HTB-100-HM170 Medical Box PC
Page 113
NOTE:
The following discussion applies to DOS environment. IEI support is
contacted or the IEI website visited for specific drivers for more
sophisticated operating systems, e.g., Windows and Linux.
The Watchdog Timer is provided to ensure that standalone systems can always recover
from catastrophic conditions that cause the CPU to crash. This condition may have
occurred by external EMI or a software bug. When the CPU stops working correctly,
Watchdog Timer either performs a hardware reset (cold boot) or a Non-Maskable Interrupt
(NMI) to bring the system back to a known state.
A BIOS function call (INT 15H) is used to control the Watchdog Timer:
INT 15H:
AH – 6FH Sub-function:
AL – 2:
Sets the Watchdog Timer’s period.
BL:
Time-out value (Its unit-second is dependent on the item “Watchdog
Timer unit select” in CMOS setup).
Table D-1: AH-6FH Sub-function
Call sub-function 2 to set the time-out period of Watchdog Timer first. If the time-out value
is not zero, the Watchdog Timer starts counting down. While the timer value reaches zero,
the system resets. To ensure that this reset condition does not occur, calling sub-function
2 must periodically refresh the Watchdog Timer. However, the Watchdog timer is disabled
if the time-out value is set to zero.
A tolerance of at least 10% must be maintained to avoid unknown routines within the
operating system (DOS), such as disk I/O that can be very time-consuming.
Summary of Contents for HTB-100-HM170
Page 14: ......
Page 15: ...HTB 100 HM170 Medical Box PC Page 1 Chapter 1 1 Introduction...
Page 22: ...HTB 100 HM170 Medical Box PC Page 8 Chapter 2 2 Unpacking...
Page 26: ...HTB 100 HM170 Medical Box PC Page 12 Chapter 3 3 Installation...
Page 49: ...HTB 100 HM170 Medical Box PC Page 35 Chapter 4 4 BIOS...
Page 91: ...HTB 100 HM170 Medical Box PC Page 77 Chapter 5 5 Troubleshooting and Maintenance...
Page 97: ...HTB 100 HM170 Medical Box PC Page 83 Chapter 6 6 Interface Connectors...
Page 112: ...HTB 100 HM170 Medical Box PC Page 98 Appendix A A Regulatory Compliance...
Page 117: ...HTB 100 HM170 Medical Box PC Page 103 B Safety Precautions Appendix B...
Page 123: ...HTB 100 HM170 Medical Box PC Page 109 Appendix C C BIOS Menu Options...
Page 126: ...HTB 100 HM170 Medical Box PC Page 112 Appendix D D Watchdog Timer...
Page 129: ...HTB 100 HM170 Medical Box PC Page 115 Appendix E E Hazardous Materials Disclosure...
