The Amiga operating system contains support for matching up disk-based
drivers with AUTOCONFIG boards.  Though such drivers are commonly Exec
devices, this is not required.  The driver may, for instance, be an Exec
library or task.  Since 1.3, the system software also supports the
initialization of onboard ROM driver software.

 disk based drivers           rom based and autoboot drivers 
 expansion drivers and dos    rigiddiskblock and alternate filesystems