When I format the flash drive with a image of MS-DOS and Windows 1.01, which is 1.44 MB, in Rufus 2.18 portable, the USB drive shows as 1.44 MB to match the floppy disk image. I am planning to add other operating systems and games which will exceed the free space limit of ~200 KB.

2 Answers 2


This is because Microsoft limited the boot disk size to 1.44 MB for optimum compatibility with largest number of BIOSes available. I think this is hard limit regardless of which MS-Dos version you're using. Not sure if this applies to bootable CD iso, though.

If it's MS-Dos 6.22 then the only way to use more of the USB space is to create more partitions. They still can be 2GB max (another Microsoft limit) each and even then you're limited to max 8GB of the total drive capacity. This should be doable by using disk manager of your OS ( in Windows it is Disk Manager or Diskpart command-line utility).

You can use space over 8GB only by using different OS or by specific software.

That is why, back in the old days if one wanted dual-boot, i.e. Dos(windows) and linux, on one PC then windows would be installed first and then Linux would install in space over 8GB and would took over the boot.


Well, if you want to add more OS installers, you can always make new boot partitions on that next to the MS-DOS one. The MS-DOS boot partition will never be bigger than 1.44MB on a non-optical disk. For games, you can create its own separate partition that doesn't contain bootable code, eighter in FAT32 or if you want that partition to be accessible in DOS, in FAT16. Don't forget that MS-DOS may want to limit you in the volume size of said partition. Linux partition may be ext4, its native filesystem. Then when you connect the USB stick, you're then presented with multiple options in a boot menu. The actual boot options may differ in favour of hardware used, but you should be able to choose which OS you want to boot from.

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