Portable electronics have come a long way. People kvetch about glued phone components but hey, better than exposed parts shorting out against the case!
A couple of years later someone showed me a PowerBook and that was that.
Unfortunately not very many were made of that one. Only 1000-1200 ST Books compared to the 35000 STacys. It was produced during the downfall of Atari. So they are pretty much unobtainium these days.
The STacy has a battery compartment but in the end Atari decided not to offer a battery option because the runtime was so miserable. They improved that massively with the ST Book (but by cutting the backlight, external video interface and floppy drive among others).