Actually just blogging so I can find it again later. Medley Lisp is the successor to the Lisp that runs on Xerox Lisp machines. Two releases run on my Lisp machines: Koto Lisp and Lyric Lisp. Koto Lisp is a pure Interlisp-D environment (by the way, Rainer Joswig put the introductory manual online, and there's also a film about using Interlisp-D online), whereas Lyric Lisp additionally includes an implementation of Common Lisp. Medley Lisp is the direct successor release to Lyric Lisp, thus strongly Common Lisp centric, though the system basis still builds on Interlisp-D. Medley Lisp no longer runs on Lisp machines, but is instead brought to various platforms via an emulator. I still have a version of the emulator for DOS; only an old Solaris version and a Linux version (for Intel processors) are still sold. The software has a long history; the first releases date from the early 1980s, much code from that time is still found in the system (all of Interlisp-D, that is). But I'd guess that the TCP/IP implementation in Interlisp under the emulator version is no longer used; instead, it probably accesses the system's own TCP/IP stack.
At home I still have two functional Siemens replicas of the Xerox 1186 machines, and over a meter of documentation. It's fascinating what's packed into these machines and what performance they already had back then—and this despite the processor not being the fastest. The processor itself had loadable microcode, so the instruction set could be adapted to the system (Smalltalk, Lisp, or Prolog). In principle, that was also an emulator back then, just realized in hardware.