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| Open SIMH | |
|---|---|
| Developer | Robert M. Supnik |
| Release | 1993[1] |
| Stable release | |
| Written in | C |
| Operating system | Windows, Linux, macOS, FreeBSD, OpenBSD, NetBSD, OpenVMS |
| Platform | x86, IA-64, PowerPC, SPARC, ARM |
| Type | Hardware virtualization |
| License | BSD-style licenses |
| Website | opensimh |
| Repository | |
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.[1] SIMH was started in 1993 with the purpose of preserving minicomputer hardware and software that was fading into obscurity.[1]
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.[3] 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.[4][5]
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.[6][7]
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
GRI Corporation
Hewlett-Packard
Honeywell
- H316
- H516
Hobbyist projects
IBM
Intel
- Intel systems 8010 and 8020
Interdata
- 16-bit series
- 32-bit series
Lincoln Labs – MIT Research Lab
Manchester University
MITS
- Altair 8800 both Intel 8080 and Zilog Z80 versions
Norsk Data
Royal-Mcbee
- LGP-30
- LGP-21
Sage Computer Technology
- Sage II
Scientific Data Systems
SWTPC
Systems Engineering Laboratories
- SEL-32 both Concept-32 and PowerNode systems
Xerox Data Systems
References
- 1 2 3 "Preserving Computing's Past: Restoration and Simulation" Max Burnet and Bob Supnik, Digital Technical Journal, Volume 8, Number 3, 1996.
- ↑ "Release 3.12-3". 31 January 2023. Retrieved 24 February 2023.
- ↑ "simh repo: Add top level COPYRIGHT and LICENSE files · simh/simh@ce2adce". GitHub. Retrieved 2022-06-04.
- ↑ "SimH "Classic"". simh.trailing-edge.com. Retrieved 3 May 2026.
- ↑ "SimH "Classic"". simh.trailing-edge.com. Retrieved 2022-06-04.
The V4 GitHub repository has been placed under a modified license that effectively makes it closed source. It will no longer be referenced here.
- ↑ "[email protected] | Announcing the Open SIMH project". 2022-06-03. Retrieved 3 May 2026.
- ↑ "[email protected] | Announcing the Open SIMH project". 2022-06-03. Retrieved 2022-06-04.
- ↑ "Altair Other Operating Systems". schorn.ch. Retrieved 2026-04-30.
External links
- Computer Simulation and History Official site
- Additional VAX/MicroVAX models for SIMH
- Running VAX/VMS Under Linux Using SIMH
- Debian Package
- FreeBSD Port
- UNIX: Old School. Using SIMH to explore UNIX history - Matthew Hoskins
- SCSI tape drive emulation for the Raspberry Pi with support for SIMH tape image files
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