I am working in an LCD keypad module for an industrial controller using AT89S52 processor. Developemnt platform is KEIL IDE. I have done the coding and right now i am doing testing of coded modules. For this i am using in built simulator of keil. here i am experiencing some problems. I real case all the pins are pulled up so when ever key stroke occcur the corresponding pin will be GNDed. once the key is released i goes back to high again. How this situation cud be simulated in keil. I wrote a debugging function to give external I/P to port pin to signify key strokes. that func is activated on pressing a button. But i have to presss another button to bring port back to norm state. by this time the program would have taken many keystrokes. So i want somthg which will bring port pins back to norm state once keypins are read by simulator. this kinda situation wont arise if you use an in circuit debuger.