In this case, MSPU had the exclusive on the story:
As noted by the patent name, the feature would let users make notes on the screen of a device, such as a phone, tablet, or PC, while the device is in low-power suspend mode.
The patent was applied for in March 2018 and appears to have been granted yesterday, 3rd March 2020.
While there appears to be prior art, Microsoft’s implementation appears to be more sophisticated than Samsung’s.
For one, the device would actually be in sleep mode, with a display controller in communication with a digitizer via a bypass rendering path that bypasses the processor. Pen strokes would be passed to a memory buffer in what Microsoft calls “darkboard rendering”.
Microsoft notes that unlike other implementations, it would not need to be triggered by the removal of a stylus for example, but would always be available. Because it bypasses the operating system it would also be immediately available, with a latency of around 30 milliseconds, versus several seconds for other screen off writing implementations.
The full patent can be seen here. All very interesting - the Surface Neo has an optional stylus that attaches magnetically, while the Surface Duo (Surface Phone) supports all Surface Pen interations, is it possible that these can be matched to darkboard rendering in the new devices to fully realise this patent? I have my doubts - but there's a good chance we'll all be scribbling on Microsoft folding form factors with the displays turned off in 2021...