Jeff Rothenberg's Digital Longevity Page


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The Rosetta Stone vs. obsolete digital storage media (© Jeff Rothenberg 1994)

[under construction]

(Under repair & updating as of Oct. 2026... Please be patient)

What is this webpage?

This is a collection of references on the subject of digital longevity (defined below). These include my own writings on the subject as well as links to many other relevant publications, organizations, projects and activities. This is an ongoing and necessarily incomplete collection, and I welcome additions, corrections, and comments. I would especially appreciate references to documented cases of loss or corruption of digital documents, data, or other artifacts and to examples of the use of migration, emulation, or other digital preservation techniques, whether or not successful.

What is digital longevity?

Anyone who has used computers for a decade or more is aware that the media on which digital information is stored have very short physical and obsolesnce lifetimes compared with high-quality paper, photographic film, or painted canvas (not to mention stone tablets). Yet beyond this storage media problem, every digital artifact (whether it is a document, data, image, music, art-work, game, program, or entire system) is encoded in a binary format of some kind—a stream of bits. This bitstream must be interpreted by some process—typically a computer program—that understands the artifact's format in order to "render" it into a form that humans can perceive (read, view, hear, interact with, use, etc.). But digital formats and the programs that render them become obsolete very quickly, as do the computers on which they run, making it unlikely that our grandchildren will be able to access and use the digital artifacts that we are currently creating, unless we take appropriate action. The papers and reports referenced on this page discuss the dimensions of this problem and analyze a number of potential solutions, including migration into successive new formats, the re-encoding of artifacts into universal formalisms, and the future emulation of obsolete computers to allow an artifact's original rendering software to be run indefinitely.
 
Terminology note: some organizations and authors use the term simulation as a synonym for emulation in the context of digital preservation. Having spent much of my career as a computer scientist building simulation models for various purposes (other than preservation), I consider this a misuse of the former term. A simulator is a program or device that shows its user what the system or thing it is simulating would do but does not actually do it. For example, with a few rare exceptions, an airplane simulator does not fly. That is, a simulator has an informational purpose. In contrast, an emulator actually does whatever the system or thing it is emulating would do, so its purpose is instrumental. Nevertheless, the distinction between the two terms is blurred in many contexts (for example, "simulated leather" behaves like leather for most purposes, rather than simply showing us how leather would behave), and this fuzziness creeps into the digital preservation domain on occasion, causing (in my opinion) unnecessary confusion.

*** Note on accessing my references

Given the subject matter of this page, it is a true example of irony (unlike the common misuse of that term to refer to almost anything surprising or annoying) that the URLs in the citations below—as is the case for many World Wide Web references—tend to become invalid over time, as the sites that once provided them are renamed, reorganized, rehosted, abandoned, or decommissioned. While attempting to keep up with this continuous "link rot" I also offer a local copy of each referenced document wherever possible, as a fallback. In all cases, I try to provide proper citations and links to the authors and/or publishing organizations, but I cannot guarantee that any such links will remain valid.

My major publications (with references) on this subject are:

My article "Ensuring the Longevity of Digital Documents" [Rothenberg, J., Scientific American, January 1995 (Vol. 272, Number 1), pp. 42-7 (International Edition pp. 24-29)] gives an overview of the problem and proposes a solution based on emulating obsolete computers in the future (available from the SciAm archives or here). An expanded version of this article is also available at the Council on Library and Information Resources (CLIR) website or here.

Avoiding Technological Quicksand: Finding a Viable Technical Foundation for Digital Preservation (html or pdf) was produced for the Council on Library and Information Resources (CLIR) in January 1998 and provides an in-depth discussion of a range of proposed preservation approaches (ISBN 1-887334-63-7). A PDF version is also available.

My paper "Preserving Authentic Digital Information" discusses the question of what constitutes an authentically preserved digital document or record. The paper appears on pp. 51-68 of the May 2000 report Authenticity in a Digital Environment (html or pdf), published by CLIR (ISBN 1-887334-77-7). This paper is also available here.

Using emulation to preserve digital documents (pdf) published in 2000, describes work done with the Dutch Royal Library (the Koninklijke Bibliotheek) on the use of emulation to preserve digital documents in the deposit library context (ISBN 906259145-0). The report and the project that produced it are described at the Dutch Library's site.

