Alto descendants from PARC, ranging in size (not year built) from the Dandelion (AKA Xerox Star) Dolphin and Dorado (an ECL logic screamer). You could boot them into standalone environments like Smalltalk, Interlisp-D, and Cedar/Mesa). By “standalone” I mean you loaded specific microcode into the machine and then booted an environment in which everything: OS, GUI, file system etc was written in that environment.

When I worked at PARC I mostly used Interlisp, but I did use all those environments.