The tail-end of an interesting
conversation about emulation, stimulated by the previous email about the National
Archives of the
*****************************************
Henry,
I agree that the term
"emulation" is confusing as stated.
Furthermore, there is no
such thing as a universal emulator.
Each machine, including each
device that might be attached to each machine, would require its own emulator.
You'd need separate
emulators for an IBM 704 and an IBM 709, but you might be able to use a single
emulator for both a
709 and a 7090. You'd also
need separate emulators for each type of I/O device that might be attached to
each machine.
Furthermore, some devices,
such as tape drives and card readers, could be attached to multiple machines,
such a 7090 or a 1401.
It should be possible to run
the same device emulators with multiple CPU emulators -- but that would require
some conventions for how they are interconnected.
And then you'd need some
kind of hardware support for old media, such as punched cards and magnetic
tape. And there would have to be very different converters for the many
different kinds of card and tape formats.
The entire idea of emulation
has to be explained in great detail and some kind of hardware is necessary to
deal with the various kinds of media.
John
___________________________________________________________
> It seems to me that
this statement needs to be improved, in that it does not make clear in its
opening statement what is to be emulated.
>
> I presume that what is
to be emulated is a Turing-equivalent digital computer (or an extension of such
a machine, such as a machine with multi-tasking), following Raymond Lorie's
idea of almost a decade ago, but I am uncertain whether this or something else
is in fact intended. However, this possibility is not hinted at until the
fifth sentence, and then the relationship of the "EVC" there
mentioned to the word "emulation" in the first sentence is not
explicit. If it is Lorie's idea, why not use the same name that he used, viz.,
"UVC" = "Universal Virtual Computer"?
>
> The problem is that a
computer scientist who has not been following discussions of digital
preservation woudl find it very difficult to understand what the statement is
saying, and that one "in the business" would not understand with
confidence what relationship to Lorie's work was intended, if any. Perhaps
citation(s) would help the difficulty.
>
> Putting things a bit
ridiculously, "emulation" in the first sentence might refer to emulation
of a high performance automobile, or a child's emulation of an older sibling.
>
> Best wishes, Henry
>
> H.M. Gladney, Ph.D. http://home.pacbell.net/hgladney
(408)867-5454
>
> P.S. The statement has
other weaknesses of language. E.g., it uses the word "advantages" in
its opening phrase. One must inquire, "Advantages over what?", or
did you mean to say "a number of unique virtues" or something like
that?
>
> From: Remco Verdegem [mailto:[log in to unmask]]
> Sent: Friday, November
17, 2006 5:51 AM
> To:
[log in to unmask]; [log in to unmask];
> Subject: [Norton AntiSpam]
[padiforum-l] Digital preservation using
> emulation
>
> *** Apologies for
cross-posting ***
>
>
>
> In 2005, the Nationaal
Archief of the
>
>
>
> At the end of the
expert meeting the participants formulated and endorsed a statement concerning
the use emulation for digital preservation purposes:
>
>
>
> "Emulation is a
viable preservation strategy that has a number of unique advantages:
>
> *
> It preserves and
permits access to each digital artifact in its original form and format; it may
be the only viable approach to preserving digital artifacts that have
significant executable and/or interactive behavior.
> *
> It can preserve
digital artifacts of any form or format by saving the original software
environments that were used to render those artifacts. A single emulator can
preserve artifacts in a vast range of arbitrary formats without the need to
understand those formats, and it can preserve huge corpuses without ever
requiring conversion or any other processing of individual artifacts.
> *
> It enables the
future generation of surrogate versions of digital artifacts directly from
their original forms, thereby avoiding the cumulative corruption that would
result from generating each such future surrogate from the previous one.
> *
> If all emulators
are written to run on a stable, thoroughly-specified "emulation virtual
machine" (EVM) platform and that virtual machine can be implemented on any
future computer, then all emulators can be run indefinitely.
>
>
> In order to develop a
practical, off-the-shelf preservation strategy based on emulation, a number of
additional steps are required, including:
>
> *
> Create and
demonstrate example emulators suitable for long-term preservation.
