i was trying to remodify my application with external watchdog and reset ,and then the guy who sales Sipex chips mention that the cpu is CMOS type , should need more than 10 Sec to wait for the discharge befor replugin the power.originaly the dc power came with a 20 pins fletcable , and i had 470uf apacitor on boards So I add 1k OHM for discharge the power on board . and i'd test my application it works ok maybe it's not a very good solution ,however it's the best way so fare , I'll keep check anyway
i'd change the cpu to AT89c8252 and it works better then Philips P89c61x2