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Wikipedia / SIMH

SIMH is a free and open source, multi-platform multi-system emulator. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, based on a much older systems emulator called MIMIC.

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 that was fading into obscurity.

In May 2022, the MIT License of SIMH version 4 on GitHub was unilaterally modified by a contributor to make it no longer free software, by adding a clause that revokes the right to use any subsequent revisions of the software containing their contributions if modifications that "influence the behaviour of the disk access activities" are made. As of 27 May 2022, Supnik no longer endorses version 4 on his official website for SIMH due to these changes, only recognizing the "classic" version 3.x releases. The classic version continues to be maintained, with version 3.12-5 released on 16 July 2024.

On 3 June 2022, the last revision of SIMH not subject to this clause (licensed under BSD licenses and the MIT License) was forked by the group Open SIMH, with a new governance model and steering group that includes Supnik and others. The Open SIMH group cited that a "situation" had arisen in the project that compromised its principles. Open SIMH is governed by a Steering Group that includes Supnik, Clem Cole, Richard Cornwell, Paul Koning, Timothe Litt, and Seth Morabito.

Emulated hardware

SIMH emulates hardware from the following companies.

Advanced Computer Design

  • PDQ-3

AT&T

BESM

Burroughs

Control Data Corporation

Data General

Digital Equipment Corporation

VAX Family Systems

GRI Corporation

Hewlett-Packard

Honeywell

Hobbyist projects

IBM

Intel

  • Intel systems 8010 and 8020

Interdata

Lincoln Labs – MIT MIT_Computer_Science_and_Artificial_Intelligence_LaboratoryResearch Lab

Manchester University

MITS

Norsk Data

Royal-Mcbee

Sage Computer Technology

  • Sage II

Scientific Data Systems

SWTPC

Systems Engineering Laboratories

  • SEL-32 both Concept-32 and PowerNode systems

Xerox Data Systems

References