http://astrosurf.com/buil/d70v10d/eval.htm

Text in French, but with inline English translation. Interesting observation:

"[...] the internal firmware applied a median like
filter to the three layers of the image for erase hot
pixels (local intense thermal signal). This processing
is not mentioned in Nikon documentation [...]
the RAW format of Nikon D70 is not a true raw format
[...] an image which would reflected the outgoing
signal of a CCD sensor [...]"

There is, however, a blunt workaround.