HP 330 Service Information Manual page 158

Booting Operating Systems
Boot System Selection
The Boot ROM provides two nlOdes of operation, attended and unattended. These two modes
allow a user to either select from several operating systems on mass storage devices or to
automatically boot an operating system (OS) with no user intervention.
Unattended Operation
In an Unattended situation, the first operating system found will be loaded and given control.
To find an OS, the Boot ROM will search a boot list of prioritized devices. The first OS found
on one of these devices will be booted. If none is found, the boot list will be searched again until
a one is found. This allows discs not present at power-up to be found after their initialization
is complete.
Once a device has been successfully accessed, it will never be accessed again until re-power-up
or a reset. This minimizes wear on nlass storage devices and limits the confusion of operating
systems disappearing and re-appearing on shared resource management systems.
To force the boot of a particular system when the nlachine is unattended, the user has the
following options:
• Make sure that the OS to be booted is the first to be found according to the boot list
search. This is quite easy to do simply by changing device addresses, select codes, or OS
names, or by moving OSses. The prioritized boot list is discussed in detail latter in this
section .
• On an SRM with multiple OSses, make the first OS to be found one that looks at the
host's SRM node address and uses the node address to decide what secondary OS to boot.
(The Boot ROM can then be called to boot a particular OS.)
Attended Operation
To force the boot of an OS not chosen by the boot list, the user must enter Attended Operation
Mode. This mode is entered by pressing the space bar,
I
Return
I,
or any letter or number during
power-up after the input portion of the human interface (i.e., the keyboard or terminal) has
been initialized but before a default OS is booted. A good way to do this is to hold down the
space bar until the OS selection menu is seen. This will cause a boot selection menu to be
displayed. A user can be sure that the input human interface has been initialized when one of
the following (depending on the human interface provided) is displayed in the self-test list:
Keyboard Message Keyboard Electronics Select Code
Keyboard
System interface board HP-HIL section
Console Keyboard at
Where XX is the lowest select code of keyboard electronics in an I/O slot.
xx
HP 986XX at X
Where the Xs are the type and select code of the remote human interface.
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Boot ROM Functions