A bit of CP/M. I'd say around 82-84? Way too much classic Mac. (Wrote a SCSI driver for System 6, still have nightmares ;). No BeOS, Amiga distracted me from that :)
And plenty of others, just never as the main system.
And plenty of others, just never as the main system.
And yes, needs/utility vary.
Any CPM, Classic Mac, or BeOS experience by chance? (Or others.)