> *
> Develop fidelity
criteria for each behavioral dimension of digital artifacts (e.g., display,
sound, timing) and develop validation test suites, which evaluate these
criteria and verify that the logical behavior of an emulator matches that of
its target computer.
> *
> Research and
develop device-independent input/output mechanisms to allow unmodified programs
to behave and interact appropriately with users on future computer platforms.
> *
> Develop methods
for capturing and preserving contextual information describing the logical,
physical, organizational, and social environments in which digital artifacts
were originally used, as well as documentation describing how they were used
and what they were used for.
> *
> Develop methods
for describing, managing, and automatically interpreting information about the
versions and configurations of software and hardware needed to render digital
artifacts under emulation.
> *
> Define and
develop a long-lived emulation environment to enable emulators to be run
indefinitely. This environment could be equivalent to an emulation virtual
machine (EVM) platform, though it may be implemented as a long-lived
programming language along with a stable set of program library facilities.
This environment should:
>
> - Enable using
old digital artifacts by running their original
> software under
emulation on unforeseen future computers;
>
> - Provide
automatic configuration of emulators, software
> environments, and
applications to render old digital artifacts;
>
> - Provide
documentation, active user help, and/or automatic
> reinterpretation of old
interaction modes into future equivalents, to
> help future users
utilize old digital artifacts under emulation;
>
> - Provide
mechanisms to facilitate (or, ideally, automate) the future generation of surrogate
versions of digital artifacts directly from their original forms.
>
> *
> Develop
network-based services for providing remote access to old digital objects via
emulation, without requiring remote users to load and run an emulation
environment on their local systems."
>
>
>
> This statement is
endorsed by all participants of the Emulation Expert Meeting:
>
>
>
>
>
> Raymond van Diessen,
IBM Netherlands N.V., The Netherlands
>
> Hans Hofman, Nationaal
Archief of the
>
> Jeffrey van der Hoeven,
Koninklijke Bibliotheek, The Netherlands
>
> Vincent Joguin, ACONIT,
France
>
> Bram Lohman, Tessella
Support Services plc., The Netherlands
>
> Gregory Miura,
Bibliothèque
>
> Bill Roberts, Tessella
Support Services plc., The Netherlands
>
> Jeff Rothenberg, RAND
corp.,
>
> Jacqueline Slats,
Nationaal Archief of the
>
>
> Tobias Steinke, Die
Deutsche National
>
> Dirk von Suchodoletz,
>
> Remco Verdegem,
Nationaal Archief of the
>
>
>
> Richard Wilkinson,
Tessella Support Services plc.,
>
> Hilde van Wijngaarden,
Koninklijke Bibliotheek, The Netherlands
>
>
>
> This statement together
with a short overview and presentation slides will be made available on the
project websites of Digitale Duurzaamheid (Digital Longevity) and the
Koninklijke Bibliotheek:
>
>
>
> http://www.digitaleduurzaamheid.nl/index.cfm?paginakeuze=327
>
> http://www.kb.nl/hrd/dd/dd_projecten/projecten_emulatie-en.html
>
>
>
>
>
> Emulation project -
background information
>
>
--------------------------------------------------------------------
>
> The Koninklijke
Bibliotheek (KB) and the Nationaal Archief of the
>
>
>
> In April 2005 the
Nationaal Archief and KB started the emulation project and chose Tessella
Support Services plc. to develop an emulator which should be flexible and
durable for the long term. Key issue in this development is the conceptual
model of the Modular Emulator, which was defined by the KB in cooperation with
Jeff Rothenberg at the end of 2004. Jeff is also joining the project team
during design and development of the emulator.
>
>
>
> More information: see
references above.
>
>
>
>
>
>
>
>
**********************************************************************
>
***************************************************
>
> Remco Verdegem
> Senior Advisor Digital
Longevity
> Project Manager Modular
Emulation
> Nationaal Archief of
the
> e:
[log in to unmask]
> t: +31 (0)70 331 55 43
> w: www.digitaleduurzaamheid.nl
>
Executive Secretary
Digital Preservation Coalition
Innovation Centre
Heslington
YO10 5DG
e: [log in to unmask]
t: +44 (0) 1904 435 362