Romboot - Motorola MVME2300SC Series Installation And Use Manual

Startup and Operation
2
!
Caution

ROMboot

2-8
Although you can use streaming tape to autoboot, the same power supply
must be connected to the tape drive, the controller, and the
MVME2300SC. 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 MVME2300SC 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.
The ROMboot function is configured/enabled via the ENV command
(refer to Chapter 3) and is executed at power-up (optionally also at reset).
You can also execute the ROMboot function via the RB command,
assuming there is valid code in the memory devices (or optionally
elsewhere on the board or VMEbus) to support it. If ROMboot code is
installed, a user-written routine is given control (if the routine meets the
format requirements).
One use of ROMboot might be resetting the SYSFAIL∗ line on an
unintelligent controller module. The NORB command disables the
function.
For a user's ROMboot module to gain control through the ROMboot
linkage, four conditions must exist:
Power has just been applied (but the ENV command can change this
to also respond to any reset).
Your routine is located within the MVME2300SC Flash memory
map (but the ENV command can change this to any other portion of
the onboard memory, or even offboard VMEbus memory).
The ASCII string "BOOT" is found in the specified memory range.
Your routine passes a checksum test, which ensures that this routine
was really intended to receive control at powerup.
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