A standard PC parallel port is uni-directional, and ALL PC parallel ports are compatible with this standard. However, there are a number of later parallel port standards, such as EPP or ECP - these are bi-directional, but require different programming than a standard port.
A standard port has five handshake lines which are inputs, and for maximum compatibility you should probably only use that method (which will work on any PC parallel port).
Anyway, why do you want to use the parallel port for transferring data, and not the serial port? - it's a lot easy to use the serial port, and it's generally much faster than required.