Partitions

A hard disk can be separated into various partitions. Every partition functions as if it were a separate hard disk. Then, one hard disk can be separated into two partitions to have two operating systems on it. Every operating system uses its partition according to its preference without disturbing the other. On this way the two operating systems can co-exist peacefully on the similar hard disk.

Floppies are not partitioned. There is no technical reason against this, but because they are so little, partitions would be useful only very rarely. The CD-ROMs are also not partitioned, also because it's simpler to use them as one big disk and there is seldom a required to have various operating systems on one.