The differences between 2.0.1 and 2.0.3 were very minor minor bug fixes
that never did crop up in normal use but the engineers knew they were there
and fixed them anyway.
For the System 7 driver, it was modified to include a reentrant driver for
support of virtual memory. The driver is written to the disk very early in
the boot process to a portion of the drive to which we, as users, do not
have access.