Hi: I use Keil Simulator to debug my program,and I select Atmel's chip which named AT89S51, it has a watchdog timer in it. The watchdog timer will rise a reset after software not "feed dog" more than 16383 machine cycle. But I find the watchdog timer will rise a reset after 8192 machine cycle when I use Keil's Soft Simulator. Is this a Keil Simulator's bug? I use 12Mhz setting in the target table's Xtal setting. Can enyone help me?