A-2
AlphaServer DS20 Service Manual
A.1
Halt Button Functions
The Halt button causes the system to perform in various ways depending upon
the system state at the time the button is pressed.
When the Halt button is pressed, results differ depending upon the state of the
machine. Table A-1 describes the full function of the Halt button.
Table A-1 Results of Pressing the Halt Button
Machine State
Result
OpenVMS running/hung
SRM console runs
Compaq Tru64 UNIX running/hung
SRM console runs
Windows NT running/hung
Nothing
AlphaBIOS running/hung
Nothing
SRM console running
Sets halt assertion flag: the SRM console
continues to run
SROM (1
st
2 secs. of pwr-up)
Nothing
XSROM power-up
Sets halt assertion flag, auto boot ignored
SRM console power-up
Sets halt assertion flag, auto boot ignored
A simple halt causes suspension of a system that is hung or running Compaq Tru64
UNIX or OpenVMS and starts the SRM console.
The halt assertion flag is set in the TOY NVRAM; it is read and cleared by the console
only during power-up or reset. When the SRM console finds the halt assertion flag
set, the conditions of the environment variables auto_action = boot/restart and
os_type = NT are ignored; the SRM console runs and prints the following message:
Halt assertion detected
NVRAM power-up script not executed
AUTO_ACTION=BOOT/RESTART and OS_TYPE=NT ignored, if applicable
P00>>>
