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You determine when the password is required within the BIOS Features
Setup Menu and its Security option (see Section 3). If the Security
option is set to password will be required both at boot and at entry to
Setup. If set to “Setup”, prompting only occurs when trying to enter
Setup.
4.16 Exit Selecting
Save & Exit Setup
Pressing <Enter> on this item asks for confirmation:
Save to CMOS and EXIT (Y/N)?
Y
Pressing “Y” stores the selections made in the menus in
CMOS – a special section of memory that stays on after you
turn your system off. The next time you boot your computer, the
BIOS configures your system according to the Setup selections
stored in CMOS. After saving the values the system is restarted
again.
Exit Without Saving
Pressing <Enter> on this item asks for confirmation:
Quit without saving (Y/N)?
Y
This allows you to exit Setup without storing in CMOS any
change. The previous selections remain in effect. This exits the
Setup utility and restarts your computer.
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5
Appendix A. Watch-Dog Timer
The WatchDog Timer is a device to ensure that standalone systems can
always recover from abnormal conditions that cause the system to
crash. These conditions may result from an external EMI or a software
bug. When the system stops working, hardware on the board will
perform hardware reset (cold boot) to bring the system back to a known
state.
Three I/O ports control the operation of WatchDog Timer.
443 (hex)
Write
Set WatchDog Time period
443 (hex)
Read
Enable the WatchDog Timer.
043/843 (hex)
Read
Disable the WatchDog Timer.
Prior to enable the WatchDog Timer, user has to set the time-out period.
The resolution of the timer is 1 second and the range of the timer is from
1 sec to 255 sec. You need to send the time-out value to the I/O port –
443H, and then enable it by reading data from the same I/O port – 443H.
This will activate the timer that will eventually time out and reset the CPU
board. To ensure that this reset condition won’t occur, the WatchDog
Timer must be periodically refreshed by reading the same I/O port 443H.
This must be done within the time-out period that is set by the software,
please refer to the example program. Finally, we have to disable the
WatchDog timer by reading the I/O port -- 843H or 043H. Otherwise the
system could reset unconditionally.
A tolerance of at least 5% must be maintained to avoid unknown
routines in the operating system (DOS), such as disk I/O that can be
very time-consuming. Therefore if the time-out period has been set to 10
seconds, the I/O port 443H must be read within 7 seconds
.
