Another early example is Stoy and Strachey's virtual machine for running their OS-6 operating system on the Module One minicomputer, starting around 1969 [1,2]. It was written in BCPL. Butler Lampson wrote that it influenced the early pre-Smalltalk OS for the Xerox Alto, also in BCPL [3].

1. https://academic.oup.com/comjnl/article-abstract/15/2/117/35...

2. https://academic.oup.com/comjnl/article-abstract/15/3/195/48...

3. https://www.microsoft.com/en-us/research/publication/an-open...