MS-DOS sürüm 2.0-6.0 içinde SYS.COM gereksinimleri

   IO.SYS and MSDOS.SYS
				

   IBMBIO.COM and IBMDOS.COM
				

   sys c:
   copy command.com c:\ 
				

   Version   Description of Changes
   -------   ----------------------
   3.3       MS-DOS allows system files to be noncontiguous
             (fragmented). However, the system files must still occupy
             the first two directory entries, and the first three
             sectors of IO.SYS (or IBMBIO.COM) must be located
             in the first three sectors of the disk data area.
   4.0       When either or both of the following conditions are met,

             - The first three sectors are allocated, and not to the
               first system file, but there is enough free space on
               the drive to copy the system files over.

             - The SYS command does not recognize the first two files
               in the root directory as system files, but the root
               directory is not full.

             the SYS command will, if necessary, move the first two
             directory entries and/or the data located in the first
             three sectors of the disk to another location, and then
             copy the system files. This allows you to use SYS to
             change from PC-DOS to MS-DOS; however, the PC-DOS system
             files will not be deleted.

             The SYS command will execute properly in earlier versions
             of MS-DOS if the drive formats are compatible; however,
             this is not guaranteed in all circumstances. If it is
             impossible to boot MS-DOS 4.0 before running SYS, using
             the SYS command on a floppy drive is the safest course of
             action.

   5.0       MS-DOS 5.0 SYS.COM recognizes both the Microsoft system
             file names (IO.SYS and MSDOS.SYS) and the IBM system file
             names (IBMBIO.COM and IBMDOS.COM) as system files. So,
             when using the SYS command to transfer MS-DOS to a system
             that booted with PC-DOS, IBMBIO.COM and IBMDOS.COM will
             be deleted.

             The first three sectors of IO.SYS do not need to be in
             the first three sectors of the data area; however, they
             must be contiguous.

             SYS copies COMMAND.COM to the destination disk.
             An optional second parameter to specify the source of the
             system files is supported when running in MS-DOS 5.0.

             Again, running the SYS command without booting MS-DOS 5.0
             is not recommended. If you cannot boot MS-DOS 5.0, use
             the SYS command on a disk in drive A, and use that disk
             to boot MS-DOS 5.0.

   6.0       SYS copies DBLSPACE.BIN to the destination disk, as well
             as copying IO.SYS, MSDOS.SYS, and COMMAND.COM.