Iain Stuart evoked the ghost of those old Kaypro luggables (Ran CP/M, if I
recall correctly) that were God's gift to computing a few years back. Well,
if you kept field notes on a Kaypro with five-and-a-quarter-inch floppies,
you had better have paper backup.
 
In order to clarify the data collection thread, let me offer the following
long-term storage considerations:
 
1. Permanence: Is the data medium archival?  Magnetic media are notorous
for being ephemeral.  Some old tape recordings have become brittle. Others
have separated from their emulsions, and then there is the problem of
"bleed" of magnetic images.  A magnetic data file is not archival unless it
is maintained by a data archivist who knows what he is doing.  As for laser
media, we don't know yet, but CD looks promising.
 
2. Data compatibility: Will the data be usable by later programs, operating
systems, and machines?  Is the data format easily read by different
programs?  Relational formats are notoriously difficult to retrieve, if you
don't have the program that created them.
 
3. Media compatibility: Will machines be available five years hence to read
your data?  To answer this question for yourself, retrieve some material
you recorded five or ten years ago.
 
Then there are logistical considerations involved with taking a computer
into the field:
 
1. Power: Any computer will lose the data in its RAM if it loses power.
Therefore any field computer must have reliable, and properly backed-up,
power. There are redundant systems that provide a trickle of power to keep
the RAM alive,and all sorts of precautions you can take. The best insurance
against data loss from power loss is a system that constantly backs itself
up. There are several such schemes.
 
2, Redundancy: If you are dependent upon any device for your fieldwork, you
should carry two of them. If your only shovel breaks, your field day is
over, so you carry two shovels, right? Well, if your data recording system
goes south, which is more likely, you should have a backup. A paper record
would be the best possible backup.
 
3. Data security: You can't just throw the diskettes into the glove box.
Any magnetic media must be properly protected.  I wouldn't want to try to
read a diskette that had been knocking around, naked, in my field vehicle.
 
Many issues in this second group have been addressed by land surveyors as
they have adopted field data capture, but I am distressed by some postings
on this thread that don't seem to take into account the nature of
archaeological data.  If a land surveyor or engineer has a problem with
recovered data, he can always go back into the field and double check.
Surveyors do this frequently. We can't.
 
When we come home from a site, we frequently carry unique data in our
files, and the site is gone. This is the destructive nature of what we do.
Therefore, the precautions that protect surveyors' data may not be
sufficient for us.