About the Open SIMH project

SIMH is a framework and family of computer simulators, initiated by Bob Supnik and continued with contributions (large and small) from many others, with the primary goal of enabling the preservation of knowledge contained in, and providing the ability to execute/experience, old/historic software via simulation of the hardware on which it ran.

In this way, we hope that modern users can experience a taste of the past and learn from those times to better understand today’s systems. Many features and operations we take for granted came from these systems and made sense as they mapped to the economics of the software and hardware that was available then.

We believe that this goal has been successfully achieved and has for these years created a diverse community of users and developers.

Our work is based on some foundational principles. We strive to:

  • Preserve the ability to run old/historically significant software. This means functionally accurate, sometimes bug-compatible, but not cycle-accurate, simulation.
  • Make it reasonably easy to add new simulators for other hardware while leveraging common functions between the simulators.
  • Exploit the software nature of simulation and make SIMH convenient for debugging a simulated system, by adding non-historical features to the environment.
  • Make it convenient for users to explore old system environments, with as close to historical interfaces, by mapping them to new features that modern host operating systems provide.
  • Be inclusive of people and new technology. It’s serious work, but it should be fun.

Unfortunately in our previous work, we never spent the time to codify how we would deliver on these principles. While that informal structure served us well for many years, as the project grew bigger and more successful we learned that to ensure its longevity, we must add structure.

“The Open SIMH Project” is the result. It was created to be the keeper of and provide formal governance for the SIMH ecosystem going forward. While details of the structure and how it operates are likely to be refined over time, what will not change is our commitment to maintaining SIMH as a free and open-source project, licensed under an MIT-style license.

We hope and intend that all of the past users and contributors will come to recognize that the new organization is in the best interests of the community at large and that they will join us in it. However, this new project is where we will contribute our expertise and time going forward.

Although evolving, we have in place the following resources:

  • A Github “organization” for the project at https://github.com/open-simh

  • A Git repository for the simulators themselves at https://github.com/open-simh/simh

  • The license for the SIMH simulator code base, available here and as LICENSE.txt in the top level of the “simh” repository.

  • The “SIMH related tools” in https://github.com/open-simh/simtools. This is also licensed under MIT style or BSD style open source licenses (which are comparable apart from some minor wording differences).

  • A “SIMH Steering Group” – project maintainers and guides.

  • The conventional git-style process is used for code contributions, via pull requests to the project repository. The Steering Group members have approval authority, although we expect others to be added over time.

We foresee other resources being added in the future as we identify the project’s needs and they evolve.

By formalizing the underlying structure, our operational principles and guidance can best benefit the community. While these are evolving, the current drafts are on this website.

We have used our best judgment in setting up this structure but are open to discussion and consideration of other ideas, and to continuous improvements. Many of us have been part of different projects and understand that past mistakes are real. We have tried to learn from these experiences and apply the collected wisdom appropriately.

We want to hear from the community as we update and refine the operating structure for the Open SIMH project. In its definition, our guiding principles have been and will continue to be: to use a light touch, to try hard to “do no harm,” but at the same time we try to be formal enough to avoid future misunderstandings.

We hope for your patience and look forward to the community’s support as we work to refine the organization and be able to provide this wonderful resource for anyone to use as we continue to evolve the technology provided by the SIMH system.

The SIMH Steering Group
Clem Cole
Richard Cornwell
Paul Koning
Timothe Litt
Seth Morabito
Bob Supnik