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Startup and Operation
2
Autoboot
Autoboot is a software routine included in the 167Bug EPROM to provide
an independent mechanism for booting operating systems. The 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 D.
At power-up, Autoboot is enabled and (provided that the drive and
controller numbers encountered are valid) the following message is
displayed upon the system console:
Autoboot in progress... To abort hit <BREAK>
A delay follows this message so that you can abort the Autoboot process if
you wish. Then the actual I/O begins: the program designated within the
volume ID of the media specified is loaded into RAM and control passes
to it. If you want to gain control without Autoboot during this time,
however, you can press the <Break> key or use the ABORT or RESET
switches on the front panel.
The Autoboot process 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 description in Chapter 3 for more details.
!
Caution
Caution
Although you can use streaming tape to autoboot, the same power supply
must be connected to the tape drive, the controller, and the MVME167P.
At power-up, the tape controller will position the streaming tape to the load
point where the volume ID can correctly be read and used.
However, if the MVME167P loses power but the controller does not, and
the tape happens to be at load point, the necessary command sequences
(Attach and Rewind) cannot be given to the controller and the autoboot
will not succeed.
