Final Year Project: Using Linux Filesystems Under Windows   Chris Bryden BEng. Electronics and Software Engineering    School of Computer Science   University of Birmingham 5 Within  a  partition  the  individual  sectors  are  located  by  a  single  number, known as the ‘logical sector’ number. The CHS reference could still be used, but the single figure is easier to handle. The numbering starts form zero with the first sector of the partition, this sector is known as the ‘boot sector’ of the partition as it contains a small piece of code used to start the operating system.   Logical    sector    numbers    are    obtained    by    numbering    each    sector sequentially  starting  from  track  0,  head  0,  sector  1  (logical  sector  0)  of  the partition and continuing along the same head, then to the next head until the last sector on the last head of the track is counted. Thus, logical sector 1 is track 0, head  0,  sector  2;  logical  sector  2  is  track  0,  head  0,  sector  3;  and  so  on. Numbering then continues with sector 1 on head 0 of the next track.   Converting  the  logical  sector  number  of  a  partition  to  an  absolute  CHS reference  is  a  two  stage  process,  firstly  the  offset  of  the  start  of  the  partition (start_sect) has to be added to the logical sector number, this gives an absolute logical  sector  number.  This  number  is  then  converted  to  a  CHS  reference.  As explained in the previous section, the sector can now be read from disk.