Most probably the rarest Atari computer ever, and also a very desirable one !
Very nice machine, I think. But… yikes, no easy way to use external mouse, so instead you get a “vector pad”:
Vector Pad. At this point, track pads had not been invented. The STacy had a built-in trackball, which was common on portable computers. In fact, that’s what the PowerMac 100 used. The ST Book went with something more unique: a vector pad, which is probably more similar to that little “nub” stick you may have seen on some IBM ThinkBooks. You could slightly push the vector pad, a pressure-sensitive disc, in directions to move the mouse around. The more pressure you applied, the faster the mouse moved. This pad was placed in the top right, above the keyboard, which I think would have been incredibly awkward to work with.
I think the ATW (Atari Transputer Workstation) is even more rare. Atari only sold around 80 of them.