is the firmware that implements all processor-dependent functionality,
including initialization and self-test of the processor.
Upon completion, it loads and transfers control
to the initial system loader
Firmware behavior varies somewhat, depending on the hardware
as described below.
from an external medium,
must know the particular device on which
Typically the device is identified by the Primary Boot Path
that is maintained by
in Stable Storage.
specification is an
subsystem mnemonic that varies according to hardware model.
When the processor is reset after initialization and self-test complete,
reads the Console Path from Stable Storage,
and attempts to initialize the console device.
If the initialization fails,
attempts to find and initialize a console device.
Algorithms used to find a console device are model-dependent.
then announces the Primary Boot, Alternate Boot, and Console Paths.
provides a 10-second delay,
during which time the operator can override the
sequence by typing any character on the console.
If the operator does not interrupt this process,
initializes and reads
from the Primary Boot Path.
On models that support autosearch, if this path is not valid and
to find a bootable medium.
If allowed to complete, a list of potentially bootable devices
is displayed, labeled with abbreviated path identifiers
(P0, P1, etc).
A simple menu is then displayed where the user can:
Boot a specific device, using the abbreviated path
identifier, or the full mnemonic.
Start a device search where the contents are searched for
images (note the first search only identified devices
and did not check the contents).
Enter the boot administration level.
Exit the menu and return to autobooting
sequence is unsuccessful, overridden by the operator,
or not enabled in the first place,
interactively prompts the operator for the Boot Path to use.
Any required path components that are not supplied default to zero.
The Primary Boot, Alternate Boot, and Console Paths as well as
enable can be modified via