[Taniwha]

Apple also shipped A/UX which did all that

[wmf]

And was so expensive no one cared.

[rbanffy]

And this is probably the greatest inhibitor Unix had for its adoption.

[switchbak]

They also shipped the Lisa prior to that, which also had protected memory and pre-emptive multitasking. This died for other reasons however (too expensive, upstaged by the mac, etc).