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DigiCULT
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Info
8
PAUL WHEATLEY FROM THE CAMILEON
PROJECT AT THE UNIVERSITY OF LEEDS
LIBRARY SPOKE TO DIGICULT.INFO
ABOUT THE TECHNIQUES AND CHAL-
LENGES OF EMULATING OBSOLETE
SOFTWARE.
What led to the CAMiLEON project
being set up?
A
t the time that CAMiLEON was
formed there was an unresolved
debate about the role of emulation in digi-
tal preservation. Some thought that emula-
tion would simply not work in practice
and that migration (changing data files into
new formats as necessary so that they can
be used by new software) would be the
answer. A minority argued that migration
would not be sufficiently accurate in the
long term, and that the only way of being
sure that your preserved objects have really
survived over time is to see them emulated
in their original environment. Overall,
emulation was viewed with a high degree
of scepticism. So CAMiLEON was pro-
posed as a way of getting to the bottom of
the emulation question and testing if it
could work in practice.
O
f course, emulation has been used
in many aspects of computing for
decades.What was needed was a strategy
to give longevity to emulation implemen-
tations and hence make it practical in a
preservation context.We found that emula-
tion and migration, rather than being
opposing sides to the preservation coin,
actually work very well in partnership.
One solution does not satisfy every
eventuality.
Why was it important to tackle the
BBC Domesday project?
B
BC Domesday is a fascinating
resource and a wonderful story of
vision and innovation but it has acted as a
prime example of the digital preservation
data. Current media such as CD-ROMs
are likely to be just as short-lived as the
rapidly changing media of the past: paper
tape, punched cards, magnetic tape (e.g.
QIC 24), 8" floppies, to name but a few
examples.Therefore, to avoid obsolescence
of both data and emulation software in
turn, the CAMiLEON team emphasised
media-neutral, platform-independent for-
mats crucial for accurate and efficient
preservation over time.
A
Windows PC version of the
Domesday project, provisionally
known as `1986 Domesday Community',
presents the contents of one of the
Domesday laserdiscs and is now available
for visitors to use in the public reading
rooms at the National Archives at Kew,
Surrey (http://www.nationalarchives.
gov.uk/).
C
AMiLEON are currently seeking
funding to develop their demonstra-
tor into a system to serve Domesday to the
public (subject to IPR permissions).
T
he BBC Domesday project encapsu-
lates many difficult issues relating to
the preservation of an interactive system: a
huge amount of multimedia data, techno-
logical complexities, the IPR issues and
the need for data longevity so that it can
provide a useful historical and sociological
resource for the future.William the
Conqueror's Domesday Book is an invalu-
able document for understanding the past
and it must be ensured that digital archives
in both linear and interactive formats can
ideally also be accessed 900 years from now.
T
he Domesday Book Online can be
found at: http://www.domesday-
book.co.uk/ Further information about
BBC Domesday: http://www.pro.gov.uk/
about/ preservation/digital/domesday/
default.htm Andy Finney's (ATSF) report
on Domesday: http://www.atsf.co.uk/dot-
text/domesday.html
communication and the many functions of
the laserdisc player. In other words, knowl-
edge of how the original system worked is
encapsulated in the emulation software.
Together with the abstracted data of the
BBC Domesday project, this software pro-
vides a record of the original system and
gives an accurate reproduction of almost all
the original functionality.
I
n a separate project, Adrian Pearce
from LongLife Data Ltd designed a
new application that allows new views of
the BBC Domesday data. For example, the
interface can show a map of an area and its
accompanying text in the same window,
which was not possible on the lower reso-
lution screens of the original BBC com-
puters. Adrian worked to understand and
partially rebuild the original hardware and
collaborated with Jeffrey Darlington from
The National Archives (previously the
Public Records Office) and Andy Finney
of ATSF (http://www.atsf.co.uk) one
of the original BBC Domesday team
to incorporate digitised versions of
the original analogue film tapes held
by the BBC.
T
he CAMiLEON team managed to
obtain access to a semi-working
Domesday system (donated by the School
of Geography at the University of Leeds)
and transferred data from the laserdiscs as a
byte-stream readable by modern hardware.
This information totalled around 70
Gigabytes per disc side. Both of these sys-
tems employ the original byte-streams and
formats (e.g. data structures) and fulfil dif-
ferent needs; some users require new ways
to access the data, while others will want
to see it in its original context.
I
n making data accessible it was, of
course, imperative not to fall into the
same trap as in 1986 and to understand
that a crucial part of digital preservation is
not simply maintaining a copy of the data
but maintaining a means of accessing that