High Quality Content by WIKIPEDIA articles! SIMH is a highly portable, multi-system emulator which runs on Windows, Linux, Mac OS X, FreeBSD, OpenBSD, NetBSD, OpenVMS, and other operating systems. It is maintained by Bob Supnik, a former DEC engineer & DEC vice president and has been in development in one form or another since the 1960s.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.