exxos's Atari, Amiga & retro forum

I am looking for a cable to get high resolution mode on my STe on either a OSSC or a RetroTink 5X (have both).

As far as I understand the ST, you need a special cable that is vired (reset signal I think) so the ST "knows" that is connected to a monitor that can show 640x400 in black and white. The SM124 for instance have the cable built ind for the factory.

Both the OSSC and the RetroTink 5X can show that resolution so I an looking for a cable with the correct adjustment. Preferably a scart cable since both the OSSC and the RetroTink can handle that.

If such a cable exits :-)

I think scart cables are only wired for colour, as there weren't any high res mono monitors using scart. You might need to modify an existing scart cable with a switch which grounds a certain pin which turns high res on. This post should help: https://forums.atariage.com/topic/30962 ... art-cable/

Do some Atari ST to VGA converters have a switch for mono? Maybe you could do it that way. (Edit: yes I just checked, most do)

Thank you for the link. Will check the many suggestions :-)

I am not that great of a solderer, so I would prefer a finished cable. Can be both a DIN to SCART cable with the correct reset or a DIN to VGA.

The OSSC both has SCART and VGA input. SCART is preferred since it has a filter.


The discription of the port" AV3 In – Standard D-Sub15 (VGA) connector. You can connect sources such as the Sega Dreamcast or a retro gaming PC. This input does NOT have a sync low pass filter as this is normally not required for VGA connections. Signals up to a maximum resolution of 720p are supported on all inputs."

I've never tried ST to OSSC using VGA, but a standard DIN to VGA Mono cable can be had here: ST Mono VGA cable.

CoolNovelties make very good cables, I recommend them a lot.

I don't believe it is possible to have mono over SCART, but this cable works great (I have one) and if you can get one of these VGA Switcher you can use low and medium resolutions with a suitable 15Khz capable VGA display. This may work with the OSSC, but I haven't tested it.

No, you can’t have mono over SCART with a normal ST unless you rewire the SCART cable completely. Mono signal is on a different pin and not connected on SCART cable.
Best solution with OSSC is to use the VGA input and an ST2VGA adapter on ST side.

BTW, above statement does not a apply to a Phoenix H5 ST as the Mono signal can be internally connected to the RGB pin(Like ST2VGA), but that’s limited to H5, not original STs.

Thank you all for the great advise! :D

I think I will try one of those DIN to VGA Mono cables and see how my OSSC reacts to that.

JohnFante wrote: 22 Jun 2025 18:22 Thank you all for the great advise! :D

I think I will try one of those DIN to VGA Mono cables and see how my OSSC reacts to that.

BTW it has to specifically be a Mono cable because it is wired to tell the ST it's mono. That cable should be specifically that.

The VGA adapter from exxos store has a switch to allow changing from Mono to colour modes FYI.

This is a bummer! :-(

I live in Denmark and due to customs CoolNovelties do not ship to the EU any more ...

Does anybody know another place where I can buy the ST Mono VGA cable cable?

https://coolnovelties.co.uk/shop/atari- ... 05459.html

Found another solution: https://sidecartridge.com/products/st2vga-atari-st/

Thank you for all your help!