@Robin2 sure I want to control it without any library 
But my question remains: what does the number inside delayMicroseconds(x) means? In this thread some of you said you are using X = 500, others sayins are using X = 800.
Let's do the math: if X = 500us, so the period of each step will be 1ms, so if the motor is a 200/step it will run at 300 RPM which is too HIGH cause many of you said I should be below 300 RPM
So, if X = 500us, RPM = 300. Is this correct?
What value of X do you recommend in which I will have the maximum torque? High values of X (and low RPM) causes better torque?