The advantages of this system are that it is simple and easy to implement and it is very fast. Most large computers and many modern personal computers use a much more complicated and flexible method. Taking the cue from virtual memory pages, these systems break a file into sector-sized pieces and store them anywhere on the disk where there is free space. In order to know which sectors are part of which files, the operating system maintains either tables relating sector addresses to positions in the file, or it chains together the sectors in linked lists. The directory entry that stores the file's name also stores the address of the first sector of the file. To find the second sector, the operating system reads the first sector and decodes part of the 512 bytes as the pointer to the next sector.