Hi Erik, Thanks for your reply,
No input should be a uC pin.

I am taking care of the above by
1. For triac driving
micro->74HC541--board2-->MOC3081->triac+snubber-> Inductive Load.
2. For stepper motor drives.
micro->74HC541--Board 2-->4N35 opto->stepper drive.
3. For inputs from proximity sensor.
proximity sensor->4N35 opto--Board 1-->74HC541->micro.
4. For LCD driving.
micro->74HC541--8 inch cable-->20x2 LCD.
5. For input from a PC style PS/2 Keyboard.
PS/2 Keyboard -> micro.

The question coming in mind is should I use some sort of filter or buffer in between keyboard and micro in order to satisfy No input should be a uC pin.

Thanks & Regards,
Prahlad Purohit