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Applications / Re: OS/2 Architecture Illustration
« on: March 12, 2025, 09:59:15 pm »Hi Greg, thanks for this.Your welcome. I also have this other book in pdf format and here is page 2 on ring 2 and IO.
Reading, OS/2 1.x graphics engine used ring 2 to directly write to the graphics buffer. Presumably OS/2 2.x may have kept the same behaviour but the pages posted don't clarify whether that assumption is true.
I still think DOS also used ring 2, at least on OS/2 2.x to support DOS device drivers.