how to make 4 wires system of Unipolar Motor control into 2 wires

Using Arduino Motors, Mechanics, Power and CNC
1

is there any way to modify this schematic in to 2 wires system?eg. dir,steps http://upload.wikimedia.org/wikipedia/commons/5/56/Unipolar_Stepper_Motor_Driver.png

2

You can try an Allegro UCN5804B. It's a pretty old chip; unipolar drivers just aren't very popular.

3

It can be done using a couple of logic chips.
http://neil.fraser.name/hardware/stepper/ttl.html

4