DOS 3.3 was created when hard disk drives were only a dream for
microcomputers. Thus, DOS 3.3 and previous versions understand only the 140K
5.25-inch disks. DOS 3.3 does not understand the 3.5-inch disk and
hard-disk environments. When hard disks did appear for the Apple II family
and DOS 3.3 was still the operating system of choice, individual hard-drive
manufacturers devised independent schemes for dividing their products into
multiple 140K volumes so DOS 3.3 could work with the hard drives. ProDOS
was created to overcome the limits that DOS 3.3 imposed on storage volumes.
GS/OS would require a File System Translator (FST) to recognize the
5.25-inch disks of the DOS 3.3 operating system. However, the FST would be
of no assistance in providing DOS 3.3 partitions on a hard disk, because the
lack of hard-disk support is a limitation of DOS 3.3 itself, not the FST.
To use DOS 3.3 applications on an Apple IIGS requires restarting from a
5.25-inch DOS 3.3 disk.