Thanks to all of you
I am sorry that I didn't explained my question. My problem is not bidirectional port. I am using it in both directions by implementing all the handshake signals through software and using bit 5 to change direction. It is working fine. But all the handshake signals are generated automaticaly by hardware in EPP mode if we simply write/read BaseAddress+3 of parallel port for address and BaseAddress+4 for data.
Another problem I encountered while shifting serial data through parallel port pins into 74HC4094 shift register. It was working fine on old computers but not on new ones. I just inserted a schmitt trigger and now it is working. I also read about 74HCT1284 and some other ICs for interfacing. That's why I was thinking that it may be a bus termination problem and some noise is disturbing the signal.
thanks
NS