I was careful not to say that Smalltalk invented the process virtual machine. Smalltalk was the first surviving language to popularize the process virtual machine. UCSD Pascal (which was first released in 1978) was actually a branch of Pascal-P2. The Pascal-P system was contemporaneous with Smalltalk (circa 1972). Depending on one’s interpretation, one could argue that Smalltalk also introduced the idea of the process virtual machine.
Similarly, earlier work had been done with O-code for BCPL (circa 1966). But who remembers this?