How to multiplex 4x7segments with switches by using timer interrupt.

I am using AT89c2051 to multiplex 4x7 segments by configuring P3 as buffer for segments and P1.0~P1.3 as control bits for segments,two switches also connected at P3.0 and P3.1, I used the timer interrupt for multiplexing but i failed to use switches because thats are connected at same port which is being used for buffer for segments.Can anyone tell me how to use switches when using timer interrupt.

More questions in this forum