banh,
because you are vietnamese, you can come to
www.diendandientu.com to see my translated tutorial of Stepping control of Douglas W. Jones. He's my "online" teacher. He's taught meeh via email for 2 years.
If you wanna see the original document, search for Douglas W. Jones
Its a wonderful Stepping control tutorial.
The torque in these 2mode of full step and half step is different.
At full step, if you enable 2 winding at a time, you get 1.4 times stronger torque than normal. But at half step, the torque will change each half step, 1, 1.4, 1, 1.4 ...etc. Half step is the combination of 2 full step mode.
Half step creat higher resolution.
revolution = cycle, it depends on the number of pulse, not on the half step or full step modes.
With full step, you need N pulses to turn the motor a revolution, in half step, you need 2N pulses. Pulses here means a control vector.