Technical data

2-8 Computer Group Literature Center Web Site
Startup and Operation
2
The board’s self-tests and operating systems require that the real-
time clock be running.
Autoboot
Autoboot is a software routine that is contained in the 172Bug
Flash/PROM 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 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 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.
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
Although you can use streaming tape to autoboot, the same
power supply must be connected to the tape drive, the
controller, and the MVME172LX. 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.