Two utils added: FULLNULL.COM creates NULLFILE.$$$ and writes
0F66FF99Fh-pattern to it in 64 kB blocks until the disk is full.
NULLCHK.COM verifies that file. If errors are detected, number of
flipped bits is displayed. Also errors at bit positions 0-31 is displayed.
Errorlevel 0 means Data OK, 255 means Read errror, 1 means NULLFILE.$$$
not found.

Another way to test your hd is to run 'Safbench O:M' under Win95
(swapping means reading/writing hd, but actually it's MOSTLY just seeking
tracks). Be patient if you decide to do that!
