A little late; amiga-news.de broke the news on the 11th, but the linked Register article covers his work well (and broke the news to me).

His most widely experienced work was a key component of the original Commodore Amiga's operating system. His port of Cambridge University's TRIPOS OS to the Motorola 68000 CPU became AmigaDOS. His rapid work getting it running on prototype Amiga hardware helped Commodore launch the machine in 1985 after its in-house OS project failed to deliver. As he put it himself: "As a result I have the distinction of having written software used by over 2 million users."

The article includes this interview with him from five years ago: https://www.youtube.com/watch?v=pm-szurM5VY

It also points at the comments on Hacker News and Reddit.