quote

Beerfloat wrote on 2026-02-08, 05:33:

Yes but I think most (all?) of those cards would typically only output their CGA/EGA compatibility modes over the 9-pin connector, not their VGA modes.

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) cards that also have them.

I just grabbed one of the first things that came up in a google search, but there is a lot of info from a lot of knowledgeable people here on this subject:
https://forum.vcfed.org/index.php?threads/9-p … -pin-vga.50491/

I have some cards and some monitors that either have dedicated 9-pin VGA ports or in the case of some multisync monitors there are 9pin ports that double as either VGA or TTL depending on the switch (like the one in this thread, except without an attached cable).

Ok. I was aware that there are monitors out there that have 9-pin VGA inputs that rely on not-quite-standardized cables to connect to standard VGA 15-pin outputs (and hopefully this Atari is one of those).
But I've not come across any video cards with actual 9-pin VGA outputs. I'll take your word for it that these are a thing!

Hybrid MDA/CGA/EGA video cards many times sort of supported 16 color vga over the pga 9pin out.

9 pin VGA is actually PGA .

The 9 pin PGA pinout lived on for reasons unknown into the early 90’s as vga compatible 9 pin screens.

I too have never seen a 9 pin vga card, only 9pin vga/pga monitors and 9pin hybrid video cards that sometimes supported analog output but still limited to 16 colors.

Beerfloat wrote on 2026-02-08, 06:39:

Ozzuneoj wrote on 2026-02-08, 05:53:

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) card […]
Show full quote

Beerfloat wrote on 2026-02-08, 05:33:

Yes but I think most (all?) of those cards would typically only output their CGA/EGA compatibility modes over the 9-pin connector, not their VGA modes.

No, there are actual 9-pin VGA connectors. If you google it you'll find VGA monitors with 9-pin connectors, and some (rare) cards that also have them.

I just grabbed one of the first things that came up in a google search, but there is a lot of info from a lot of knowledgeable people here on this subject:
https://forum.vcfed.org/index.php?threads/9-p … -pin-vga.50491/

I have some cards and some monitors that either have dedicated 9-pin VGA ports or in the case of some multisync monitors there are 9pin ports that double as either VGA or TTL depending on the switch (like the one in this thread, except without an attached cable).

Ok. I was aware that there are monitors out there that have 9-pin VGA inputs that rely on not-quite-standardized cables to connect to standard VGA 15-pin outputs (and hopefully this Atari is one of those).
But I've not come across any video cards with actual 9-pin VGA outputs. I'll take your word for it that these are a thing!

Yeah, it is definitely far far more common to see them on monitors.

To be honest, I have a foggy memory of a VGA + CGA\EGA card on which both ports with 9-pin, but I am starting to doubt whether that is real or not because it has been a very long time since I've seen that card and I can't find anything like that online.

Still, I do have an interesting old Microchannel video card that I believe fits the bill. Admittedly information about it is slim (and I haven't tested it because I don't know the pinout), but it is called the Control Systems Artist 10/16 VGA, and it has a single 9-pin port on it.

If you search this 1987 article for 10/16 you'll see a snippet about it supporting 1024x768 non-interlaced "while at the same time maintaining compatibility with IBM's video-graphics-array standard." ... which is funny to read like that, because the standard was so new that simply saying "VGA" again wouldn't have meant much to a lot of readers. Of course, at this time sticking a DE-9 on a video card and labeling the card "VGA" is a far cry from having a totally standardized DE-15 that outputs 640x480 at 31.5Khz horizontal refresh.

Still, it has 9 pins, and the card is called "VGA"... if building the correct cable and connecting it to a 31.5kHz monitor presented a usable image, then I guess that makes it a VGA card.

I also have a couple of Moniterm Viking cards (one MCA one ISA) that are somewhat similar to this card (though the HD63484 graphics chip is much larger on those), and each of those has both a 9-pin male and a 9-pin female port. I don't know if any of those are VGA compatible or if they are exclusively ECL... which I know very little about other than that it needs some conversion to work on a VGA monitor.

(And yes, for the eagle-eyed ones, that is the Artist Graphics logo. Apparently Control Systems was either the previous name for or was the parent company of what later became Artist Graphics. They went on to make the GPX accelerator and later the 3GA which they claimed would be a 3D accelerator but so far there has been no sign of 3D acceleration in the drivers.)

Ozzuneoj wrote on 2026-02-08, 07:46:

Of course, at this time sticking a DE-9 on a video card and labeling the card "VGA" is a far cry from having a totally standardized DE-15 that outputs 640x480 at 31.5Khz horizontal refresh.

Still, it has 9 pins, and the card is called "VGA"... if building the correct cable and connecting it to a 31.5kHz monitor presented a usable image, then I guess that makes it a VGA card.

The 10/16 card has a Bt478 chip located directly next to the monitor connection. This is an VGA-compatible RGB digital-to-analog converter. This makes it likely that the card is indeed able to interface VGA monitors.

Ozzuneoj wrote on 2026-02-08, 07:46:

I also have a couple of Moniterm Viking cards (one MCA one ISA) that are somewhat similar to this card (though the HD63484 graphics chip is much larger on those), and each of those has both a 9-pin male and a 9-pin female port. I don't know if any of those are VGA compatible or if they are exclusively ECL... which I know very little about other than that it needs some conversion to work on a VGA monitor.

While this card does not. The chips next to the monitor output are Motorla MECL M10H series chips, so this is clearly some ECL-type interface instead of analog VGA. If that card is exclusively black/white, there is no point in adding an analog output over using a digital one. ECL makes a lot of sense at high resolutions.

Ozzuneoj wrote on 2026-02-08, 07:46:

To be honest, I have a foggy memory of a VGA + CGA\EGA card on which both ports with 9-pin, but I am starting to doubt whether that is real or not because it has been a very long time since I've seen that card and I can't find anything like that online.

I had something like that kicking round in the 90s, 8 bit edge connector, think it had a PEGA chip, so either that was stretched for VGA or it had separate for EGA. Though I think there was also one of the ATI VGA wonders that instead of the round socket for bus mouse had a male 9 pin.