i don;t know what has got into this forum but iam Lance Austin and there is no relationship between me and waqar. My project is to control A Security system as mentioned before including PIRs etc... using controller, DTMF decoder.

Ya its right that PBX and my project has some similarities but both entirly different projects.

why iam asking this state machine concept is because to understand how to do the following and if you check my previous post i always try to ask specfic questions not like waqar who puts the entire project in front of all of you.

p1 is connected to 7 senors
software monitor these pins using the Michael's method of previous and new state.

Now iam looking forward to understand suppose if P1.1 is set now the monitoring should continue but some how P1.1 is removed from the monitoring list untill the sensor is off again.

Means software using Listing oepration:-

when a low comes on any bit of port 1 the next time software should monitor the remaining bits or some how the bit which is active low is removed from monitoring list but as soon as that bit gets logic high the software again should start monitoring the entire bits including that one..

i have another interrupt question but i like to have the permission from all of you first.