MROS API documentation

I know MROS has nothing to do with ASIO, but there is no better fitting subforum.

MROS is an OS extension written by Karl Steinberg himself in the late 80’s for the Cubase releases on Atari ST. It is responsible for timing and routing MIDI events between applications and to hardware interfaces. It is the de-facto standard for using more than the one MIDI interface that is built into the Atari ST.

Since you list only VST and ASIO as APIs that can be licensed and there is obviously no commercial value left in the Atari ST, I would like to ask if you could release the API documentation for MROS. This would allow enthusiasts to breathe new life into their old hardware.

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Wollen wir mal nicht so hart sein.

i have tried to find any documentation here in our archives about MROS (1995), and did not yet find something defining the API in a easy way (only assembler/Pascal code :slight_smile:)
We will check again and keep you inform…


I’m fluent in both languages and I take what I can get.

Any update on this one? What about the code that you already found?

So, one year has passed. Is there still any chance left to get information about the API?

And another year…

I’d like to point out that I did not participate in the reverse engineering of MROS drivers that happened in 2018 over at

@ygrabit, if your superiors told you to not provide any information about MROS please tell me so I can stop hoping.

And yet another year. Let’s hope this “new” forum is better than the old one on