Hello, i am using the MSC1210 for my project. My project consists of 2 parts: the Master Card and the Slave Card. Now when an alram condition occurs, i want the slave card to interrupt the master card. For this i am using the INT0 pins on the MSC.i.e. the INT0 pin on the Slave card is initialy hel high & when the alarm condition occurs the slave card pulls this low so as to interrupt the master which also uses the INT0 line. my problem is as long as i dont connect the 2 pins on the 2 cards, i have both cards running fine. when i connect these 2 pins, the master card starts malfunctioning & then even if i reset the ckts. after disconnecting the pins, the master card stil doesnt start working properly. i have to reprogram the master ic for proper functioning. Also in the statndard Reg1210.h file provided by the Keil compiler, INT0 pins are configured as inputs. Compiler doesnt allow modifying in this file. Even if i try to reconfigure these pins as output on the slave side & std. 8051 on the master side, the problem persists. Kindly suggest a way out. Thanx...