Not sure what he means by "train", but Simula 67 included a module for performing "simulations", which was the original point of the language (Simula 1 was a simulation-specific language; Simula 67 was a general-purpose language with simulation in the standard library.)

The simulation module was a framework for defining parallel processes that worked with discrete, scheduled events, a bit like actors. This was intended to model real-world problems such as traffic systems or factories, that complex interactions and dependencies. A simulation had a time axis, so it ran the processes in simulated time, instead of real time. This may be what Hoare was referring to.

Further reading:

http://simula67.at.ifi.uio.no/Archive/Intro-simula/intro.pdf

http://heim.ifi.uio.no/~steinkr/papers/HiNC1-webversion-simu...

Wow that is really neat. Thank you!

Simulated time is not the basis of real concurrency.

Simula-67 (Dahl and Nyaaard) used co-routines in which there was no parallel execution.