SIMUL emulates a PDP-11 without MMU and it runs CPU tests loaded from a paper tape. SIMUL used to have a very cool built-in debugger which appears lost.
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SIMUL is written in PL/M language. The idea of PL/M comes from Hungarian system IDOS for Mitra-15. It was reengineered anew by Vladimir Butenko, to become a part of his PhD thesis later (in 1990 or so.)
First version of SIMUL was written by Ivan Bobrov, but it was not finished. I made it work more or less. Late Mikhail Flerov contributed suggestions that made SIMUL no less than 3 times faster.