Mohd:

Yes, what you are doing is supported in Pinnacle. Be sure you are setting and clearing P3.3 in the area of the window that says "Input." If you are changing P3.3 in the area of the window that says "Output Latch" the input will not be triggered.

I adapted your code to the following:

ORG 0000H
LJMP MAIN

ORG 0013H
PUSH ACC
PUSH PSW
NOP
POP PSW
POP ACC
RETI

MAIN:
SETB P3.3
SETB EX1
SETB IT1
SETB EA
SJMP $

I put a breakpoint on the NOP instruction. Each time P3.3 (in the input area) goes from 1-0, an interrupt is triggered.

Craig Steiner