IEI Technology uIBX-200-VX800 User Manual

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uIBX-200-VX800 Embedded SystemPage 99NOTE:The following discussion applies to DOS. Contact IEI support or visit the IEIwebsite for drivers for other operating systems.The Watchdog Timer is a hardware-based timer that attempts to restart the system when itstops working. The system may stop working because of external EMI or software bugs.The Watchdog Timer ensures that standalone systems like ATMs will automaticallyattempt to restart in the case of system problems. I/O address A61h start counter output A61h twice stop counter output A61h = 0A tolerance of at least 10% must be maintained to avoid unknown routines within theoperating system (DOS), such as disk I/O that can be very time-consuming.NOTE:The Watchdog Timer is activated through software. The softwareapplication that activates the Watchdog Timer must also deactivate itwhen closed. If the Watchdog Timer is not deactivated, the system willautomatically restart after the Timer has finished its countdown.EXAMPLE PROGRAM:mov dx, 0A61hmov al 03hout dx, alout dx, al