871225.33.PE1CHL.900519:

"watchdog" command now also installed in PC version.  It can only drive an
external watchdog timer.  The syntax of the watchdog command is:
	watchdog [<port> <value>]
When specified, the <port> and <value> select the output port to be used for
the watchdog.  The value is OR-ed to the value read (input) from the port, and
this value is output to the port.  Some time later the value is complemented and
AND-ed to the port value.  The result should be that one or more output bits
toggle at each pass through the main loop.
The watchdog triggering can be stopped by specification of a zero <value>.