My reports An Experiment in Using Emulation to Preserve Digital Publications, published in 2000 by the Dutch Royal Library (the Koninklijke Bibliotheek, or KB) [ISBN 9062 59 1442] (also available in an earlier PDF version) and Using Emulation to Preserve Digital Documents discuss the use of emulation to preserve digital documents in the Dutch digital preservation testbed. The Deposit System for Electronic Publications (DSEP) project that spawned this work (described in this report) was part of the Networked European Deposit Library (NEDLIB) effort (also available as PDF). A related testbed report on migration discusses the alternative use of migration for preservation.

Further exploration of emulation was also undertaken by the EU's KEEP Project (described in more detail here), and discussed in more depth in this report. See also this Tessella white paper on Digital Archiving and Tessella's Digital Curation tools (as of 2013) (also available here).

For a report on the experimental use of emulation for digital preservation at the Dutch national library (the Koninklijke Bibliotheek, or KB), see Emulation for Digital Preservation in Practice: The Results (The International Journal of Digital Curation, Issue 2, Volume 2, 2007), also available here. For additional discussion of the Dutch Dioscuri emulation effort, see Dioscuri on sourceforge and Emulation_report_KBNA_2005_en.pdf (also available here) and Modular emulation as a viable preservation strategy (also available here). For more detail about the Dioscuri system, see the Dioscuri manual.

Carrying Authentic, Understandable and Usable Digital Records Through Time (pdf) which I co-authored with Tora Bikson in 1999 for the Dutch National Archives and Ministry of the Interior, investigates issues surrounding the preservation of digital archival records. This report produced the design for a preservation testbed that was subsequently implemented. See also this pre-publication draft of my white paper on emulation. See also the following papers and reports describing the related: Planets Testbed: Science for Digital Preservation (also available here and Planets Testbed, DCC (The Digital Curation Centre) (also available here.

The 80+ page paper "Scholarly Communication and Information Technology: Exploring the Impact of Changes in the Research Process on Archives" (which I co-authored with Avra Michelson who was then at the U.S. National Archives) appeared in The American Archivist in 1992. It is available as a single large (6MB) scanned PDF file or as a set of separate PDF sections. I provide an overview of then-current and future information technology and predict its impacts on archival research in the Overview of Information Technology section of this paper. My first published proposal of the emulation approach to digital preservation appeared in the Conclusion and Recommendations section of this paper (Part II: Establishing a Strategy for the Future Usability of Electronic Records, p. 297, ff.), although it may be difficult to recognize. The paper is also available as RAND reprint RP187 (DOI: https://doi.org/10.7249/RP187).

My paper "Preservation of the Times" [which appeared in The Information Management Journal, March/April 2002, Vol 36, No. 2, pp. 38-43. ISSN 1535-2897 (ARMA International)] compares two approaches to using emulation for preservation.
 
The Erl King gives an overview of the renewal of a 1980s analog/digital interactive video artwork by Grahame Weinbren and Roberta Friedman. This work was undertaken by the Berkeley Art Museum and Pacific Film Archive (BAM/PFA) Archiving the Avant-Garde project (also available here), a consortium effort supported by the National Endowment for the Arts. The renewed Erl King was the centerpiece of the Seeing Double exhibit at the Guggenheim Museum in New York, March 2004. My introduction to the Erl King overview (same link as the first in this paragraph) discusses the technical options for renewing this piece. A report on this project is given in Seeing Double: Emulation In Theory And Practice—The Erl King Case Study (by Caitlin Jones), and my report Renewing-the-Erl-King (which was also published in The Millennium Film Journal (MJF) "Hybrids", Issue Nos. 45/46 (Fall 2006), pp. 20-51) provides a deeper—but minimally technical—discussion of the issues and implementation choices involved in this effort. Related information about this project is given at the Guggenheim's Variable Media Initiative page, and the Daniel Langlois Foundation's site. Further discussion of the Erl King renewal project is presented in this report on the Erl King project (also available here) and in this essay by Grahame Weinbren (also available here).

The Council on Library and Information Resources (CLIR) funded the 1-hour 1998 PBS film Into the Future: Information in the Electronic Age to publicize the problems of digital preservation. The film (discussed here and directed by two-time Academy Award winning documentary filmmaker Terry Sanders) presents a number of "talking heads" (including myself) discussing the problems of preserving digital information. A short initial clip of this film (or the entire film, with appropriate access), can be watched here.

