Just to make it clear: Despite reports to the contrary, it is possible to create NewtonOS patches. It’s not for the faint of heart, and you need a german and a US ROM board to erase broken patches, but statements like “Apple is the only one who has the tools to build a new System Update,” and “Building and testing a System Update is complex and expensive process and no single engineer could do it” are plain wrong. The proof is on SourceForge for a simple test patch I created as the start for fixing the [2010 problem](/Pages/Newton Year 2010 Problem), and on UNNA for a more elaborate patch Paul Guyot has put together.
The real challenge is not so much creating a patch, but knowing what to patch and how.