my first pc was a dec Rainbow, came with CPM and DOS...
i was using RSX at work so...
I had a Dec Rainbow 100 on loan from work. I do recall it being dual boot. It warmed my dorm room.
I also later used DR-DOS on an 80386 I built from a jameco kit.
I had a TRS 80 that hardly did anything but it was still pretty fun to tinker with. Then I went to a Commodore-64 which was really fun compared to that. I’m running a 12 core monster gamer with mega ram and a really zippy graphics card these days. One of many game machines I’ve had. How times change huh?
Kaypro forever