10. A QUESTION OF
REPRESENTATION
=
“I am the wisest
man alive, for I
know one
thing, and that
is that I know
nothing.”
-Plato
10
=
00100010010010010010000001100001011
01101001000000111010001101000011001
01001000000111011101101001011100110
11001010111001101110100001000000110
11010110000101101110001000000110000
10110110001101001011101100110010100
10110000100000011001100110111101110
01000100000010010010010000001101011
01101110011011110111011100100000011
01111011011100110010100100000011101
00011010000110100101101110011001110
01011000010000001100001011011100110
01000010000001110100011010000110000
10111010000100000011010010111001100
10000001110100011010000110000101110
10000100000010010010010000001101011
01101110011011110111011100100000011
01110011011110111010001101000011010
01011011100110011100101110001000100
00011010000101000101101010100000110
1100011000010111010001101111
11. BIT ROT:
THE DEGRADATION OF BITS
OVER TIME
"I am the wisest
man"alive, fob I know one
thing, and that is that I onow
nothing."
-Plato
-Plato
Original Text
3 Bits Corrupted
11
“I am the wisest man
alive, for I know one
thing, and that is that I
know nothing.”
19. 2. DOCUMENTATION & METADATA
• File Type
Word Doc
• Software Version
MS Word 2010
File Name
File Size
Number of Words
Total Editing Time
Creation Date
Last Modified
Last Printed
User Name
19
•
•
•
•
•
•
•
•
20. 3. MIGRATION
20
• The transfer of
a bit stream
(the 1s and 0s)
from one
medium to
another.
24. 4. EMULATION
Creates an
environment that
„tricks‟ the software
into functioning as if
it was in its original
computing
environment.
24
Similar to impersonation.
25. EMULATION &
THE GAMING COMMUNITY
"The Old Version Flickers More": Digital Preservation from the User's
Perspective
25
http://archivists.metapress.com/content/1765364485n41800/
27. 5. HASHING/CHECKSUMS
How they work:
An algorithms „reads‟ a digital object and, based upon the 1s
and 0s that make up that object, produces a unique alphanumeric string of characters that represent it.
27
What that means:
Checksums are very effective tools in determining if a digital
object has been corrupted (assuming you have the original
checksum to compare it to).
39. FILE SIGNATURES/MAGIC NUMBERS
• Every file type has a digital „finger print‟
near the beginning of its code, sometimes
called a „signature‟ or „magic number‟.
39
• In a hex editor, you can read the
hexadecimal notation of the file and
identify its magic number, then look up
that number to identify the file type.
41. IF YOU HAVE QUESTIONS
ABOUT DIGITAL PRESERVATION
41
THE LIBRARY IS HERE TO HELP
42. Questions?
Shea Swauger
Data Management Librarian
Morgan Library, 210E
shea.swauger@gmail.com
42
This presentation is available at http://www.slideshare.net/SheaSwauger