Here’s an idea of what Tim is talking about (probably not quite the same machine, though), for those who’ve never heard of SGI:—
Remember, this dates from a time when Windows (and Mac OS? not sure) couldn’t even move a window across the screen “live” with its full contents — when you dragged a window by its title bar, it would stay in its original place and you would just drag a rectangle; let go of the mouse button and the window popped over to where you dropped that rectangle (which is why
this is impressive: NeXTSTEP had “live” window-dragging in 1992 when Windows XP could but didn’t even have it enabled by default
ten years later … Of course, you paid rather more for NeXT hardware than for the PC you had at home 30 years ago — though nowhere near what Silicon Graphics charged.)