Technical data

Restarting the System
http://www.mcg.mot.com/literature 2-11
2
Restarting the System
You can initialize the system to a known state in three different ways:
Reset, Abort, and Break. Each method has characteristics which make it
more suitable than the others in certain situations.
A special debugger function is accessible during resets. This feature
instructs the debugger to use the default setup/operation parameters in
ROM instead of your own setup/operation parameters in NVRAM. To
activate this function, you press the
RESET and ABORT switches at the
same time. This feature can be helpful in the event that your
setup/operation parameters are corrupted or do not meet a sanity check.
Refer to the ENV command description in Chapter 3 for the ROM
defaults.
Reset
Powering up the MVME172LX initiates a system reset. Resets can also be
asserted through the
RESET switch on the MVME172LX front panel, or by
software.
For details on resetting the MVME172LX board through software, refer to
the MVME172 Embedded Controller Programmer’s Reference Guide.
Both “cold” and “warm” reset modes are available. By default, 172Bug is
in “cold” mode. During cold resets, a total system initialization takes place,
as if the MVME172LX had just been powered up. All static variables
(including disk device and controller parameters) are restored to their
default states. The breakpoint table and offset registers are cleared. The
target registers are invalidated. Input and output character queues are
cleared. Onboard devices (timer, serial ports, etc.) are reset, and the two
serial ports are reconfigured to their default state.
During warm resets, the 172Bug variables and tables are preserved, as well
as the target state registers and breakpoints.
Note that when the MVME172LX comes up in a cold reset, 172Bug runs
in Board mode. Using the Environment (ENV) or MENU commands can
make 172Bug run in System mode. Refer to Chapter 3 for specifics.