SIMH

SIMH is a highly portable, multi-system emulator which runs on Windows, Linux, macOS, FreeBSD, OpenBSD, NetBSD and OpenVMS. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, and has been in development in one form or another since the 1960s.
History.
SIMH was based on a much older systems emulator called MIMIC, which was written in the late 1960s at Applied Data Research. SIMH was started in 1993 with the purpose of preserving minicomputer hardware and software which was fading into obscurity.
Emulated hardware.
SIMH emulates hardware from the following companies.