Appendix A Programming the Watchdog Timer 71
After data entry, your program must refresh the watchdog timer by
rewriting the I/O port 443 (hex) while simultaneously setting it. When
you want to disable the watchdog timer, your program should read I/O
port 443 (hex).
The following example shows how you might program the watchdog
timer in BASIC:
10 REM Watchdog timer example program
20 OUT &H443, data REM Start and restart the watchdog
30 GOSUB 1000 REM Your application task #1,
40 OUT &H443, data REM Reset the timer
50 GOSUB 2000 REM Your application task #2,
60 OUT &H443, data REM Reset the timer
70 X=INP (&H443) REM, Disable the watchdog timer
80 END
1000 REM Subroutine #1, your application task
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1070 RETURN
2000 REM Subroutine #2, your application task
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2090 RETURN
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