Yep, I was surprised by the linear stack when I implemented the NoteTaker JS VM with Dan. In the Lively interface, you can stop the running VM and enable the two little checkboxes on the top right to see the whole stack, rather than just the current frame.

Re "the NoteTaker image and VM was also ported to the Dorado": both the NoteTaker image (a.k.a. Smalltalk-78) and the Dorado image were initially generated from Smalltalk-76 running on the Alto. In the Notetaker image there still are branches depending on what system it's running on (see e.g. UserView>>buttons).

Smalltalk-80 was also built on Smalltalk-76 by "backporting" some of the more interesting changes from the Notetaker version, plus adding much more.