SIMH
 | This article needs more citations. (May 2019) |
| Open SIMH | |
|---|---|
 Open SIMH help screen | |
| Original author | Robert M. Supnik |
| Developer | The Open SIMH Project[1] |
| Release | 1994[2] |
| Written in | C |
| Operating system | Windows, Linux, macOS, FreeBSD, OpenBSD, NetBSD, OpenVMS |
| Platform | x86, IA-64, PowerPC, SPARC, ARM |
| Type | Hardware virtualization |
| License | MIT License[1] |
| Website | opensimh |
| Repository | github |
SIMH is a free and open source, multi-platform multi-system emulator. It was developed by Bob Supnik, a former DEC engineer and DEC vice president.
History
[edit]SIMH was based on a much older systems emulator called MIMIC, which was written in the late 1960s at Applied Data Research.[3] It was a minicomputer simulator created by Mike McCarthy, Len Feshkens, and Bob Supnik that ran on a PDP-10.[4]
The SIMH project began in 1993 and the first version was released by Supnik in 1994. It then transformed from a one-person project to a collaborative effort coordinated on GitHub.[2]
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 behavior of the disk access activities" are made.[5] As of 27 May 2022, Supnik no longer endorses this version 4 on his official website for SIMH due to these changes, only recognizing the "classic" version 3.x releases.
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]
The forked V4 stream is currently being developed at the Open SIMH GitHub. The "classic" version continues to be maintained, with version 3.12-5 released on 16 July 2024, and is available as a tagged branch of Open SIMH.[7]
Emulated hardware
[edit]
SIMH emulates hardware from the following companies.
Advanced Computer Design
[edit]- PDQ-3
AT&T
[edit]BESM
[edit]Burroughs
[edit]Control Data Corporation
[edit]Data General
[edit]Digital Equipment Corporation
[edit]GRI Corporation
[edit]Hewlett-Packard
[edit]Honeywell
[edit]- H316
- H516
IBM
[edit]Intel
[edit]- Intel systems 8010 and 8020
Interdata
[edit]- 16-bit series
- 32-bit series
Lincoln Labs – MIT Research Lab
[edit]Manchester University
[edit]MITS
[edit]- Altair 8800 both Intel 8080 and Zilog Z80 versions
Norsk Data
[edit]Royal-Mcbee
[edit]- LGP-30
- LGP-21
Sage Computer Technology
[edit]- Sage II
Scientific Data Systems
[edit]SWTPC
[edit]Systems Engineering Laboratories
[edit]- SEL-32 both Concept-32 and PowerNode systems
Xerox Data Systems
[edit]References
[edit]- 1 2 "About the Open SIMH project". Open SIMH. Retrieved 23 October 2026.
- 1 2 Supnik, Bob (2015). Walden, David (ed.). "The Story of SimH". IEEE Annals of the History of Computing. 37 (3). IEEE Computer Society: 78–80. doi:10.1109/MAHC.2015.67.
- ↑ Burnet, Maxwell M.; Supnik, Robert M. (1996). "Preserving Computing's Past: Restoration and Simulation" (PDF). Digital Technical Jounral. 8 (3). Digital Equipment Corporation: 23–38. ISSN 0898-901X. Retrieved 21 October 2026.
- ↑ "SIMH FAQ" (PDF). Computer Simulation and History. 6 May 2019. Retrieved 23 October 2026.
- ↑ "simh repo: Add top level COPYRIGHT and LICENSE files · simh/simh@ce2adce". GitHub. Retrieved 4 June 2022.
- ↑ "simh@groups.io | Announcing the Open SIMH project". 3 June 2022. Retrieved 3 May 2026.
- ↑ "Computer Simulation and History". Computer Simulation and History. Retrieved 21 October 2026.
- ↑ "Altair Other Operating Systems". schorn.ch. Retrieved 30 April 2026.
Further reading
[edit]- Supnik, Bob (2004). "Simulators: Virtual Machines of the Past (and Future)". Queue. 2 (5). Association for Computing Machinery: 52–58. doi:10.1145/1016998. Retrieved 22 October 2026.
External links
[edit]- 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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