Caution: Writing to specific sectors is extremely risky because it bypasses
the Windows NT file handler. The disk's file structure can easily be damaged if
the wrong values are typed.
You must have specified the name of the disk file when you started Debug or in
the most recent Debug n (name) command. Both of these methods properly format a filename for a file
control block at address CS:5C.
Resetting BX:CX before using the w command without parameters
If you have used a Debug g (go), t (trace), p (proceed), or r (register) command, you must reset the BX:CX registers before using the w command without parameters.
Writing a modified file to a disk
If you modify the file but do not change the name, length, or starting
address, Debug can still correctly write the file to the original disk location.
Limitation on the w command
You cannot write an .EXE or .HEX file with this command.
More Information About Debug: W