Sure, machines with virtual memory and caches were available in small numbers for a long time, but the vast majority of programming was done on PCs since the 1980s. The first Intel PC with a cache was the 486.
I learned LISP on systems like an IBM mainframe, DEC-10 with TOPS-10, the DEC VAX 11/780 with VMS, SUN 3 & 4, Symbolics 3600/3640, ... all these had large virtual memories, with the resulting feature that the speed of memory access varies widely between cached memory, main memory and virtual memory.
I doubt that the early small memory Intel-based machines played much of a role for Lisp programmers or even education (other than being used as a terminal to a different machine). Lisp was memory hungry, due to the interactive use (with resident dev tools) with a garbage collected heap. The 386 supported virtual memory and various other ways to extend the available RAM was used on early intel machines under the various DOS variants...
