Motorola MVME166, Installation Manual

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Autoboot
MVME166IG/D2 3-9
3
Autoboot
Autoboot is a software routine that is contained in the 166Bug Flash /ROM
firmware to provide an independent mechanism for booting an operating
system. This autoboot routine automatically scans for controllers and devices
in a specified sequence until a valid bootable device containing a boot media
is found or the list is exhausted. If a valid bootable device is found, a boot from
that device is started. The controller scanning sequence goes from the lowest
controller Logical Unit Number (LUN) detected to the highest LUN detected.
Controllers, devices, and their LUNs are listed in Appendix B.
At power-up, Autoboot is enabled, and providing the drive and controller
numbers encountered are valid, the following message is displayed upon the
system console:
"Autoboot in progress... To abort hit <BREAK>"
Following this message there is a delay to allow you an opportunity to abort
the Autoboot process if you wish. Then the actual I/O is begun: the program
pointed to within the volume ID of the media specified is loaded into RAM
and control passed to it. If, however, during this time you want to gain control
without Autoboot, you can press the <BREAK> key or the software ABORT or
RESET switches.
Autoboot is controlled by parameters contained in the ENV command. These
parameters allow the selection of specific boot devices and files, and allow
programming of the Boot delay. Refer to the ENV command in Appendix A
for more details.
C
aution
Although streaming tape can be used to autoboot, the same
power supply must be connected to the streaming tape
drive, controller, and the MVME166. At power-up, the tape
controller will position the streaming tape to load point
where the volume ID can correctly be read and used.
If, however, the MVME166 loses power but the controller
does not, and the tape happens to be at load point, the
sequences of commands required (attach and rewind)
cannot be given to the controller and autoboot will not be
successful.