My father-in-law retired at 75. He was writing firmware for Perkin Elmer chip steppers. I've seen his code, it was pretty nice stuff.
One guy I met was 65 and about to start up another company. He was sharp and definitely knew what he was doing.
The group I was in at Microsoft (Xbox) had David Cutler in it; I think he had just turned 70. I didn't work with him closely, but he was definitely prolific (also more than a bit controversial, politically, at MS, but he had mellowed out quite a bit when I met him).
I had read the book "Inside Windows NT" some years ago (when NT was current). It was interesting. It said that Dave Cutler was the main designer/creator of NT and had worked on VMS (IIRC) before that, at DEC.
One guy I met was 65 and about to start up another company. He was sharp and definitely knew what he was doing.
The group I was in at Microsoft (Xbox) had David Cutler in it; I think he had just turned 70. I didn't work with him closely, but he was definitely prolific (also more than a bit controversial, politically, at MS, but he had mellowed out quite a bit when I met him).
I'm 53 and have high hopes. :-)