>Does anyone know how DOS generates serial-numbers for floppies?

Here are the details of the volume serial number:
 
The first part of the serial number is equal to the sum of the time
(seconds and hundredths of a second) and the date (month and day);   The
second part of the serial number is equal to the sum of the time (hours
and minutes) and date (year), where all numbers are in hex.  For
example, if the diskette is formatted at 8:32:43.65 on 7/21/1991, the
first part of the serial number will be 2B41+0715, or 3256;  the second
part of the serial number will be 0820+07C7, or 0FE7.

Hope that this is of some help.
Ray