> I don't think Linux is any older, and certainly not "much". Be Inc.
It is considerably older on 'normal' hardware. The early BeOS was multi-core in an age when multi-core PCs, and even multi-core workstations, were quite rare.
There architecture on the x86 hardware of the time would have been epic-fail. Even the ringed security architecture of NT 3.5 a few years later was brutal on the hardware at the time [hence the faster but in some ways inferior NT 4.0 that followed].
>and BeOS claims to date back to 1991.
I remember it. And it ran on very proprietary and very expensive hardware. It got some press in the excellent UNIX Workstation magazine and some others [back when there were interesting IT periodicals... sigh].