IO.SYS and MSDOS.SYS-or-
IBMBIO.COM and IBMDOS.COMA disk can only be made bootable in MS-DOS by using the FORMAT /S,DISKCOPY, or SYS command.
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.
Article ID: 66530 - Last Review: 05/12/2003 21:03:14 - Revision: 2.0