Linus wanted to experiment with the task switching opcodes in the 386 processor. What became Linux started out as two tasks - one printing A and one printing B

Linus wanted to experiment with the task switching opcodes in the 386 processor. What became Linux started out as two tasks - one printing A and one printing B. If you got alternating runs then task switching (and the timer interrupt) worked. From there it is a simple matter to add memory, protection, devices, filesystems, networking, graphics etc :-)