With the Dual Boot feature (available in this and earlier versions of the OS/2 operating system), users can add OS/2 2.0 to a partition that already contains DOS. Users then can shut down one operating system and switch to the other one when necessary.
If a DOS partition has sufficient space, a user can install OS/2 2.0 without repartitioning the hard disk.
The primary partition must be large enough to accommodate both DOS and the OS/2 operating system. (Note that the partition size required by OS/2 2.0 depends upon which features the user installs.) When planning partitions, calculate the size of both operating systems and also the growth of a swap file. (A swap file contains segments of a program or data temporarily moved out of main storage.) See "Swap File."
For example, if DOS currently takes up 4MB and the user is going to install all features of OS/2 2.0 (which require 30MB), the primary partition should be at least 40MB. (This will allow room for a swap file.) If the user intends to place applications and data in the primary partition, the partition will have to be large enough to accommodate those also. If the existing primary partition is not large enough, use the DOS FDISK command to change the hard disk setup. Follow the instructions in the DOS documentation.