Booting the old style...

First you need to partition your hard disk and make your partition active. using FDISK. The BIOS will look for this partition.

Later you need to format your partition with the /S option, not all the DOS versions support this switch.

Otherwise you could format your hard disk and next execute SYS c: this will copy IO.SYS, MSDOS.SYS and COMMAND.COM and point the first sector of the partition to IO.SYS.

You need to do this to been able to boot from the hard disk, if you just copy the files it will not boot.