The computer gaming community was an avid adopter of emulation as a way of preserving the look-and-feel of early computer games. This 2014 entry in the blog THE SIGNAL—Digital Happenings at the Library of Congress (also available here), by Euan Cochrane, Digital Preservation Manager at Yale University Library, discusses Yale's experiences with the Emulation_as_a_Service_(EaaS) framework.

Additional substantive resources:

This 2010 report by Kam Woods and Geoffrey Brown of the School of Informatics and Computing at Indiana University (also available here) discusses the practical contextual knowledge required to successfully use legacy software via emulation.

For a 30-year hindsight view of the digital preservation work of the Dutch National Library (KB), see this retrospective analysis by Inge Hofsink (also available here).

For a 2025 review of the use of emulation in digital preservation, see An Overview of Emulation as a Preservation Method (also available here). Key references in this paper include Satyanarayanan, Mahadev. 2018. "Carnegie Mellon Is Saving Old Software from Oblivion (IEEE Spectrum)" (also available here); this 2008 RAND-Europe report "The uncertain future of saving the past" by Stijn Hoorens and Jeff Rothenberg (also available here), and Slats, Jacqueline. 2003. "Emulation: Context and Current Status." Digital Preservation Testbed White Paper. Netherlands National Archives (currently unavailable); [plus more??]

Additional (though often less substantive) references:

The majority of the following references are (in my opinion) disappointingly shallow in their discussions of the technical issues involved in preserving digital artifacts, focusing more on abstract process and policy recommendations than on concrete techniques. I have noted over the past several decades in this field a tendency to "look for the car keys under the streetlamp" by putting more effort into developing metadata formats and organizational strategies than experimenting with actual digital preservation techniques. In particular, many of these references briefly mention migration and emulation as potential methods of preserving digital material, but they shy away from explaining what these would involve or how they might work in practice, or comparing their ability to enable the meaningful use of digital artifacts even in the near— let alone distant—future. I therefore provide them more as an indication of what is not being done than what is. However, I have marked with leading asterisks those that contain (again, in my opinion) at least some substantive material.

The British Library (BL) provides a number of resources, including BL: Digital Collection Management Policy Framework (Part 3: Digital Preservation (overview only) and Selection of Preservica for large-scale Digital Preservation program. Preservica in turn provides additional technical references, including: Digital Preservation Overview and Automated File Format Preservation, which includes a cursory discussion of emulation (also available here) [NOTE: Preservica calls emulation "simulation" as discussed in my Terminology Note above.]

Library of Congress Digital Preservation

U.S. National Archives (NARA) Digital Preservation

Tiered Community Recommendations For Content Authenticity And Provenance (TCR4CAP)

Dutch National Library (KB) Digital Preservation Overview (Download the latest version of the KB's Dioscuri modular emulator here)

Dutch National Archives Website Archiving Guide

The International Internet Preservation Consortium (IIPC)

The Internet Archive.

The national library of France (The Bibliothèque nationale de France [BnF]) is a member of The Digital Preservation Coalition (DPC), which discusses What is a record (and why do we need to preserve them)? See also BSI.knowledge Management of Records Code of Practice.

*** The Guggenheim Museum in New York was an early supporter of the acquisition and preservation of digital art. It was a partner in the NEA sponsored project Archiving the Avant-Garde (also available here). In addition its work described in the Erl-King references above, the Guggenheim continues to be actively involved in the preservation of computer-based (digital) art via projects including its Conserving Computer-Based Art Initiative (CCBA), and its Time-Based Media & Media Conservation Lab.

*** An undergraduate paper comparing three approaches to conserving Time-Based Media is presented in the University Of Denver's Strategies In Time-Based Media Conservation: An Evaluation of Three Institutional Approaches (DUURJ Archive, Vol. 5, Iss. 1 (2024), by Mya Vander Pol (also available here).

MoMA offers cursory advice on the preservation of digital artworks in Making Practice Practical: Developing Digital Preservation for Storage of Artworks at the Museum of Modern Art (also available here), ?OR? ?HERE?. See also resources on MoMA's Media Conservation Disk Imaging page, including this paper, as well as this one, which includes a discussion of Emulation as a Service (EaaS).

The Getty offers a disappointingly vacuous discussion of Evolution of Digital Preservation (DP) at Getty (also available here) and this equally disappointing paper on Preventing Digital Decay (also available here)

For an example of the impact of this early research on the use of emulation for digital preservation in the library context, see this discussion at eduKate Singapore.

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