I disagree with Franko on one point. The start of the personal computer was not a pre-made device you un-boxed and plugged in.
It was machines like SWTPC and Altair.
You built it. Often it took years to get a decent OS.
I wish I still had a 6809 SWTPC running OS9 (they're worth a fair amount of change).
One of the first personal computers. Eventually supporting both multitasking and multi-user.