Several RISC chips for Lisp Machines were under development. Xerox, Symbolics (Sunstone), University of California (SPUR), had projects for that. The AI winter then killed it. The Lisp Machines then were ported as emulators to ALPHA (Symbolics), SPARC (Interlisp) and other processors.
"Also, note that the Sunstone project did address many of the competitive concerns, especially the continual mention of Sun in this analysis. The Sunstone project included a chip design for a platform meant to run Unix and C, as well as Lisp. It was a safe C exploiting the tagged architecture, for example, to allow checking of array bounds. And the Sunstone project was being produced on-time. But to back up the analysis of Symbolics’ priorities, it was cancelled as we were getting the first chips back from LSI Logic."
"Also, note that the Sunstone project did address many of the competitive concerns, especially the continual mention of Sun in this analysis. The Sunstone project included a chip design for a platform meant to run Unix and C, as well as Lisp. It was a safe C exploiting the tagged architecture, for example, to allow checking of array bounds. And the Sunstone project was being produced on-time. But to back up the analysis of Symbolics’ priorities, it was cancelled as we were getting the first chips back from LSI Logic."